One of Brian Miller's Garden Tractor Pulling Tips and Tricks.

Vital Information about Engine Rebuilding,

Buildups and Modifications

This page was last updated 11/4/08 . What Type of Motor Oil Should Be Used? Brian Miller's Engine Rebuilding and Buildup Service (updated 9/28/07) Click HERE for Kohler K-Series & Magnum - Single Cylinder Engine Specifications, Tolerances |

Torque Values and Sequences for Fasteners. Install an Auxiliary Crankcase Breather for Better Engine Venting Above 4,000 rpms. To search for a word or phrase in this Web page, with Microsoft Internet Explorer 6.x, press CTRL+F to open the Find

dialog box.

The Differences Between the Old Kohler K-series and the Newer Kohler Magnum Engines -

The Magnum engines replaced the older K-series in later years. The Magnum engines are basically the same engine as the K-series. The main differences are, besides the sheet metal that covers the block, the Magnum has solid state electronic ignition, a fixed main jet (Walbro) carburetor and the starter fastens to the bearing plate instead of the engine block. And there are no provisions for using ignition points. Most of the external and all the internal parts are interchangeable, and most aftermarket (high-performance) parts are interchangeable with either engine. If you need an engine, look in my advertisement web site or you can place a want ad in the same site. Or, call or visit your local small engine, lawnmower or tractor sales/repair shops. Sometimes they have old Cub Cadets sitting around that people sell or trade in for a new garden tractor. To identify certain models of IH Cub Cadets, check out Jonathan Luckeys web site at http://www.geocities.com/jluckeycub.

And if you're looking for some yellow paint to paint your Cub Cadet with, try your local farm and home supply store. They usually have International Harvester Yellow. It closely matches the color of Cub Cadet yellow.

Why Aluminum Block Engines (except V-Twins) Don't Work Well for Pulling Competition -

An aluminum engine block will "bend and twist" or flex a few thousands of an inch when hot and under pulling stress. Therefore, they'll lose valuable compression because the valves become unseated and the piston rings lose partial contact against the cylinder wall. Not to mention the main bearings are also put into a bind under the stress of pulling.

Cast iron engine blocks on the other hand hold their shape a lot better when hot and under stress. Aluminum engines work best for conditions that doesn't place them in a lot of stress. Such as ATVs, racing go-karts, racing lawn mowers, etc. Because there's fresh air moving over the engine, keeping the metal cool, and the block isn't being strained by the vehicle pulling a heavy load. That's why cast iron Kohler engines work best

for competitive pulling. Because cast iron is able to "hold its shape," handle high operating temperatures, severe stress, high compression and very high rpms (above 4,000 rpm). This is why riding mowers, lawn tractors, lawn and garden tractors all have aluminum block engines. And most garden tractors have a cast iron engine block.

In addition, on the cast iron block single cylinder Briggs and Stratton and Tecumseh engines, the valve stems are parallel to the cylinder. This means that the valve heads set further away from the piston. And in the cast iron block single cylinder Kohler engines, the valve heads are set closer to the piston (valve stems are angled). Therefore, the other engines can't build up as much compression as the Kohler engines can. Plus, they can't flow as much air in and out of the combustion chamber at high rpms, like the Kohler engines can.

To gain more power and torque from virtually any flathead two or twin cylinder engine, perform a professional valve job and the valve clearances will need to be increased. Resurface the cylinder heads on a flat sanding disc to insure proper head gasket sealing. Nothing else may be needed to be done to the engine, except for perhaps a professional tune up. I found that many twin cylinder engines have inadequate valve clearances and this robs the engine of proper operation and valuable power. Perform a professional valve job, and set the clearances (between the valve stems and lifters) at .010" for the intake and .014" for the exhaust. After increasing the valve clearances, the engine will start quicker, idle better and produce more power at low and high rpms. Top of page

To install a twin cylinder engine into a Cub Cadet, on the narrow and wide frame Cubs, the frame rails will need to be cut down for installation of an opposed twin cylinder engine. But the spread frame Cubs are made for the opposed twin cylinder engine. And a V-twin engine will fit in virtually into any Cub Cadet with few modifications. The frame rails shouldn't have to be altered either. Go here for an example of a V-twin that was installed in a wide frame Cub Cadet: http://www.smallenginewarehouse.com/RepowerItems.asp?Brand=Cub%20Cadet&Model=1000.

When rebuilding an aluminum block engine, remember - as an aluminum block and cylinder head get hot for the first time, they "warp" or bend and twist a few thousands of an inch due to normal engine heat. This is called block (and related parts) warping. In other words, the metal "takes shape." It's normal for new engine parts and unavoidable. So be sure to have the cylinder head and other parts resurfaced on a flat sanding disc to insure 100% gasket sealing, and bore the cylinder to insure a 100% piston ring seal. After the parts get hot again, they will not bend and twist again. This is a one time deal.

How To Determine If An Engine Needs To Be Rebuilt -

Before the engine is removed from the tractor and disassembled, first, remove the cylinder head and observe the top of the piston. If it's covered with carbon, then the piston rings are in good condition. But if some of the carbon is washed away and there's oil present, this means that the rings are worn and the piston and rings need replacing, or maybe the cylinder needs to be rebored for installation of an oversized piston and rings assembly.

Now move to the valves. To test for leaking valves, with the cylinder head removed and the piston at TDC on the compression stroke (both valves fully closed), spray some WD-40 or an equivalent liquid around each valve and then use compressed air to blow through the exhaust and intake ports. Wrap a rag around the air nozzle and place it snug against the port so full air pressure will be against the valve. If bubbles form around the valves when applying the air pressure, this means that the valves are leaking and a professional valve job is required.

To remove the engine from a typical IH Cub Cadet, first disconnect the battery negative terminal and

disconnect all the wiring from the engine and fuel line if the gas tank is separate from the engine. Then remove the PTO clutch engaging linkage, remove the engine mounting bolts, then slide the engine forward so it'll clear the clutch disc or driveshaft, then lift the engine out of the tractor.

Now remove the oil pan and connecting rod cap. Observe the rod cap for scoring or burning. Replace or repair it if necessary. Also, the crankshaft journal may be worn and if it is, it will need to be reground to the next undersize. And have the crank journal mic'd (precision measured with a micrometer) to determine if it's excessively worn. If it is worn, it can be reground to .010" and a .010" undersize connecting rod can be used or you can have your old rod bored for installation of .010" bearing inserts. But if it needs to be reground to .020" or .030", the rod will need to be bored for installation of matching bearing inserts. The only OEM rods available without a bearing are STD and .010" undersize.

The diameter of the Kohler crankshaft rod journals are as follows: K90/K91 (4hp)

.9355" (minimum) .9360" (maximum.)7hp (K141/K161), 8hp (K181)

1.1855" (minimum) 1.1860" (maximum)

10hp-16hp flatheads and 18hp OHV engines

STD. = 1.499" (minimum) 1.500" (maximum)

.010" = 1.489" (minimum) 1.490" (maximum)

.020" = 1.479" (minimum) 1.480" (maximum)

.030" = 1.469" (minimum) 1.470" (maximum)

Click HERE for Complete Kohler Single Cylinder Engine Specifications and Tolerances.

If the cylinder wall is badly scored or tapered, have it bored to the next oversize. The only pistons available for a stock engine are STD, .010", .020" and .030". If the cylinder is worn beyond for installation for a .030" piston/rings assembly, it will need to be sleeved for installation of a STD size piston/rings assembly. But if building an engine for more power, don't have the cylinder bored to a maximum of .030" if it doesn't need it. Because a .030" overbore won't necessarily give an engine more power. Having a longer crankshaft stroke increases the power.

And if you're wondering, the old model K141 (6.6hp) engine has a bore diameter of 2-7/8". The model K161 (7hp), which replaced the K141, has a bore of 2-15/16". It uses the same piston/rings assembly as the model K181 (8hp) engine. Pistons/rings assemblies are no longer available in the 2-7/8" size. When rebuilding a K141, the cylinder must be bored for use with a 2-15/16" piston/rings assembly, which will then make it a model K161. The connecting rod and crankshaft are the same in the K141 and K161, but is different in the K181.

Most of the time, cleaning the burnt aluminum from a crankshaft journal won't work because the journal itself may be scored or worn. Therefore, it'll be better to have it reground to the next undersize and install a matching undersize connecting rod. Or if an undersize rod or bearing inserts isn't available, have it reground undersize (to wherever it "cleans up") and resize the connecting rod for proper fit.

With engines when there's no an undersize connecting rod or bearing inserts available, if the crank journal is worn beyond STD and needs to be reground, it can be reground to where it is perfectly round again, and then the connecting rod can be resized so it'll fit the smaller diameter undersize journal.

To fit the rod to a smaller crank journal...

1. First, the worn crank journal is reground until it's perfectly round again, despite if it's .006", .008" or whatever.

2. Then a few thousands of metal is removed from the mating end of the rod cap. 3. Fasten the cap to the rod. The big hole in the rod is now oblong or "egg shaped." 4. Resize the hole until it's .002" larger than the diameter of the crank journal. This reshapes the hole

into a perfect circle again, only smaller in diameter. This can only be performed on a rod with a good bearing surface. It cannot be done on a burnt or heavily scored connecting rod.

5. This works very well and it lasts as long as an ordinary STD rod and crank journal. Click here if you're interested in having this service performed.

Don't Be A Slob When Rebuilding An Engine!

