KTM 530 EXC-R 2008 NO START

1. Spark present

2. Sprayed starter fluid in intake

3. Engine backfired flames through carburetor

2 – Generator 3 – Ignition Coil 4 – Pulse Generator 10 – Throttle Valve Sensor (TPS) 12 – CDI Controller

Partial Wiring Diagram

Cylinder Pressure (WPS-500)

Primary Volts

Secondary Volts

Known Good No-Start

No Spark Present at TDC on Compression Stroke Strong Waste Spark on Exhaust Stroke

Known Good

Pulse Signal Greatly Reduced on Compression Stroke (Waste Spark Signal is Good)

Pulse Generator Signal

No-Start

Pulse Generator Signal

Pulse Generator Connected to CDI Pulse Generator Disconnected from CDI

Pulse Generator Produces Same Low Pulse When Disconnected From CDI (Overall voltage is higher when disconnected from CDI)

What is the cause of this varying pulse height?

Primary Volts (green)

Secondary Volts

Pulse Generator Signal

Generator Voltage Charging CDI

Known Good

Pulse Generator Signal Not Sufficient to Fire CDI on Compression Stroke (8 pulses charge CDI before pulse generator signal on exhaust stroke-no start)

(4 pulses per discharge on known good)

No-Start

Pulse Generator Signal (note the ratio of time for the compression and exhaust pulses i.e. the ratio of shaft speed at these two points of shaft rotation)

Generator Voltage Charging CDI

Compression Exhaust

Time Between Pulses Yields Crankshaft Speed as a Function of Rotation Angle Pulse Generator Signal Yields Shaft Speed at TDC on Compression and Exhaust Strokes

(length and radius of signal tab on flywheel need to be known or estimated) Generator Voltage Signal Yields Average Crankshaft Rotation Speed for 4 Quadrants on Both Compression and on Exhaust Stroke

Crankshaft Speed (RPM) Very Low at TDC on Compression Stroke ~300 RPM (these are average numbers over the quadrant determined from “generator pulses”)

(“pulse generator signal” is more precise and shows an even lower rotation speed at TDC on compression stroke)

Low RPM results in “Pulse Generator” voltage to low to fire CDI, i.e. No Spark at TDC on compression stroke for No Start

588/424

327/351

358/368

397/393

377/363

419/493

380/362

302/391

Red Numbers are for No Start and Black Numbers are for Known Good

RPM at TDC-Compression

RPM at TDC-Exhaust

Cylinder Pressure (WPS-500)

Known Good (2007)

Pulse Generator Signal

Starter Current

Not Connected to Scope

Starter Current Very High at TDC on Compression Stroke for No-Start (average RMS current for no-start about 41% higher than known good)

(starter week and incapable of holding sufficient RPM during compression) (no spark on compression stroke - waste spark on exhaust stroke)

Therefore: NO-START

No-Start (2008)

Compression Ratio: 2008-11.9 to 1 and 2007-11.0 to 1

The Engine is Both Mechanically and Electrically Good (Except for the Starter Motor)

Therefore

The Engine Should Start Using the Kick Starter and

It Starts! (When Kicked Over with the Kick Starter)

Installation of a new starter motor should correct the problem (no-start)

New Starter Motor Did Not Salve the Starting Problem! (luckily I was able to barrow the new starter and battery)

Old Starter and Battery New Starter and Battery

Identical Results with New Starter and Battery

Spark Plug out-Compression RPM~441 Spark Plug In-Compression RPM-216 Known Good Cranking-Compression RPM~397

RPM on Compression Stroke Low Pulse Generator Signal Low CDI Does Not Fire on Compression Stroke No Spark at TDC on Compression Stroke

Will Not Start with Electric Starter

12.7ms or ~441 RPM 25.9ms or ~216 RPM 14.1ms or ~397 RPM

12.6ms or ~445 RPM 14.3ms or ~392 RPM 13.2ms or ~424 RPM

Engine Running

Engine Cranking

CDI triggered

Engine (Crankshaft) RPM Above ~330 to Fire CDI Pulse At or Above ~1.7 Volts to Fire CDI

KTM 450 - 530 Won't Start With E - Starter Problem - Torque limiter Fix How To Article

Around the 50hr mark my 09 530exc developed a problem with the E - starter. The starter

would turn the engine over fine but it wouldn't fire, it would fire right up with the kick

starter though. After doing a lot of reading on the net it sounded like the tor que limiter was

slipping just enough that the engine would turn over but not quite fast enough to light. I

ended up removing the limiter, tightening it up a bit and re - installing it again. Problem

fixed!

The Question: If the starter motor is turning at near a constant RPM, how can the crankshaft RPM be approximately half (~1/2) as fast at TDC

on the compression stroke as on the exhaust stroke?

After some study I found there is a “Torque Limiter” between the starter and the crankshaft!

The “Torque Limiter” could be slipping

(a common problem with this bike)

http://www.advrider.com/forums/showthread.php?t=667644

The following is a very good reference for adjusting the “Torque Limiter”

TDC Compression Stroke

Pulse sufficient to fire CDI on second compression stroke!

Engine running Engine cranking

First crank rotation ave. speed - 317 RPM

Second crank rotation ave. speed - 395 RPM

RPM 1399

RPM 1680

Crank speed during first Exhaust pulse - 412 RPM

Crank speed during first compression pulse - 195 RPM

Crank speed during second compression pulse - 331 RPM

Increased “Torque Limiter” from ~15ft-lbs to 25ft-lbs Engine Now Starts Using Electric Starter!

(Battery is tired and requires a jumper-a new battery will correct this problem)

Pulse Fires CDI Engine Starts

Cold Engine Fires on 5th Crank Rotation and Starts on 7th

Warm Engine Starts on 3rd Crank Rotation (waste spark on exhaust stroke, every second rotation)