2003 WR450- yet another casualty. No start

This time, the bike won't start. It acted as if it fouled a plug, after riding it about 8 minutes. The battery was dead before I kicked it to life. I have put 2 new plugs in it and all it does is that "fouled plug" backfire (after about 5 kicks). I have put the battery on charge and it is now good to go. I haven't done any other troubleshooting, as of yet, as it just failed over the weekend. The bike won't start when kicked, or the magic button is pressed. I am following my normal start drill. As the WR450 Yamaha manual has limited troubleshooting hints, any advise would help. Thanks. :)

Hmmm... sounds kinda like ignition. Have you tried turning it over with the plug grounded to the outside of the head (gas OFF) to look for spark?

That would be my next step.

Sounds like you may have sheared the infamous woodruff key. :) Did you have any backfires prior to this happening?


I just came in from the garage. I removed the plug, grounded it to the head, and cranked it over. LOTS of sparks. I have had a failure of the starter clutch gear before and have had the flywheel off to replace it. I installed the new woodruff key and have loctited it.

Does this sound like a woodruff key failure to anyone? Are these symptoms anything that anyone else experienced when there's failed?

This is such crap that these failures have happened to the 2003 WR owners.

Any more suggestions?

If you are getting plenty of spark and have no fuel delivery problems then my guess would be the timing is off which is what would happen with the sheared key.

Anyone that has experienced the woodruff failure have any input?


it definately sheared the key. :)

does it turn over with e-start? if so doubt it's the woodruff key. when i sheared my key, e-start would only make a whizzing sound but not turn over the engine.

Engine DOES turn over with the e-start. Does this sound like the woodruff failure?

Sounds like it to me. I have a buddy that has had his fail 2 times while I was riding with him. First time it just would spin fast. 2nd time it would turn the engine over. You need to pull the cover to find out for sure.

the key can be sheared and still turn the motor.

the key can be sheared and still turn the motor

Thats what I was trying to say, that I have seen it still turn the motor and seen it not. I would bet that this is a case of a sheared key.

Yet another failed Key. Yamaha will go done in history for their shoddy engineering and arrogance. They sent me a survey last week. Can you believe it? Would I buy another Yamaha? Only if Honda, Suzuki, KTM and Kawasaki were all out of business....

Check the key is no big deal .Once you get it home.My dealer new i was coming in to get a new key.My mates went in and told him that yamahas are [@#$%&*!],especially when we had to push it 7 ks on a stinking hot day.Its funny he had already rang yamaha and had the parts sitting there for me when i went in to chew his ear.No charge .He supplied the update 04 parts at cost also.Now thats a great dealer.His help made me change my mind about buying another brand after 6n yamahas.If it happens again tho.?

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