Always be professional whenever you rebuild an engine! Before assembling a fresh engine, always take the time to provide a neat and absolutely clean work environment. Make sure that your repair table or bench is sturdy enough to support the weight of a fully assembled cast iron bock Kohler engine. And make sure that your tools, shop towels, engine parts and hands are clean, too. Don't allow any dust or dirt to enter the work area, including the engine block and it's internal parts. If necessary, place the engine parts on a large, clean cloth or cardboard to help keep them clean and organized until they're ready to be installed. The reason everything should be kept as clean as possible is because even the smallest bit of dirt inside an engine will "grind away" at the internal parts when the engine is in operation, causing unnecessary and expensive wear.

You can also use an automotive engine stand to rebuild a Kohler engine. Just use the two starter bolt holes on the side of the block to mount your engine to the stand. You can completely disassemble and reassemble the entire engine, except for the starter, and you can get at everything on the outside and inside of the engine with no problems.

To "basically" overhaul or rebuild an engine that burns a lot of oil, all that needs to be done on a Kohler engine is remove the oil pan and cylinder head, disconnect the connecting rod from the crankshaft and then drive the piston and rod out of the block with a long wooden stick and a medium size hammer. Inspect the entire piston and cylinder wall for wear. If no wear is evident, then install a new set of rings on the piston (thoroughly clean the parts first though) and reinstall the piston in the block as described. But to do a professional and complete rebuild, read the rest of the information in this web page and linked pages.

Information About Using Imported/Aftermarket Engine Parts -

Imported pistons, rings, rods and other parts hold up VERY WELL. I should know, I've used these parts in my own equipment and I've sold them to my customers. I've sold many of these parts for the past 26+ years and I haven't had one complaint from anyone. Besides, it's how well the engine block and crankshaft are machined (cylinder bored straight, crank journal reground to OEM specs, cleanliness of the parts and work area, etc.), that determines how well and how long internal engine parts hold up. Don't blame shoddy workmanship on shoddy parts.

Important Information About Kohler Crankshafts -

Crankshafts, rather being made of steel or cast iron, and despite how well-balanced the rotating parts are in a

pulling engine, suffer a lot of vibration at very high rpms in a single cylinder engine. Therefore, if possible, before purchasing a used crankshaft, it's best to look it over for hairline cracks with a strong magnifying glass or better yet, a microscope. And as I always say about buying anything off of eBay: BUYER BEWARE! So ask for a money-back guarantee, or you may have nothing but a piece of scrap metal on your hands.

Identifying Kohler Crankshafts -

To identify the 10, 12, 14 and 16hp Kohler crankshafts, the 10hp cranks have a shorter stroke than the other cranks. You can compare a 10hp crank to a 12, 14 or 16hp crank by placing them side by side, and with the counter weights down, looking at the bottom part of the rod journal, the journal on the 10hp will be closer to the main journals. (3/8" of difference in stroke.)

The 12hp crankshaft is different from the 14 and 16hp cranks because the counter weights are machined off for the lighter-weight 12hp piston assembly. NOTE: Some 10hp cranks also have the counter weights machined off like the 12hp does, but some don't.

And the 14hp and 16hp cranks are identical in weight and appearance. Some may have a few more holes drilled into the counter weights, but that's the only difference.

How to Remove Only the Crankshaft from a Kohler Engine -

1. Remove the flywheel and anything that's on the PTO end of the crankshaft. 2. Remove the cylinder head. 3. Remove the oil pan. 4. Remove the piston/connecting rod assembly from the engine block. 5. Remove the bearing plate. 6. Finally, being very gentle, bump the PTO end of the crankshaft with a large brass head hammer or a

large hammer and wooden block to remove it from the engine block. 7. And if an engine originally came with balance gears, there's no need to reinstall them. They serve

very little purpose and they may break, possibly destroying the engine block.

Here's Something Important To Keep In Mind About A Reground Crankshaft Journal -

Sometimes as the rod journal (crank pin) wears, it will develop a "flat spot" at a certain place when the piston is at the ATDC position on the compression stroke. The combustion process places the most pressure on the piston and connecting rod at this particular point, which squeezes the oil out between the rod bearing surface and crank journal, causing brief metal to metal contact. As this happens, this point wears more than the rest of the journal, causing the journal to become oval or "egg shaped." Sometimes the upper part of the connecting rod will wear as well, but in most cases, it's the part that moves the most that wears more, which is the crank journal.

When regrinding a journal, and if a standard size journal is not worn past .005" on the low side or the "flat spot," then the crank grinder person can regrind it "centered" to the next undersize, which is .010", or if he gives it an extra .001" of additional oil clearance, it'll have a .011" undersize journal and the crankshaft will retain it's original stroke. But if a standard size journal is worn .006" or more, then the crank grinder can "cheat" and regrind the journal to the next undersize by offsetting the journal .006" or more in the lathe and regrind it to .010". By doing this, and depending on the amount of wear the journal had and the location of the low side or "flat spot," the crankshaft will have a slightly longer or shorter stroke. Otherwise, if the severely worn journal were to be reground "centered," it would have to go to .020" undersize, and the stock stroke will be retained. The decrease or increase of the stroke on a crankshaft with a worn STD, .010" or .020" journal can vary from .001" to .005". and as much as .010" on a STD journal that's been reground to .020" undersize or even .015" on a STD journal that's been reground to .030" undersize! So when a pulling club's rules state that an engine must have the stock factory length stroke, and if a crankshaft was reground, it

may actually have a slightly longer or shorter stroke.

FYI - Oil clearance is the distance between the connecting rod bearing surface and crank journal. A thin coat of oil is supposed to keep all moving parts inside an engine from making contact with each other. If there's too little oil clearance between the rod and crank, especially in a high rpm engine, the rod will swell due to excessive heat, and then the rod will make contact with the crank and burn on the journal. If there's too much clearance, the rod will knock and possibly break at higher rpms, which could destroy the entire engine block.

When having a crank journal reground for an undersize bearing, it'll be a good idea to indicate to the crank grinder person that you want it ground for high-performance use by writing (with a bright-colored paint marker) the word RACE on one of the counterweights. The grinder person will then give the journal an additional .001" of oil clearance to prevent overheating both the bearing and journal. By the way - the extra .001" of clearance will not cause the rod to make a knocking sound.

More Information About the Crankshaft Journal -

The heat-treating or hardening process that Kohler uses on the rod journal area obviously goes deep into the crank. Because it's been proven that when the journal is ground for an undersize bearing, a .010", .020" or even a .030" undersize bearing can be used with no problem. Myself and many other pullers use undersize bearings in our pulling tractors, and we have no problems with the crank journal wearing. Heck, I've been using a .020" undersize bearing with the same crankshaft in my 30 c.i. tractor for 5 years and in about 75 pulls, and the crank journal hasn't worn at all. Most crank journals wear because of dirty motor oil or the wrong viscosity of oil is used. Not because of "soft metal" in the journal. Actually, the bearing material is not supposed to make contact with the crank journal. They're supposed to be kept separate by clean motor oil. And as far as cast iron Kohler crankshafts breaking is concerned, an undersize journal shouldn't make a cast crank break. I've always seen them break next to the journal, not in the journal area. As with anything, crankshafts break because something makes them break. Either out-of-balance parts, dirty flywheel taper/crankshaft taper or a manufacturing defect makes a crankshaft break.

By the way, a crank journal that's been turned .030" undersize will help to produce slightly more rpms and horsepower because there's less bearing surface to cause friction. Some NASCAR engineers do this to their racing engines. It works.

If you have a crankshaft that's made for a special purpose, and it has a worn .030" journal, and that particular crankshaft is no longer available, well, the journal can be welded up and reground back to STD. Here's one place who can do this for you: Big 2 Engine Rebuilders, Inc., 3214 25th Ave., Gulfport, MS 39501-5909 Phone: 228-863-5425 FAX: 228-868-8728. Ask for Pete Bloss.

How to Fix a Broken Off Crankshaft Stud (this happens a lot, by the way):

1. The easiest and quickest way to fix a broken off crankshaft stud is with the crankshaft in the engine is to place the engine on a drill press table with the crank end facing upward.

2. To install a 3/8-24 NF bolt, drill an 11/32" hole in the crank end at dead center, 1-1/2" deep. 3. Or to install a 5/8-18 NF bolt, as a pilot hole, drill an 11/32" hole in the crank end at dead center, 1-

1/2" deep. Then enlarge the hole with a 37/64" drill bit. 4. Place either a 3/8-24 NF or 5/8-18 NF tap (whichever you choose to use) in the drill's chuck to start

the threads straight into the crankshaft (to avoid starting the threads crooked). 5. Finally, install either a 3/8" or 5/8" diameter grade 5 bolt with a lockwasher and wide flat washer to

secure the flywheel to the crankshaft.

Another method to fix a broken off stud on a crankshaft with the crank out of the engine -

Basically, grind the remaining stud off the end of the crank, and then drill and cut threads for the 3/8" fine

thread bolt. And if you're going to use a hub and run like a Cub Cadet clutch or a pulley, the bolt must be centered exactly in the crankshaft. Otherwise, it'll wobble.

