New 08 YZ450F Sheared Woodruff Key

Hi all,

I recently purchased another 08 YZ450F.I took it apart and regreased all linkage and steering. I installed a GYTR fuel screw and rejetted it . I ran it the other day and put .6hrs on the meter and it ran good. I went to start it today to warm it up and change the oil and it was a pain. It would backfire and just didn't seem like it was timed right. I took off the stator cover and removed the flywheel and the woodruff key was gone. The flywheel and crank look good. I drained the oil and looked all over for the pieces and couldn't find any thing. I have a GYTR oil drain bolt and a Moose Magnetic filter cover and neither had excessive metal on them. If it dropped into sump is it possible to be drawn into the pump? If it went into the tranny is it soft enough to be chewed up and spit out?

Thanks,

Chevelle

Most likely, it's stuck to the flywheel magnets somewhere. If it dropped off the shaft and did not stick to the flywheel or drop in a drain pan, the first place internally it could get to is the sump, by way of the port behind the flywheel. It's too big to go through the oil screen, but it could cause trouble with the trans. If it sheared, the parts would be jammed in their slots, and the crank and flywheel tapers would be galled badly.

did the previous owner take out his aftermarket flywheel before giving the bike to you thus forgetting to put the woodruff key in allowing the described problems to occur?

Just a thought.....

It wouldnt run with out it. The ignition timing would be crazy due to the slipping. I agree with gray, its probably stuck to the flywheel somewhere.

Thanks for the replies. I looked all over the flywheel and the stator and found no pieces. I flushed the pump area out and found no pieces. The crank area and flywheel slot both look good. It is very puzzling?:thumbsup: By the way this is a brand new bike with only .6hrs on it.

Thanks,

Chevelle

If you are sure it's not in the engine, just install one and go on with things. It may have been built without a key by mistake.

If you are sure it's not in the engine, just install one and go on with things. It may have been built without a key by mistake.

And it would possibly run for a while without a woodruf key if the timeing was set right and the flywheel tightend down. From the vibration of the engine if it did in fact make its way to the trans area there is the lower section of the case where the drain bolt goes and usually if anything makes its way to the trans it ends up there where it cant hurt anything (I cant remember how the casting looks from the ignition cover to the tranny). If it sheared off you would have found half of the key in the crank slot.

Thanks All, I think Gray may be on to something. That sure would make since as to why I can't find it and there appears to be no damage. I ordered a new one and will see hw it goes.

Thanks Again,

Chevelle

I have seen what a small piece of metal can do to a yammi, I replaced cases, cylinder, crank, piston, 2 tranny gears, and assorted bearings. I would split the cases and find the key. My friend spent a good chunk of change on parts. He was lucky, the bike stayed running and he was able to pull off the track (supercross style track). I know it is alot of work. Good luck.

E.

I ran it the other day and put .6hrs on the meter and it ran good. I went to start it today to warm it up and change the oil and it was a pain. It would backfire and just didn't seem like it was timed right.

If the bike only has .6 hours on it, I'd take it back to the dealer for inspection and/or service. A sheared woodruff key (or missing one) isn't exactly a wear and tear item. If the place your purchased the bike is a good dealer, they'll help you out with this.

Maybe when you removed the flywheel it landed on the garage floor.....and the problems you experienced were more jetting related?

As mentioned if the key sheared there would be "Witness marks" on the shaft where the flywheel spun to shear the key....And to answer your question can the key damage the tranny gears...Yes it can and most likely will if it's still in the motor....

Maybe when you removed the flywheel it landed on the garage floor.....and the problems you experienced were more jetting related?

I guess that could be possible...but I have never seen a fit that loose of a key

slot in the crank axle.....

Good News,

The owner of the dealership where I purchased my 450F called me wednesday evening to wish me merry christmas and say thanks for buying my 450F. He asked me how I liked it and if I had any issues. I told him about the flywheel key missing and he offered to fix it or if I wanted to do it myself he would send me the parts. He told me if I just wanted to replace the key and ride it that he would put the issue into the database for Yamaha and if issues arised afterwards because of it that Yamaha would warranty any damage and work needed and if not his dealership would. Rock River PowerSports in Jefferson, WI. has my bussiness from now on , even if they are 3hrs away.

Thanks for the Replys,

Chevelle

that is great news that they are going to stand behind the bike and they sound like a great dealer.

Hi All,

Just a quick follow up on my missing key. I finally got around to pulling the motor and tearing it down. I found no woodruff key hiding anywhere. I put the motor back together and it runs very good now that the timmng is correct. I called the dealership and talked to the owner and explained to him what I did and he said the issue was in the database and to just ride it and have fun. He said if issues arise later to just give him a call and they would take care of it. Man it's really strange for me to deal with a dealership that truly strives for customer satisfaction. I thought that was lost when profit and bottomline took over Corporate America.

Thanks for all the Advice,

Chevelle

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