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Sudden Death

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Hi fellas,

I've got an interesting one for you!

Went riding with my buddy on his 03 WR250. The bike was running fine and then all of a sudden just stopped. Since then it will not start. It will turn over fine with no bad noises or loss of compression.

Natrually I've pulled the plug and checked it. Checked for fuel supply, etc... no problems there! The bike is jetted perfectly also.

The bike will cough / backfire when you kick it over. It makes a woofing noise. So obviously there is spark.

The next interesting thing is that the starter motor stopped engaging properly... but only temporarily (it has previously never had any such problems). It sounded as if gears were not meshing and subsequently the engine would not turn.

At this stage I am thinking that perhaps the rotor has come loose, thus distorting / mis-timing the the ignition signal.

I am aware of some issues with the sheared woodruf key on 03 model WR450's. Is this a related problem? Is the rotor possibly just loose, in which case, will the key require replacement?

I will crack it open to have a look later this week (check rotor ignition markings), but would be interested to hear your thoughts prior to this.

Thanks

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03 wr250f's had the woodruff key problem also, they also have a problem with the rivets on the magneto or something. Open up the left side and you will more than likely find the culprit within the ignition. Good Luck and keep us posted.

OWENLO :thumbsup:

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if the motor will turn over, it has spark and backfires, your valve clearances should be checked. this process is very easy to do and takes lkess than an hour to check them. if you have an service manual for your bike follow the steps for checking your clearances and if they are out of spec use the chart provided to find the right sized shims. make sure your motor is at TDC when you are checking them and if you need to replace the shims and take the cams out put a piece of long wire around your cam chain to keep it from falling into the motor. also if you take the cams out be careful to not drop the clips into the motor also. if that happens you will either have to fish em out or take the left side case off and then find it. which is not fun because you also have to drain the oil to take the case off. Hope this helps you out and good luck!

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Thanks for the feedback guys.

I had thought about the valve clearances being a possibility, however I didn't think that this would force the bike to stop dead in its tracks. The bike is never difficult to start (first kick even when hot). I will however check them when I begin to pull it apart.

As for the riding conditions... we have only been riding in dry conditions.

Given that the starter motor played up at the exact same instant, I am almost certain that the rotor (or something in that region) has come unstuck. When I pull it apart I will check that the marks on the rotor align correctly when the piston is at TDC (along with cam alignment). I will also look for anything else suss.

I will definately keep you guys posted on this one. If anyone can elaborate on the woodruf key issue this would be appreciated. I have searched the WR450 forum, but their electric start configuration looks different to the WR250???

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I was buzzing down the road last week. I just put $800.00 in to my WR. I was in 5th gear and not revving high. The bike just died. There i was with my new tool kit and i was dumb and founded.

Turns out i had a short in the kill switch. It allowed the starter to work, just no start.

I brought it back to the shop and had to pay for 1.3 minutes labor. They just pulled out the kill switch and voila.

Hope this is your problem. This was my 4th kill switch. Now I use it as an anti theft device. Unplug it to ride and plug it in if i leave it in town.

Later

OT

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Well fellas,

I cracked the WR open the other night and sure enough.... yet another woodruff key failure. The flywheel nut was on really loose and the flywheel had subsequently come adrift and sheared the key.

Thanks for the responses. Looks like its not only the WR450's that have the problem.

Thanks again,

Bergermeister

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