1. Chuck the PTO end of the crank in a metal lathe chuck, with the flywheel end supported by a steady rest.

2. To install a 3/8-24 NF bolt, drill an 11/32" hole in the crank end at dead center, 1-1/2" deep. 3. Or to install a 5/8-18 NF bolt, as a pilot hole, drill an 11/32" hole in the crank end at dead center, 1-

1/2" deep. Then enlarge the hole with a 37/64" drill bit. 4. Place either a 3/8-24 NF or 5/8-18 NF tap (whichever you choose to use) in the drill's chuck to start

the threads straight into the crankshaft (to avoid starting the threads crooked). 5. Finally, install either a 3/8" or 5/8" diameter grade 5 bolt with a lockwasher and wide flat washer to

secure the flywheel to the crankshaft.

Advertisement: (Updated 1/23/08)

If you need any of the services performed or items listed below, please contact me, Brian Miller, at A-1 Miller's Small Engine & Specialty Shop (1501 West Old Plank Rd., Columbia, Missouri. 65203 | Phone: 1-573-875-4033). Please call any day between 12 noon and 8:00 p.m. Central time, and please be patient because I stutter. Fax: 1-573-449-7347. You can also contact me through Yahoo! Messenger: E-mail: pullingtractor@aol.com.

Crankshaft Repairs -

Clean burnt aluminum and polish journal to shiny finish: $10.00 each journal. (The only problem with doing this is it may clean up nicely not be worn. If it is worn, it would need to be reground to the next undersize. If it's not worn, then a STD size connecting rod can be used. But if it is worn, an undersize rod and possibly one with a bearing insert is required. If it does need regrinding, then there's no charge for cleaning it.)

Regrind journal (crank pin): $50.00 per journal, plus return shipping. Note: Kohler crankshafts can be reground to .030" undersize and still be safe to use with matching undersized bearing inserts installed in the connecting rod. And all crankshafts, rather if they're automotive or small engine, are checked for straightness before grinding. If they're bent or twisted, sometimes they can be straightened. We also do offset crankshaft grinding to increase the length of the stroke at no extra charge.

With engines when there's no an undersize connecting rod or bearing inserts available, if the crank journal is worn beyond STD and needs to be reground, it can be reground to wherever it "cleans up" or is true again, and then the connecting rod can be resized so it'll fit the smaller undersize journal. To fit the rod to the smaller diameter crank journal, I remove metal from the mating end of the rod cap, then I fasten the cap to the rod. The big hole in the rod is now oblong or "egg shaped." Then I resize the hole until it's .002" larger than the diameter of the crank journal. This reshapes the hole into a perfect circle again, only smaller in diameter. This can only be performed on a rod with a good bearing surface. It cannot be done on a burnt or heavily scored connecting rod. This works very well and it lasts as long as an ordinary STD rod and crank journal.The cost for doing this is $75.00 labor, plus return shipping. If you're interested, I will need your crankshaft and connecting rod.

Repair broken off stud in crankshaft on flywheel end: $30.00 labor, plus return shipping. I drill and cut threads for a hardened 3/8" or 5/8" diameter bolt in the end of the crankshaft to secure the flywheel.

Drill hole and cut 7/16-20 NF threads in the PTO end of the crankshaft for a retaining bolt and flat washer. $20.00.

Used OEM Crankshafts -10hp, 12hp, 14hp and 16hp K-series and Magnum flathead single cylinder engine crankshafts. These cast iron cranks are a genuine Kohler part, they're used, but in good condition. These were in stock engines that never exceeded 3,600 rpm for a long period of time. They may have either a 1" or 1-1/8" diameter x 3-1/2" long keyed PTO shaft and may have a STD or freshly reground .010", .020" or .030" undersized journal. Although .030" is rare, it's still safe to use. [When available.]

10hp (K241/M10) $75.00 each, plus shipping. 12hp (K301/M12), 14hp (K321/M14), 16hp (K341/M16) and 18hp (K361) $100.00 each, plus

shipping. NOTE: I need to know the dimensions of the PTO shaft on your crankshaft so I can match it to

one that I may have in stock. I need to know the diameter and length from the gear teeth.

New main crankshaft bearings for 7hp and 8hp Kohler K-series and Magnum single cylinder cast iron flathead engines. These are specifically designed to provide maximum performance by means of precise ball implement selection. Heat treated. Good for high performance use. Made in China, but has the same quality as OEM Kohler bearings for long wear. Dimensions: 1.18" i.d. x 2.44" o.d. x .62" width. $10.00 each, plus shipping. Part # 150-960

New 8 ball main crankshaft bearings for 10hp, 12hp, 14hp, 16hp (flatheads) and 18hp (OHV) Kohler K-series and Magnum single cylinder cast iron engines. These are specifically designed to provide maximum performance through precise ball implement selection. At higher rpms, bigger balls run cooler which create less rolling resistance than bearings with smaller balls. Heat treated. Good for high performance use. Made in China, but has the same quality as OEM Kohler bearings for long wear. Replaces Kohler part # 235376. Dimensions: 1.57" i.d. x 3.54" o.d. x .90" width. $15.00 each, plus shipping. Part #150-973

NOTE: If you cleaned all the oil out of the crankshaft main [ball] bearings and then allowed them to dry, and then later you spun the bearings by hand, and if the bearings isn't worn much or at all, they might feel "rough" and make a rattling sound. This roughness or noise isn't necessarily because the bearing is worn out. The noise is mainly caused by the balls running dry on the races because there's no oil to separate them from the races. Try applying a small amount of motor oil to the balls/races and then spin them. They should be a lot quieter. The same thing will happen with new ball bearings.

Magnetic drain plug. Has 3/8" square head with 3/8" NPT threads. Universal fit. Helps trap metallic pieces inside crankcase to reduce engine wear. $3.50 each, plus shipping.

Oil Drain Valve. Has 3/8" NPT (right hand) threads. Universal fit. Easy to use. NOTE: Valve has left-hand threads. $7.00 each, plus shipping.

Flywheel retaining nut for crankshaft studs with 5/8-18 NF or 3/4-16 NF threads. Self-tightening jam nut. Guaranteed to stay tight! Torques at 65 ft. lbs. $1.00 each, plus shipping.

Flat washer for retaining flywheel and/or aluminum clutch hub adapter to flywheel. A must to secure flywheel and to prevent hub breakage! Available for a 5/8" or 3/4" stud. 1-1/4" o.d. x approximately 1/4" thick. $2.00 each,

Steel adapter step-washer for mounting the aluminum clutch hub with a 5/8" hole to the Kohler Magnum crankshaft with a 3/8" bolt. A must to prevent hub breakage! $8.00 each, plus

plus shipping.

shipping.NOTE: I can also custom machine other adapter washers to fit your particular application. All I need is the dimensions. $10.00 each, plus shipping.

How to Remove and Replace the Governor Gear Assembly in a Single Cylinder Kohler Engine -

1. Remove the internal parts of the engine (mainly the crankshaft and camshaft). 2. Remove the governor gear retaining screw (the Phillips head screw that's on the outside of the block). 3. The governor gear should now just slide off the stub shaft.

4. Be sure to remove and save the small thrush washer that's on the governor gear's stub shaft! (A lot of people are not aware of this hardened/heat-treated washer and it usually falls off and gets lost while washing inside the block.)

5. Install the new governor gear/flyweights assembly in reverse order of removal.

Plastic VS Cast Iron Governor Gear Assemblies - The most popular governor gear assembly nowadays for competitive stock garden tractor pulling are the ones that's made of cast iron. These are no longer made or available from Kohler or any other source. They were used in the 4hp, 7hp, early 8hp, 10hp and 12hp K-series Kohler engines 'til the late 1960s. (I don't know what year Kohler stopped making them.) It's impossible to tell if an engine has a metal governor gear by looking at it from the outside. The only way of knowing for sure is remove the oil pan and look at it.

There's really nothing special about the cast iron governor gear, except when the governor linkage is disconnected, they can withstand very high rpms and won't explode (break apart) like the plastic governor gears sometimes do. The reason the cast iron ones are so popular nowadays among stock pullers is because some pullers like to compete in two separate classes, one class that has an engine rpm limit of around 4,000 and another class with a higher rpm limit, or open rpms. The governor gear spins 1.25 times faster than the crankshaft. This means at 4,000 rpm, the governor gear spins at 5,000 rpm. And don't worry, the plastic governor gear assembly will hold up fine in an engine that will never operate above 4,000 rpms.

The cast iron governor gear will fit all Kohler K-series and Magnum 4hp-16hp flatheads, 18hp K361 OHV single cylinder cast iron block and the KT-series and Magnum flathead twin cylinder engines.

Plastic governor gear.

Good for up to 4,000 rpms.

Cast iron governor gear.

Good for open rpms.

Advertisement:

If you need a governor gear assembly, please contact me, Brian Miller, at A-1 Miller's Small Engine & Specialty Shop (1501 West Old Plank Rd., Columbia, Missouri. 65203 | Phone: 1-573-875-4033. Please call any day between 12 noon and 8:00 p.m. Central time, and please be patient because I stutter. Fax: 1-573-449-7347. You can also contact me through Yahoo! Messenger: E-mail:

pullingtractor@aol.com.

Used, but in good condition, governor gear assemblies for Kohler K-series and Magnum 10hp-16hp flatheads, 18hp K361 OHV single cylinder cast iron block engines, and KT-series flathead twin cylinder engines.

Plastic Material: $12.00 each, plus shipping. Good for up to 4,000 rpms. OEM Kohler part # A235743S. [When available.]

Cast Iron Material: $40.00 each, plus shipping. These won't break at high rpms. No longer available from Kohler. [When available.]

