more starter info

Okay guys here's the scoop:

Picked up my wr450 from the dealer tonight all fixed..I hope! After lots of discussion with the mechanics at my dealer and feedback from everyone in this forum, here is my take on it. The bike must have backfired while being started by the button. The throttle was probably opened a bit because of the lean jetting (stock never been touched). I was cracking the throttle a bit because that was what seemed to work best. The manual says keep your hand off the throttle while starting with the button or kick starter for a reason. If the throttle is open just a little bit it moves the throttle position switch telling the ECU(black box)to advance the timing. This could cause a backfire, and if the stars are aligned wrong send the energy backwards thru the start mechanism and shear the flywheel key and backing the nut off!! Don't know if the ECU has any provisions for not advancing the timing until the engine is turning a specific RPM, but that would reduce the chances of this happening. The correct jetting will also help as well. I rode it tonight for the first time without the throttle stop, and it now feels real lean. I got an xtra flywheel key from the dealer-just in case-and it is not very big (2.5mm wide 10mm long maybe). So....dooon't touch the throttle when you start it!!! I just hope I can let anybody that doesn't understand any of this technical stuff ride my bike and not worry if they're going to break it!! It still feels great and I have no regrets...I know Yamaha will make it right, and my dealer POWERHOUSE will stand behind it as well. Can't wait to log some miles on it and get it dialed for me. Waiting on SCOTT'S to build a mount for my stabilizer now. I'll post again when I know more. To all who don't have theirs'll be bitchin


I must apologise for attacking you when you were asking a valid question not a very nice welcome

But as you spend more time here you will see it looked like a typical troll with no profile etc

In future I will not be so hasty to boot down a troll

Patience my butt, I have been waiting 6 months. Just reading the stories from you guys I am ready to fly to the USA, hunt the right dealer down (gun point if necessary), bring the bike back to New Zealand and finally, finally, Patience wont be an issue.

The dealers here are still saying its anywhere between end of Feb and mid March. Guess which one I am believing ....

sigh ......

Mine is due 10Feb

we get the same spec bikes as you guys do so you may be lucky as our bikes will be on the same production run.

roons, We greatly appreciate your input. Keep it coming. I am really having seconds thoughts about the WR450. I can't have a woods bike that I have to treat like a raw egg. Where I ride I am often 15 miles from the nearest paved road...

Thanks for the update.

Ok guys here is my take. You may think this is highly subjective and you may not agree with me but thats ok.

My bike suffered a sheared woodruff key and in the investigation and repair here is my conclusion.

First off this failure is in no way related to, or any function of ,the starting system. Second it is not specifically related to a engine backfire.Yes thanks to our friends over at the EPA this bike is too lean and probably will backfire. A backfire like any heavy stress (stall at speed, full power etc.) could cause damage somewhere in the motor.Particularly if fasteners where not torqued to spec. or maybe even completely loose. In my case I stalled the bike after aprox. 40 trouble free miles and the insufficent torque on the magneto nut caused the flywheel to shift and sheared the woodruff key.Bingo no go!!

And the fact that Yamaha has changed the spec. in the manual tells me that we are on the right track. By the way my dealer was extremely concerned and very fast in repairing ( 2 hours) my bike at no charge to me. I now plan on riding my bike and never looking back. I may check the torque from time but don't expect any further problems. If there is my dealer has promised to step forward.

So guys check your nuts and enjoy your new toys.

Peace out SMD :)


Do you know what torque spec the dealer used on the rotor nut when they repaired it?

The key seems small compaired to other bikes I have owned.

Maybe with the heaver flywheel on the Wr. it should have been a little wider ?

Alot of husky riders used to lap the flywheel onto the crank to provide a better surface contact.

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