Please help me diagnose my WR starting issue..

[Vacman 0]

Just to be clear, are we able to turn the crankshaft all the way around twice freely with the plug pulled out? To see that it doesn't bind .?

Idler cog shud only spin backwards when installed.

Motor spins fine when decomp is depressed. He can kick it for days. I believe he said idler spins both ways right now.

So when the starter engages does it turn the engine over ok but it just won't start? Or will the starter not turn the engine over?

The starter isn't engaging anything right now. It spins free. If i had to guess I'd say whatever holds the shaft or gear onto the starter has sheared. The motor wouldn't turn over before because the gears were bound up. Now they're freewheeling and not doing anything. Listen to the sound it makes when he kickstarts it now. Sounds like a shaft spinning down from a high speed spin with no load on it.

[Goofy Footer 539]

I haven't touched the bike since the last time I posted picture updates. I'm currently writing this from memory as I have a test on Tuesday for which I should be studying as much as possible. I might be able to swing the bike up to senor Vacman's house tomorrow for a quick study break / non-starting WR moto-diagnosis sesh (thank you in advance for the help).

Here is what I recall:

1. Since I've had the bike, the electric start never turned the engine over.

2. I have always been able to kick the kickstarter through. Sometimes it was hard. When I would pull in the manual decompression lever on the handlebar it became easier. WRs should also have auto-decompression if you get the starter in the correct part of the stroke. Here is a video from before that shows what would happen when I attempted to kickstart the bike prior to opening the stator cover.

3. I pulled the stator cover, the stator appeared to be fine.

4. With the stator cover removed, I found that the starter motor would spin freely with no resistance on it.

Below is a picture to help label the gears / moving parts in our discussion and aid in my explanation:

A) is the output shaft on the starter motor and it spins freely when I hit the electric start. It stops spinning when I release the electric start. It can be manually rotated clockwise and counterclockwise.

B ) I'm not sure what B is named. From my recollection it only spins one way (and of course I don't recall which direction - I should remove the stator cover to verify which way it spins and to verify that everything is correctly aligned.)

C) Should be connected to the flywheel and B. Again, I believe this only spun one direction.

Note: Between A and B would be the Idler Gear. For the most part that seemed to rotate one way but I sorta feel that it had some play in it? Hard to describe and I will eventually try to get it on video. Might this play be the backwards "clutch" action which provides protection during a potential backfire? Not sure.

[PbdBlue 46]

It sounds like this bike is new to you. Does it by chance have an aftermarket cam or a YZ cam? Wondering if the auto decomp is working correctly. The '07 did not have a manual decomp from the factory so it must have been added by the previous owner which begs the question why? Has it always started this way since you got the bike?

[Goofy Footer 539]

It sounds like this bike is new to you. Does it by chance have an aftermarket cam or a YZ cam? Wondering if the auto decomp is working correctly. The '07 did not have a manual decomp from the factory so it must have been added by the previous owner which begs the question why? Has it always started this way since you got the bike?

Dammit you're right. I went and checked what I had been assuming was a manual decomp lever and it is the hotstart lever for the carb. I cannot explain why it feels (to me at least) easier to kick when the Hot Start lever is pressed - maybe it's a placebo effect.

I'm a bit frustrated with the bike. I broke a few of my own "rules" when buying a used bike and it's biting me some here. I may tinker with it when my testing is over but I admittedly want to throw in the towel or throw a safety line to a pro / more mechanically inclined moto friend.

Steps to solving my WR mystery would be

#1 remove stator cover and make sure all gears are in-line

#2 check valves (although unlikely, might as well)

#3 check to make sure it's a WR exhaust? cam

#4 new spark plug (why not)

#5 check ohms

#6 recheck BD kit wiring / switch (especially the kill & grounds)

Thank you for your continued help / questions!

[Goofy Footer 539]

The idler/torque limiter gear is a slip arrangement that prevents damaging the flywheel key in the event of a backfire when starting. The 03 wr's didn't have it and sheared crank keys. The big gear on the back of the flywheel is mounted to a one way sprag. When you kick start the flywheel should not turn the starter motor. Could be the sprag failed though they usually fail by slipping in either direction. If you remove the idler/torque limiter is it still hard to kick? If so I would pull the valve cover and have a look. Could be the auto-decomp mechanism is messed up. If you pull the plug does it turn over easily?

Could a Torque Limiter fail? (#4 in the service manual below).

VacMan came over for a bit today and we confirned that the stator appeared in good shape visually and that everything inside the cover was re-assembled correctly.

The starter motor spins but still isn't engaging the Idle Gear (#8) & Starter Clutch Drive Gear (#15). On the surface it appears the Torque Limiter (#4) may not be functioning / transferring power.

I Might be able to put the Torque Limiter from my 2005 into the 2007 and see if it works. A used 2007 Torque Limiter (#4) from eBay is $27 shipped.

Also, I'll try kickstarting it without the Torque Limiter.

[Goofy Footer 539]

Also, I'll try kickstarting it without the Torque Limiter.

I removed the Torque Limiter (#4) and kicked the bike over a few times after draining the carb and refilling it.

The whining sound from previous was gone and the picked sounded normal while kicking.

6-8 or so kicks later and it fired up!

The bike also seems to be easier to kick - no apparent binding/catching in the kicking stroke.

[PbdBlue 46]

I think you may have a bad one way sprague. It's on the back of the flywheel and is supposed to allow the starter to drive the crankshaft but once running freewheel. Removing the torque limiter just intereupted the path from the starter to the crank. The Torque limiter is designed to break free if the force exceeds a certain amount. It was added in the 2004 - onwards models to cure a crankshaft key shearing issue caused when the motor backfired during startup. The big gear on the back of the flywheel should turn freely in one direction and not the other with the torque limiter removed. It's a common failure. It's item 7 in this drawing:

[Vacman 0]

We could turn the motor with that gear one direction and it would rotate the crank, the other direction freewheeled iirc. I think the smoking gun is the fact that even when assembled correctly the starter didn't spin anything when the button was depressed. It's as though the teeth weren't engaging the torque limiter at all, or more likely the torque limiter was engaged to the starter but the bottom gear didn't engage the flywheel.