All K-series cast iron block single cylinder Kohler engines come with what is called a throttle stop. It's a piece of angled steel that's fastened under the lever where the governor spring and throttle cable is attached. If an engine doesn't have one, fabricate it out of 1/8" x 1/2" x 2" flat steel. Drill a 1/4" hole 1/2" from one end, and bend it in the middle 90 degrees, and then install it under the lever. To limit an engine's rpms of an engine, either adjust the throttle stop so the lever bumps against it, set the governor spring ends in different holes on the [long] governor lever, adjust the throttle cable housing or the linkage.

Advertisement: Top of page

If you need a Precision Handheld Tachometer, please contact me, Brian Miller, at A-1 Miller's Small Engine & Specialty Shop (1501 West Old Plank Rd., Columbia, Missouri. 65203 | Phone: 1-573-875-4033. Please call any day between 12 noon and 8:00 p.m. Central time, and please be patient because I stutter. Fax: 1-573-449-7347. You can also contact me through Yahoo! Messenger: E-mail: pullingtractor@aol.com.

To accurately determine the rpm of an air-cooled small gas engine is by using a quality wireless tachometer, such as the handheld tach by Dixson. This is a precision handheld solid state wireless tachometer with an analog reading. The antenna is held near the spark plug wire and it gives a correct reading rpm for all 2 and 4 cycle single and twin cylinder engines with magneto or battery ignition. Note: Divide the reading by half on an engines with camshaft operated ignition points. Reads 0 to 15,000 rpm in two scales. Works perfect when performing a tune-up, setting the rpms on all stock pulling tractors when rules require a limited rpm, and testing the rpm on high-performance engines. Uses one 9 volt battery, which is included with purchase. Manufactured by Dixson. $100.00 each, plus shipping to your zip code.

NEVER USE GASOLINE OR A HIGHLY FLAMMABLE LIQUID TO CLEAN YOUR PARTS! Gas cleans good, but it's extremely flammable, making it too dangerous to handle. The best (and safest) way to clean an engine block and its parts for rebuilding is to wash all parts with cleaning solvent (or mineral spirits, also known as paint thinner). Personally, I've always used paint thinner to clean my engine parts. I get it at Wal-Mart. That's the cheapest place I've found.

A product that works great for cleaning engine parts is Greased Lightning Multipurpose . But use caution when using this product! It will remove the paint. So it's best to use it on bare metal or parts that need repainting.

For stubborn or caked-on grime, use a heavy duty oven spray cleaner, such as EASY-OFF Heavy Duty Oven Cleaner or EASY-OFF Fume Free Max Oven Cleaner. (Use the fume-free one so you can breath.) Just spray the parts thoroughly, let set a few hours or overnight, then blast the grime and debris off with a high pressure (water) washer. Pressure from an ordinary garden hose just won't cut it. After cleaning, blow dry the parts and be sure to coat the bare metal with oil so they won't rust. If oven cleaner won't work, take the cast iron and steel parts to an automotive machine shop and have them "hot tanked" and have the aluminum parts sandblasted. I don't suggest sandblasting cast iron engine blocks or related parts because some of the sand can become lodged inside the engine and come loose when the engine is in operation, causing severe internal engine wear. Personally, I just coat the parts with oven cleaner and then blast the dirt off with my 1,000 psi water pressure washer.

How to Get More Power Out of a Stock Engine -

It takes three things to make an internal combustion engine run: compression, carburetion and ignition. There's three things that make an internal combustion engine run: Carburetion, compression and ignition. Fuel needs to get to the carburetor and then into the engine. The engine needs to have adequate compression to fully compress the air/fuel mixture to make power. And the ignition needs to be strong enough to ignite the air/fuel mixture. The ignition timing must also need to be set correctly to ignite the air/fuel mixture precisely at 20 BTDC to take full advantage of the exploding gases. Actually, it takes four things to make an engine run, including the starting system. If an engine won't start or if it's hard to start, and it has adequate compression, the carburetor and ignition seems to be working fine, then the only thing left is the starting system. Perhaps the starter motor or battery is going bad. They probably appear to be operating normal, but maybe one or the other isn't cranking the engine over fast enough to produce adequate compression to start the engine. I've seen this happen a few times. But if the compression, carburetion or ignition is weak or defective, power will be decreased dramatically. When checking for loss of power, always check the following things: Carburetion is when an adequate amount of fuel and air enters an engine smoothly. Check the ignition timing. Chances are, if the timing isn't advanced enough, the engine will lose power and run sluggish. Check for a worn points lobe on the camshaft, too. Compression is when the air/fuel mixture is adequately pressurized in the combustion chamber on the compression stroke. The secret to gaining more horsepower and torque is increase the compression ratio and improve the air flow in and out of the combustion chamber. Another way to gain more power from the high rpm is to install a special camshaft along with larger diameter valves, stiffer valve springs and porting/polishing the intake and exhaust runners. Apply epoxy (such a J-B Weld) inside the intake port and smooth it so the air will flow without any restrictions into the combustion chamber. This works great. But before applying the epoxy, make sure the port is absolutely clean or the epoxy won't bond to the engine block. and a few other things that's mentioned elsewhere in my pulling tips web pages.

FYI - When everything that's mentioned here is performed to an engine, it should produce maximum power. But if just a few things are performed, the power will be increased, but not to the maximum. For example: if the valves are reworked for more airflow, then the intake and exhaust runners would also need to be enlarged, and the carburetor would need to be bored to take full advantage of the maximum airflow. But if the intake runner isn't enlarged, this would create a "bottle neck," and air will be restricted. The same goes for the valves and carburetor. Also, if a cam with more duration is installed, then the valve and air intake system would need to be maximized to take full advantage of the performance camshaft. But if just the cylinder head is milled, and nothing else is done to the engine, this alone should add a few ponies to an engine. The same goes when just popping the piston out of the cylinder. Each time a performance thing is done to an engine, power output will be increased. But if a series of things are performed, such as maximizing the air intake system, they can work together for better engine performance.

When it's time to put more muscle in your engine...

In order for an engine to turn at extremely high rpms (6,000+), the compression ratio and air flow in and out of the combustion chamber must be increased to the maximum. The secret to increased engine performance is to get as much air (and fuel) into the combustion chamber, and get it out as quickly as possible. (Remember - engine performance is entertainment to the spectators.) For the compression ratio to be increased, the air entering the combustion chamber must be squeezed as tight as possible. To raise the compression and increase the air flow on a flathead engine....

1. Mill the stock cylinder head .050", or mill out a specially designed combustion chamber in a billet aluminum head so the air can be squeezed tighter. Click here for more info on this.

2. Pop the piston out of the cylinder a few thousands of an inch. Doing this is the same as using dome pistons in an over head valve engine. Click here for more info on this.NOTE: the cylinder head can be milled .050" and the connecting rod offset .020" for piston pop-out. Being the cylinder head gasket has a compressed thickness of .050", this will give the top of the piston a safety margin of .030" clearance.

3. Install a special camshaft with increased duration and valve lift. Cams with increased duration holds the valves open longer to trap the air in the combustion chamber at higher rpms. This builds up more compression in the combustion chamber. Click here for more info on this.

4. Install oversized intake and exhaust valves, along with offset valve guides, or at least for the intake valve. At very high rpms, a bigger intake valve will allow an engine to draw more air (and fuel) into the combustion chamber, and the bigger exhaust valve will allow quicker and easier exiting of the exhaust gases. In a high-compression and high-rpm engine, air must pass through the combustion chamber very quickly with no restrictions. Bigger valves will allow this. More air that's crammed into the combustion chamber means higher pressures, higher rpms and more power. The offset guides will move the valve head(s) closer to each other and closer to the piston, to retain (with a stock head) or create (with a billet head) a smaller combustion chamber so the air can be squeezed tighter in the combustion chamber. Click here for more info on this.

5. Enlarge and smooth the ports in the intake and exhaust runners. In addition to the larger valves and bigger cam, porting and polishing will also allow an engine to pass more air (and fuel) through the combustion chamber. Otherwise, this area would have restricted airflow or be a "bottleneck" and very little will be gained. Click here for more info on this.

6. Apply epoxy (such a J-B Weld) inside the intake port and smooth it so the air will flow without any restrictions into the combustion chamber. This works great. But before applying the epoxy, make sure the port is absolutely clean or the epoxy won't bond to the engine block.

7. In addition to the bigger cam, larger valves and ports, the venturi that's inside the carburetor throttle bore must be removed, or a larger carburetor can be used. Doing this will also allow an engine to draw more air (and fuel) into the combustion chamber. Use of an unrestricted air filter or a velocity stack will help, too. Click here for more info on this.

8. Increasing the length of the piston stroke in the cylinder will also increase the compression ratio.

The only things that can cause an engine to overheat and loose power are as follows:

Clogged cooling fins or broken fins on the flywheel Too high compression ratio for the grade of gas being used Ignition timing advanced too much Lean fuel mixture Vacuum leak at the carburetor, which will also cause a lean fuel mixture.

How To Get Maximum Horsepower and Torque from a "Basically Stock" Kohler 10-16hp K-Series or Magnum Engine -

Approximately 48% more horsepower and torque can be produced from a basically "stock" single cylinder flathead Kohler engine. This means that approximately 15hp can be produced from a 10hp, 17hp from a 12hp, 20hp from a 14hp and 23hp from a 16hp governed engine at 4,000 rpm (the factory setting of maximum rpm for virtually all small gas engines, including all of Kohler engines is 3,600) on Premium gasoline! And if the majority of the fins are removed from the flywheel, or if a steel flywheel is used, this will add about 3-4 more hp per engine! Also, about 10% to 13% more power can be produced with E-85 or methanol fuels! Click here for information regarding E-85 fuel. The above figures was computed using Mr. Gasket's DeskTop Dyno computer application. (Do a search on the Internet for this application.) And even more power can be produced above 4,000 rpm! But be sure to install a billet steel flywheel, connecting rod and scatter shields whenever running an engine above 4,000 rpm! The compression ratio must be increased in order to increase the power output. Click here for references to various compression ratios. After modifications have been made, the increase in power will definitely be noticeable! Rather if it's used for pulling competitively or just for yard work, a "built to the max" stock engine will perform much better with the modifications listed below...

Here's Some Basic External and [Fairly] Low Cost Performance Improvements That Can Be Done:

1. Perform a quality tune up. Install new ignition points, condenser and spark plug. Set the ignition timing at 20 BTDC. Don't trust a feeler gauge in the point gap. Use an ohm meter or test light (with the engine not running) or an automotive inductive timing light (with the engine running).

2. Index the spark plug. This is when the open gap faces the piston. It helps to produce a little more power, especially at higher rpms.

3. Only on the 10-16hp flathead Kohler engines, mill the stock cylinder head approximately .050" to increase the compression ratio. Remove just the "ridge" that mates with the head gasket. This is when approximately .050" of metal is removed from the raised gasket mating surface. To guarantee that the head is absolutely parallel, this must be done on a vertical milling machine with a flycutter and not on a sanding disc. Use the sanding disc only if a head is warped. If it is warped, have it resurfaced on a flat sanding disc or belt sander until it's perfectly flat. Milling of the head (remove the raised ridge that mates with the head gasket) will increase the compression ratio about 3/4 of a point, and depending on engine size, resulting in about 1-3 more horsepower. Reworking the valves so they'll clear the head may also need to be done. In most cases, there should be adequate clearance once the head is shaved. Always check the clearance when the valves are at full lift before "shaving" a head! NOTE: Do not mill the head to increase the compression on the 7hp and 8hp cast iron block Kohler engines. Because on these heads, the clearance is already very close between the valves and head. If it's warped, have it resurfaced on a flat sanding disc or belt sander. Or install a high compression, "LP" cylinder head. For more information, click HERE. (NOTE: This may not be a low cost improvement if you're purchasing one of these heads off eBay.)

4. Perform a quality valve job. Grind a 30 angle on the face of the intake valve and seat only, and undercut and swirl-polish the intake valve head so more air/fuel will enter the combustion chamber. Because any restriction of the intake system will cause an engine not to produce more power. And for the exhaust to exit the combustion chamber quickly, grind a 45 angle and undercut the exhaust valve head. Because any restriction of the exhaust system will cause an engine to lose power. Click here to learn how to do a professional valve job. Set the valve lash (clearance) at .010" for the intake and .014" for the exhaust. Make sure that the ends of the lifters and valve stems are ground square for proper adjustment.

5. For ordinary yard use, heavy towing, garden tilling, snow removal, etc., for a 10hp and 12hp engine, install a #30 (1.2" throttle bore) carburetor. (The #30 or 1.2" bore) carburetor originally comes on the 14hp and 16hp engines.) Either a Carter, Kohler or Walbro carburetor will work equally as well. Or have a #26 Carter or Kohler carburetor bored. (A #26 carburetor will flow more air than a stock #30

carburetor.) Rework the carburetor (bore out the venturi, grind the main nozzle, etc.) as described in my carbfuel.htm web page.

6. Enlarge the ports the same size as the carburetor throttle bore (only if the carburetor have been bored out) and polish (smooth) the intake and exhaust runners. Just smooth up the exhaust port and remove any rough casting slag.

7. Being there's no long intake tube for the gas to atomize in before it reaches the combustion chamber, the Kohler OEM thick carburetor mounting gasket (which is actually a piece of plastic-like material sandwiched between two gaskets) isolates the carburetor from the engine heat so the gas will atomize better when it before it enters the combustion chamber. Atomized gas vapors mixes with the air better, and make the engine produce more power.

8. For up to 4,000 rpm, you can either re-use the stock OEM valve springs, or to reduce "valve chatter" and to insure proper valve action, install new OEM springs. And it's safe to re-use the OEM retainers and keepers. To reduce valve float and loss of engine power above 4,000 rpm, use the "lightweight" valve springs (slightly stiffer than OEM) from either Lakota Racing (http://www.lakotaracing.com), Midwest Super Cub (http://www.midwestsupercub.net) or Vogel Manufacturing Company (http://www.vogelmanufacturing.com). If you use stiffer springs, the camshaft could break and/or the center of the valve heads may collapse overtime.

9. For pulling competition only, remove or disable the operation of parasitic accessories from the engine (which robs horsepower and causes drag on the engine), such as the starter/generator, alternator charging system, and including reducing the height of the fins by about 3/4 or removing all of the fins from the flywheel. (Personally, I use a reciprocating saw to remove about 3/4 of the height of the fins on my Kohler flywheels. And I ALWAYS have the flywheel dynamically precision balanced afterwards!) The generator part of the starter/generator unit and the alternator system uses about 1-3hp of engine power when it charges the battery at a full 15, 20 or 30 amps with the engine running at 3,600 rpm. So to conserve this power for pulling, disconnect the generator or alternator from charging the battery (and powering other accessories as well) simply by splitting the wire that connects to the FIELD terminal (the smaller wire and terminal) on a starter/generator unit and splitting the wire that connects to the center terminal on the voltage regular of an alternator system. Then connect an ordinary OFF/ON toggle switch in that wire or circuit to turn off and on the charging current. And it'll be best not to spin the starter/generator when pulling. It can use up to 2hp just to spin it. Install a heavy spring on the generator/starter so it'll remain close to the engine. To start the engine, install the belt on the pulleys, then pull out on the generator/starter with a fabricated handle to tighten the belt. After the engine starts, flip the belt off. But use caution doing this for an obvious reason! The wasted energy that's needed to spin the starter/generator needs to be put to the ground. Besides, wouldn't it be better to spin the tires than the starter/generator?

Remove the flywheel fins ONLY if an engine is governed up to 4,000 rpm, and absolutely have a [cast iron] flywheel dynamically precision-balanced afterwards! If an engine is going to be operated well above 4,000 rpm (with no functioning governor), and rather if your pulling club's sanctioning rules require one or not, definitely install a steel flywheel (with no fins). Click here to see what can happen to an unaltered 9-1/2" diameter cast iron Kohler flywheel when spun well above 4,000 rpm.

You can have your Kohler flywheel and crankshaft/piston/rod assembly professionally dynamically precision balanced at:

JD Engine & Machine, 900 Spencer St., Columbia, Missouri 65201 | Phone: 573-445-4550 Lakota Racing (http://www.lakotaracing.com/) Midwest Super Cub (http://www.midwestsupercub.net/) Precision Machine, Inc., 1703 Christy Dr., Jefferson City, Missouri 65101 | Phone: 573-635-7214 Vogel Manufacturing Co. (http://www.vogelmanufacturing.com/)

But if you want more power out of your engine, more internal work is involved....

1. First, completely disassemble the engine and then... Being the connecting rod will need to be fitted with bearing inserts, you can gain two things at one time by having the rod bored .020" offset (towards the dipper). This will pop the piston out of the cylinder approximately .020" and the rod will have a protective bearing. It'll cost a lot less to have it done this way, too. If you want, I can install a bearing in your Kohler connecting rod(s). Please click here for more information. Bearing inserts that I install in Kohler connecting rods can be used for ordinary yard work or for pulling competitively. Click here to learn how to install bearing inserts in a rod. When installing the rod and piston in the block and after the rod is connected to the crankshaft, sometimes there can be a clearance problem with the rod hitting the edge of the cylinder. That's because of the offset of the bearing in the rod. To fix this problem, just grind away part of the cylinder wall until the rod clears it.

2. If there's carbon covering the top of the pistons, this means that the engine doesn't burn much oil, if any. But if there's some oil on top of the pistons and some of the carbon is washed clean, this is an indication of oil burning and the engine needs to be rebuilt. If your engine doesn't produce blue smoke out the exhaust (doesn't burn oil), then it should be okay to reuse the same piston and rings. Because there's probably not that much wear on them. When reinstalling a used piston/rings though, oil the rings and install the piston with the ring gaps set 180 apart. But if your engine does smoke and use oil, it'll be best to have the cylinder measured for wear and perhaps bored to the next oversize, or if it's within tolerance, just install a new STD size piston and rings assembly.NOTE: I have some bad news concerning Mahle pistons! I was told by several sources that they're supposed to be made of tougher material than ordinary K-series pistons, but I found that they are not! I have personally taken apart several Magnum engines that was used in ordinary lawn mowing equipment, and I found that these pistons wear out sooner than the K-series pistons. So in my opinion, I think that Mahle pistons are junk and overpriced. You'll be much better off using an OEM Kohler K-series or an aftermarket import piston & rings. They last a lot longer than any Mahle piston that I've ever seen.

3. Due to the increase in the compression ratio, which places more strain on the connecting rod, you'll definitely need a stronger rod, but only if your (12hp or 14hp) engine doesn't already have one. To tell if your engine has a stronger 16hp rod, it'll be of one solid color. The "two color" rods (light gray at the wrist pin and dark gray at the crank pin) are probably too weak for a "built to the max" stock engine. The 2 color rods were dunked in an acid bath and tin plated. Core product parts are no longer being made. I noticed that Kohler hasn't sold the 2 color rods in a long time. All that's available nowadays All that's available nowadays for a 12, 14 and 16hp engine from a Kohler dealer is a one color [16hp] rod, which I think is much stronger. It seems that the 12hp, 14hp and 16hp Kohler engines came with 6 (I think) different connecting rods. They were obviously made by various manufacturers. Why? I have no idea. I know that the rods with studs seems to be stronger, or hold up at higher rpms, than the ones with bolts. Although some of the rods with bolts seem to hold up very well at high rpms, too. And I know that the "two color" rod is questionable about holding up at high rpms. (High rpms = 6,000+ rpms)And the ALCOA connecting rod that originally came in all 18hp OHV (K361) engines are even stronger yet. And as far I've seen, most of the 14hp and 16hp rods are the same. Although some 14hp's (and 12hp's) came from the factory with the weaker "two color" rod. But some 12hp's also came from the factory with the stronger 16hp rod. And ALL 18hp rods are made of forged aluminum alloy. They're the strongest of any rods that's used in Kohler engines. If you're going to turn your engine no faster than 4,000 rpm, an ordinary 12hp or 14hp "two color" rod should suit it just fine. But higher rpms requires a stronger rod. 16hp rods are good for up to around 6,000 rpm. But the 18hp rod is good for well above 6,000 rpm. By the way, the new 16hp rod is designed for the new-style 16hp piston, but it'll work with any 12hp or 14hp piston with no problems. Also, all 16hp rods come with a long oil dipper. So if you're using a flat bottom oil pan, you'll need to cut half of the dipper off with a hacksaw and smooth up the rough

edges with a flat file. Be sure to sharpen the edge of the dipper with the file so it'll slice through the oil with less resistance. It'll still provide plenty of lubrication, too. (A "blunt" dipper has a tendency to rob horsepower.) And it's safe to reuse a stock rod in a 10hp engine. They're strong rods. And being the engine is going to be operated at a maximum of 4,000 rpm, there's no need for bearing inserts.

4. If using for a pulling engine, I recommend using a 16hp or 18hp rod for strength and durability. There's three reasons why a connecting rod breaks. 1) lack of lubrication; 2) too high rpms; 3) metal fatigue. A stronger rod will hold up to very high rpms as long as the piston/rod assembly and crankshaft counterweights are precision balanced, and if the rod is made of durable material, it'll overcome metal fatigue.

5. Install an OEM camshaft that's originally made for Kohler's model K361 18hp Over Head Valve engine. NOTE: The "18hp cam" originally came in the model K361 18hp single cylinder Kohler engine that have the valves in the cylinder head but the camshaft in the crankcase. This particular cam has the same lift as the 10-16hp flathead engine cams (.324"), but increased duration from 223 (flathead cam) to 256 (18hp OHV cam), which will produce more power and torque at 4,000 rpm when used in a flathead engine. This particular cam makes it's most power and torque up to 4,000 rpms, which works great in a stock engine. If an engine is going to be turned faster, then a cam with more lift and duration should be used for best performance. And when installing this cam, align the timing marks (on both the crankshaft teeth and cam teeth) as you would with virtually any other engine, and use a thick shim (.010") and/or a thin shim (.005") on the flywheel end so the cam will be in proper time in relation with piston travel. It's important that the compression relief mechanism on the camshaft is functioning properly, too. The compression relief mechanism is required to relieve some of the higher compression at cranking speeds so the engine will crank over easy to start it. FACT: The 18hp OHV cam works so well in the 10-16hp flathead engines, many clubs are outlawing it in their stock class(es). And to swap out the cam, you must first disassemble the entire engine. The pin that the cam rides on must be driven out from the PTO side of the block. (It comes out toward the flywheel end.) VERY IMPORTANT - Before installing any Kohler camshaft, be sure to lubricate the pin and the inside of the camshaft before reinstalling! And if the base of the lifters aren't worm or scored, they can be re-used. By the way - the lifters in the 10, 12, 14 and 16hp flathead engines and the 18hp OHV engine are all the same. The 18hp camshaft comes with a compression relief. By the way - the 18hp cam doesn't have enough duration to make the engine have a "loping" sound at idle. It makes the engine sound like a stock short-duration cam.NOTE: Use stock OEM valve springs with a stock OEM or 18hp cam if an engine is going to turn 4,000 rpm or below. And use Stock-Altered (single) valve springs for above 4,000 rpm. Because cast iron is brittle, do not use double (Super-Stock) valve springs with the 18hp or any [welded up] OEM camshaft! Also, with double springs, the compression release tang on the cam could break off. And be gentle when handling a cast iron camshaft! If the cam is mishandled, the lightweight spring that controls the compression release mechanism could come off the levers when installed in the engine. If this happens, the engine would crank over under full compression, making it very hard or impossible to start.Actually, there's no reason to use heavy springs because the 18hp cam has the same lift as the stock OEM flathead cams. And the .005" and .010" shims are for proper valve timing in relation to piston travel, not gear alignment. New 18hp OHV camshaft with a working compression relief mechanism. The 18hp OHV single cylinder cast iron block Kohler engine camshaft will help the 10-16hp K-series and Magnum flathead engines to produce more power and torque up to 4,000 rpm because it has the same lift, but more duration.To check the rpms of an engine that has an 18hp cam, first of all, with the Dixson handheld tachometer, flathead cams will show half the rpm because the points fires every other revolution. You must double the reading for the exact rpm. But with the 18hp cam, the points may fire every revolution. Therefore, when checking the rpms, the reading will be exact.The OEM 18hp cast iron camshaft (originally came in the Kohler 18hp OHV model K361 engine) is no longer available from Kohler. If you need a new cam from old stock, the part number is 45 010 05S. They retail for about $115.00. If you're lucky,

you can still get one from your local factory authorized Kohler engine dealer, or get a duplicate 18hp cam from Lakota Racing, or get a "Cheater" stock pulling cam (which has more duration than the 18hp cam. The duration is: Exhaust: 276, Intake: 300.) from Vogel Manufacturing Company. Or you can have Madson's Service, Inc. (Madson's Service, Inc., 114 S. 2nd Ave., Saint Nazianz, WI 54232-0000 Phone: 920-773-2661 Email: madsonsservice@tds.net.) regrind your 10-16hp OEM flathead engine cam to the Cheater specs for $85.00 (as of 1/5/09), plus return shipping.The 18hp cam works great for increased power in a 10hp and 12hp engines, but it won't do quite as much in the 14hp and 16hp engine because of more cubic inches. Although it will work great in the 14hp and 16hp engines, but it creates less noticeable power increase in the 14hp and especially the 16hp engine. However, it does help in the power increase in a 16hp, it's just less noticeable because of the bigger cubic inch displacement. A "mild-performance" cam, such as the 18hp cam, works better in engines with smaller cubic inches. A somewhat bigger cam is required as the cubic inches are increased. Because bigger engines needs to draw in and expel more air (at 4,000 rpms with stock valves), and the 18hp cam has it's limits when used in the bigger engines. And because of it's short lift and duration, it makes it's most power up to around 4,000 rpm.

6. If your engine is going to be fitted with larger (oversize) valves, then remove (bore) the venturi from

the carburetor, and grind a 45-60 angle on the main nozzle toward the choke end as described in my carbfuel.htm web page. Leave everything else alone on the carburetor, unless of course you're going to use it for pulling competition.

7. You can use the engine modifications in this web page for everyday use as well for competitive pulling. But you'll have to burn Premium gas, high-octane race gas, E-85 or methanol fuels in your engine to prevent premature wear due to a higher operating temperature. Click here for information regarding E-85 fuel.

Briggs and Stratton, Tecumseh, Onan and Kohler's cast iron block 7hp and 8hp, and the twin cylinder flathead engines are all somewhat limited on what can be done to boost their horsepower and torque. These engines are built from the factory to produce as much power as they possibly can, and still run safely on low octane gasoline. Therefore, very few modifications can be perform to help increase the power output. The only alternative is to use a bigger engine. But doing the things below should boost the horsepower of these engines about 2-3hp more at 4,000 rpm.

1. Deck the block .020" so the piston will pop out of the cylinder approximately .020". 2. If the cylinder head is warped, have it resurfaced on a flat sanding disc or belt sander till it's perfectly

flat. Don't have it milled. The valves could hit the head if it's milled. Use a stock OEM or stock-thickness copper head gasket.

3. Port and polish the exhaust and intake ports. Open up the ports so the engine can breath more air at higher rpms.

4. Give the intake valve face and seat a 30/31 angle, respectively. Grind the exhaust valve and seat at factory specs (45/46, respectively).

5. High-performance camshafts are available for some of these engines, but not all. Either reuse the stock cam or have it reground for more lift and duration.

6. Set the intake valve lash (clearance) at .010" and the exhaust at .014". Make sure that the ends of the lifters and valve stems are ground square for proper adjustment.

7. No billet connecting rods or bearing inserts are available for the B&S and 7hp and 8hp Kohler engines that I know of. Strong OEM stock connecting rods originally come in all Briggs & Stratton engines and the 7hp and 8hp Kohler engines. If the rotating parts are precision balanced, and if the rod is honed for an additional .001" of oil clearance, then stock OEM rods can be safely ran at high

rpms without bearing inserts. 8. Use 20W50 full synthetic motor oil to help keep the rod and crank journal cool at high rpms, Click

here to learn about different types of motor oils. Aftermarket connecting rods for bigger Tecumseh engines are available from Greg Edwards of Waynesboro, VA | Phone: 434-996--5549 | E-mail: sdrawde@ntelos.net.

9. No high performance modifications can be made to the 7hp or 8hp Carter model N carburetor. Just use it the way it is Except that a carburetor off an 8hp Kohler engine can be used on a 7hp Kohler to slightly increase the performance because the 8hp carburetor has a larger venturi. Or, for a little more performance, fabricate an adapter, open up the intake port and install a stock or 1" [Stock-Altered] #26 Carter or Kohler carburetor.

10.Premium gas, high-octane race gas, E-85 or methanol fuels should be used in these engines after the modifications have been made. Click here for information regarding E-85 fuel.

* The increase in the compression will cause the combustion chamber to operate at a higher temperature. If low octane gas (87 octane) is used, and because low octane gas burns more rapidly than high octane gas, it'll burn hotter in a high compression engine, causing the piston and rings to overheat and wear out much sooner. Therefore, high octane gas (at least 91 octane [Premium]) must be used in a high compression engine because it burns slower and it maintains a cooler operating temperature within the combustion chamber. It'll help the engine last longer plus the high octane gas will help to produce more power. Also, it's safe to use just ordinary unleaded [high octane] gasoline with no additives (except what's already been formulated with the gasoline at the pump). Premium gasoline is the highest octane automotive gas you can get at your local filling station or convenience store.

High compression engines naturally operate at a higher operating temperature. So when using low octane gasoline (87 octane rating) in a high compression engine, the octane of the gas is reduced by 1 point for every 10 above the operating combustion chamber temperature that it is formulated for. This will cause the gas to burn faster and cause the engine to lose power. "Detonation" (pounding of the piston) could also occur. When trying to restart an overheated high compression engine on low octane gas, what is happening is the gas is burning quickly and entirely in the combustion chamber, and producing expanding heat before the piston reaches TDC, driving the piston back down in the cylinder before it reaches TDC. It'll cause the engine to "runt, runt" or momentarily make the crankshaft rotate in the opposite direction (but the weight of the flywheel prevents this from happening). Overheating could also crack the [cast iron] cylinder, shrink the piston, burn a hole in the piston (detonation) and weaken the expansion of the piston rings. Methanol fuel has an octane rating of 135. This is why methanol works best in high compression engines.

If you have a stock, low compression engine, then it won't benefit whatsoever from using high octane fuel. All it'll do is waste fuel (some of the fuel will go unburned and exit out the exhaust) and the engine won't develop full power, even with advanced timing. So it's best just to use low octane fuel for best performance.

In an ordinary engine that's built-to-factory-specs (with no modifications), it's OK to use just 87 octane gasoline. If you were to use high octane gas in a low compression engine, you'll just be wasting money and gas. Because some of the gas will go out the exhaust unburned, with no increase in horsepower whatsoever.

The initial setting for proper operation of the governor for stable engine speed is first loosen the clamp nut on the governor lever and rotate the shaft counterclockwise with the throttle in the full throttle position. Then tighten the nut. After you start the engine, run it a full (governed) speed and select the hole in the governor that allows the engine to run at 3,600 rpm.

Plastic governor gears works best if an engine will never run above 4,000 rpm. But if you're going to pull competitively with an engine and disconnect the governor to run the engine at wide open throttle, then it's best to install a cast iron governor gear. Because plastic will explode due to the increased rpms.

If you want to do away with the governor, you must remove it entirely from inside the engine block. Otherwise, at high rpm, the flyweights that's attached to the governor gear (which is called the "governor spool") will cause the plastic spool to explode. Or, you could disconnect the governor link from the carburetor and wire the arm to the exhaust pipe. This will prevent the governor spool from being damaged at high rpm. But then you must fabricate a throttle linkage of some kind to activate the throttle on the carburetor. For safety reasons, install a steel flywheel and crankcase side shields on an engine with no operating governor!

If you need even more power, remember the old saying? "There's No Substitute for Cubic Inches!"

If you're running a 10hp (K241) Kohler engine in a class that allows up to a 12hp engine, there's no need to go out and acquire a 12hp block, and then have all the fancy machine work that was originally done on the 10hp block. Instead, a 10 can be easily converted into a 12 by having the cylinder bored for a 12hp piston assembly, a 12, 14, 16 or 18hp connecting rod, and a 12hp crankshaft.

NOTE: Some 10hp Kohler engine blocks have the characters K301 embossed in the casting above the PTO end. These blocks have a thicker cylinder wall and can be safely bored for a 12hp piston (even up to .030" oversize), without making the cylinder wall too thin. In other words, they're like the 13-fin 16hp block.

The K301 blocks with a 10hp bore can be safely bored for use with a 12hp piston. The K301 blocks are actually a 12hp block with a 10hp bore. There's nothing special about this blocks, except for the thicker cylinder wall. They weren't used in any "heavy duty" specific purpose either. What happened is on the production line at Kohler, when they ran out of 10hp blocks, they grabbed a bunch of 12hp blocks and bored them for use with a 10hp piston to finish the production of a bunch of 10hp engines. And not all Kohler blocks that have the K301 characters are actually 10hp blocks. Some are bored for a 12hp piston assembly (3.375" STD bore) and therefore, are a 12hp block. The ones that are bored for a 10hp piston assembly (3.250" STD bore) have a thicker cylinder wall and therefore, are a 10hp block. To determine which block is which, the diameter of the cylinder bore needs to be accurately measured.

How to Create a Generic Model "K261" Kohler Engine -

If the cylinder wall in a 10hp (model K241/M10) engine block is severely gouged or has excessive deep grooves and can't be bored enough to clean up for use even with a .030" oversize 10hp piston, and installing a sleeve for a standard size 10hp piston is too costly, then the block can be bored for use with a STD size 12hp (K301) piston/rings assembly. A 10hp connecting rod (a 12, 14, 16hp or 18hp ALCOA rod cannot be used for this purpose) and 10hp crankshaft is to be reused, creating a 26 cubic inch engine, a generic model K261, or a "de-stroked" 12hp engine.

If built to stock specs, it'll produce about 14hp at 4,000 rpm. But if it's built to the max, it'll produce about 22hp at 4,000 rpm. For strength and durability, especially if it's built to the max, it's best to use a 10hp block with K301 embossed on the PTO end, like the one pictured above. These particular blocks have an extra thick cylinder wall. A 10hp crankshaft can also be used in a 14hp (K321/M14) or a 16hp (K341/M16) block, creating generic models K281 and K321.

Here's how to make it happen:

The big end of the connecting rod will need to be bored .070" offset toward the wrist pin hole so the piston will come flush with the top of the block. With the .070" offset, it's best to use a .010" undersize rod for a full circle cut. If using a STD size rod, use J-B Weld to fill in the uncut portion of the rod hole, allow the J-B Weld to fully cure (harden), then resize the hole so it'll be a perfect circle again. Or the rod can be bored .050" offset toward the wrist pin hole for a .020" piston pop-out. Bearing inserts will need to be installed.

The wrist pin hole in the same rod will need to be enlarged to exactly .8755" for use with the 12hp (or 14, 16hp) piston's wrist pin.

Being a heavier piston assembly is to be used, the crankshaft (rotating assembly) will need to be rebalanced, or the engine will vibrate severely and possibly self-destruct. This means that weight will need to be added to the counterweights on the 10hp crankshaft so the rotating assembly will be properly balanced. Click here to learn how to statically balance an engine.

If building this type of engine for competitive pulling, check with your club's sanctioning rules so this type of engine will be legal within its class.

How to Create a Generic Model K271 Kohler Engine -

To create a model K271 Kohler engine, use a 10hp (K241/M10) block with a 10hp piston/rings assembly, and a 12, 14, 16hp [flathead engine] connecting rod or an 18hp OHV ALCOA rod (a 10hp rod cannot be used for this purpose) and a 12, 14, 16hp flathead or an 18hp OHV engine crankshaft. This combination will create a 27 cubic inch engine, a generic model K271, or a "stroked" 10hp engine.

If built to stock specs, it'll produce about 11-1/2hp at 4,000 rpm. But if it's built to the max, it'll produce about 16-1/2hp at 4,000 rpm. For strength and durability, especially if it's built to the max, it's best to use a 10hp block with K301 embossed on the PTO end, like the one pictured above. These blocks have an extra thick cylinder wall.

Here's how to make it happen:

The big end of the connecting rod will need to be bored .080" offset toward the oil dipper so the piston will come flush with the top of the block. Or it can be bored .100" offset toward the oil dipper for a .020" piston pop-out. With either offset, it's best to use a .010" undersize rod for a more complete circle cut. Use J-B Weld to fill in the uncut portion of the rod hole, allow the J-B Weld to fully cure (harden), then resize the hole so it'll be a perfect circle again. Bearing inserts will need to be installed.

The wrist pin hole in the piston will need to be enlarged to exactly .8755" for use with the 12, 14, 16hp flathead or 18hp OHV ALCOA rod's wrist pin, or the wrist pin hole in the rod can be reduced with a bronze bushing i.d. of .8594" (55/64") for use with the

10hp piston's wrist pin.

Being a heavier crankshaft is to be used, the crankshaft (rotating assembly) will need to be rebalanced, or the engine will vibrate severely and possibly self-destruct. This means that weight will need to be subtracted from the counterweights on the crankshaft so the rotating assembly will be properly balanced. Click here to learn how to statically balance an engine.

The lower sides of the cylinder wall may need to be clearanced (ground away) for the connecting rod due to the longer stroke.

If building this type of engine for competitive pulling, check with your club's sanctioning rules so this type of engine will be legal within its class.

How to Build a 30 Cubic Inch (NQS Outlaw) Pulling Engine -

To build a "somewhat" competitive 30 cubic inch pulling engine, acquire a newer 12hp Kohler block with a large intake port, have the cylinder bored to .050" oversize for a 3.425" aftermarket (J&E or Arias) piston/rings assembly, and use a stock stroke (3.250") crankshaft. This bore and stroke combination calculates to 29.94 c.i. (Install a 1.8" offset intake valve and a 1.5" offset exhaust valve, big steel cam, billet head, and use a 44mm Mikuni carburetor with about an 8" long extension.) The piston and rod combination to use for this particular bore and stroke are as follows:

Piston compression height of .875", with an aftermarket billet connecting rod of 6.125" in length will bring the piston flush with the top of the engine block. No rods are available for a piston pop out with this particular piston.

Piston compression height of 1", with an aftermarket billet connecting rod of 6.000" in length will bring the piston flush with the top of the engine block. For a .062" pop out, use a 6.062" rod. For a .125" pop out, use a 6.125" rod.

Piston compression height of 1.125", with an aftermarket billet connecting rod of 5.875" in length will bring the piston flush with the top of the engine block. For a .062" piston pop out, use a 5.937" rod. For a .125" pop out, use a 6.000" rod.

But to build a truly competitive 30 c.i. pulling engine, use a 10hp/K241 Kohler block. (Acquire a 10hp block with K301 embossed on the PTO end, for strength and durability, like the one pictured above.) The cylinder will need to be bored to 3.300" and a steel crankshaft with a stroke of 3.500" will need to be used to build a stroker 29.94 cubic inch engine. (Install a 1.8" offset intake valve and a 1.5" offset exhaust valve, big steel cam, billet head, and use a 44mm Mikuni carburetor with about an 8" long extension.) The piston and rod combination to use for this particular bore and stroke are as follows:

Piston compression height of .875" with an aftermarket billet connecting rod of 6" in length will bring the piston flush with the top of the engine block. For a .062" piston pop out, use a 6.062" rod. For a .125" pop out, use a 6.125" rod.

Piston compression height of 1" with an aftermarket billet connecting rod of 5.875" in length will bring the piston flush with the top of the engine block. For a .062" pop out,

use a 5.937" rod. For a .125" pop out, use a 6" rod. Piston compression height of 1.125" with an aftermarket billet connecting rod of

5.750" in length will bring the piston flush with the top of the engine block. For a .062" pop out, use a 5.812" rod. For a .125" pop out, use a 5.875" rod.

Due to the small bore and long stroke, this combination produces more torque at high rpms (wide open throttle) than building a 12hp block with a .050" overbore and stock stroke (3.250") crankshaft. If the engine is built right, and if the correct camshaft and gearing is used, it'll give the competition a kick in their butt! No joke. Use the same size valves, cylinder head and carburetor as the stock stroke engine above. This bore and stroke combination is legal in the NQS's rules, as long as the cubic inch displacement does not exceed 30. With the 3.300" bore and 3.500" stroke, the cubic inches will be 29.94. But to be closer to 30 cubic inches, have a STD crank journal ground .015" offset, resulting in a .030" undersize journal, lengthening the stroke to 3.5075". The results with the 3.300" bore and a 3.5075" stroke, the cubic inches will be 29.999, which is slightly under the legal limit. Doing this will gain an edge over the competition. Click here for an explanation of why a longer stroke works better.

Gain More Power and Torque by Moving the [16hp] Piston Closer to the Valves!

Only the OEM 16hp (K341) and 18hp OHV (K361) Kohler engine blocks, the center of the cylinder bore is offset .250" (1/4") with the centerline of the crankshaft main bearings. Because of the much larger bore, the piston is moved further away from the valves. On OEM pistons, the wrist pin is also located off-center .010" so they'll be less thrust (friction) on the cylinder wall, and this will allow the connecting rod to operate correctly. That's why these particular pistons have a notch in them indicating that the notch must face toward the flywheel.

In a high-performance 16hp engine, if the cylinder is bored in its original location (when the piston is installed off-center), and at high rpms, this will create a lot of friction in the area of the cylinder wall that's closest to the valves. To minimize or reduce this power-wasting friction, have the cylinder bored inline or centered with the center of the main bearings, or closest to the center of the main bearings as possible, depending on the diameter of the piston to be installed. More compression will be produced by doing this, too.

The best way to do this is acquire a [13 fin] 16hp block with an unworn, standard size cylinder. The reason it's best to use an unworn, standard size cylinder is for example, if a 3.825" (.075" oversized) diameter piston is going to be used, the cylinder will need to be bored .030" closer to the valves. The piston will then travel .030" closer with the main bearings. The piston still wouldn't be centered, but it'll be closer than the 1/4" offset. Larger diameter pistons may not be moved this close to the valves though. But it will help greatly in the performance characteristics.

The 13 fin 16hp block have a thicker cylinder wall than the 12 fin block. Therefore, a larger aftermarket piston/rings assembly can be used. And all 10, 12 and 14hp blocks have 13 fins. Only the "thin wall" 16hp block have 12 fins.

Here's something to think about: Between the factory-stock 12hp and 14hp engines, there's 2.19 cubic inches of difference. This means you get 2 more horsepower for that much difference. But between the stock 14hp and 16hp engines, there's a whopping 4.63 cubic inches of difference, for just 2 more horsepower! The reason for this is because the friction that the piston places against the cylinder wall in the 16hp robs the

engine of valuable power. Kohler had to add more cubic inches just to get a maximum of 16hp out of their K341 engine at 3,600 rpm.

And if you're wondering, the cylinder bore is centered in all the [Jones, Julian, etc.] aftermarket blocks.

Do not attempt doing the above on the 10hp, 12hp or 14hp engines! The cylinder on these engines are bored inline or centered with the center of the main bearings. Which should remain this way even for a pulling engine.

Is it worth it moving the piston in a 16hp Kohler? Engines that use a piston or pistons with a notch have an offset wrist pin. The factory had to do this on a lot of big bore engine blocks because the cylinder bore is offset with the crankshaft main bearing centerline. To lessen wear on one side of the piston, the offset wrist pin allows the piston to operate straight up and down in the cylinder and not at an angle.

If it can be done, then it's definitely worth moving the bore closer to the centerline of the main bearings. The aftermarket Stock Altered block has the bore in the stock location (.250" off of the centerline of the crank, toward the starter side of the engine) and is not centered like some must think. Most all the NQS S/A have the bores shifted closer to the valves. By doing this you end up with a tighter combustion chamber for more compression and power. We've done it for a long time on the stock Kohler blocks by offset boring the engine toward the valves, then pressing in a sleeve and offset boring the sleeve. You have to leave about .100 to .125 wall thickness on the sleeve on the valve side to maintain the strength. Depending on how far you move it, the sleeve will show between the fins between the valve box and jug. However, its cheaper just to buy the S/A block and offset bore that, the unfinished bore of a S/A block is only about 3 1/2" so you can offset it quite a bit and still get the bore to cleanup. We paid around $1,000 to sleeve and offset bore an original Kohler block, but it can be done. As far aftermarket blocks that have the bores center over the crank is the Pro/Super Stock blocks like the J2 and others. - This information was provided by Julian Stahl of Midwest Super Cub (http://www.midwestsupercub.net/)

Many people (pullers) believe that an engine will produce more noticeable power and torque simply by boring the cylinder and installing a maximum of .030" oversize piston assembly. But there's really no need to do this, and it won't give it anymore noticeable power. The best thing to do is just bore the cylinder to the next oversize, if needed. Or if it's worn beyond .030", have it sleeved back to standard size.

What makes an engine produce more noticeable power and torque is not necessarily a larger diameter piston, it's having a longer stroke. For example: there's a world of difference in power and torque between a 10hp Kohler engine into a 12hp Kohler engine. Unlike a strong 10hp, a good 12hp engine will actually pull you back in the seat when you punch the gas. Not only because the 12hp has an 1/8" larger bore than a 10hp, but it has a much longer crankshaft stroke, 3/8" longer, to be exact! 12hp engines are able to produce 2 more horsepower than the 10hp because of three things: 1) 1/8" larger bore, 2) 3/8" longer stroke, and 3) higher compression because the 12hp use a cylinder head with the same size combustion chamber as the 10hp. But there's not that much of a noticeable difference in power and torque between a 12hp engine and a 14hp, because the 14hp has an 1/8" larger bore, but it has the same length stroke as the 12hp. 14hp engines are able to produce 2 more horsepower than the 12hp because of two things: 1) 1/8" larger bore, and 2) higher compression because they use a cylinder head with the same size combustion chamber as the 12hp.

A longer-than-stock stroke works better for more engine torque because at very high rpms (wide open throttle), it takes less time for the flame front (combustion) to travel down in the cylinder than it would to

travel across the top of the piston. Therefore, due to the longer stroke, the fuel burns more thoroughly and the engine produces more power from the expanding gases of the burning fuel. For pulling competition, on a short stroke engine, at very high rpms and when the engine is under a load, some of the fuel will go unburned [out the exhaust] and loss of power will result. A short stroke engine works