Trail side woodruff key replacement

has anybody replaced their woodruff key out on the trail ?

when the key shears.. is it possible to get the flywheel off , without a puller ? how much oil do you lose if you lay the bike on its side ? i'm thinking about carrying a spare key....just in case. :)

You may need a puller even though you sheared the key and spun the flywheel on the crank. My fear would be that you can not get a good seat from the damaged surfaces and then the new key will shear immediately on start up. May be worth carrying around for a while until you get some confidence in your bike. I have 1,023. miles on my WR450 and never touched the flywheel only checked the rotor nut for 50 ft.lbs of torque. It never was loose and never budged when I applied even 60 ft lbs. in the beginning when there was a typo in the manual. :)

let me see..... :) i'll need a puller.. something to clean up the galled crank and rotor with... a key..

a new gasket.. some oil.. a torque wrench..


Just keep putting miles on it and gain confidence knowing that there are many of us without a woodruff key failure. Most of the failures were cured with the Service Bulletin fix. I have got lucky on the flywheel taper tolerances fitting with my crank. To feel more confident you can; Lap the fit, Permanent Loctite, and Put your own tool steel key if that will make you feel better. Have you ever crashed and had a rad go on your bike 30 miles from the truck? The woodruff key is not as big a deal as other problems that can happen. You just can't carry a spare bike. Ride with buddies, tow strap, cell phone and you should be plenty safe. I love riding with an ATV or 2 in with a big group of bikes. They carry a lot of tools and emergency stuff. :)

Don't forget that Timing light :)

lets see, lapping, is putting a bunch of abrasive into a mechanical joint.

Machining is a very different process.

Lapping can be used to create a witness, be used as a reference or just be used to try to manipulate a surface harder than the parent material.

Creating a matching or locking taper is 100% different than rubbing some abrasive grit on an ID/OD relationship that was

not right in the first place. BTW, some abrasive grit could be the cure here.

After lapping, even after thorough cleaning, that abrasive is still inbedded in the parent structure.

'04 will have a larger OD on the rotor side.



A larger O.D. will just transfer the issue to the crank shaft and then we may have crank failures. Maybe the flywheel will be a tad lighter in 04. I doubt very much that Yamaha will make the crank a larger diameter for the WR only since the YZ450 out sells the WR and has no issues with the flywheels spining off. :)

A trailside fix could be done. I have a flywheel puller and it wouldn't be a big deal to do.

Beats walking.

Chances are, if the flywheel spins enough to sheer the woodruff key, the bind between the wheel and the shaft will not be enough to need a puller. In my experience, when the wheel spun (on old bikes) there was no need to use a puller. In an emergency, you may get away with laying the bike on it's side, remove the cover, remove the nut and flywheel, clean the shaft+flywheel,install new key, replace flywheel/nut, tighten the piss out of the nut. this may get you out of the woods. Last resort. This prcedure wasn't too uncommon on old bikes (euros), it's really a shame we should even have to CONSIDER it on a new Japenese bike. If my bike breaks on the trail, I will probably be doing the emrgency fix. I've already ordered a new key. I'll let you know how it works out. I'm hoping I won't have to find out.

Don't forget the Wild Turkey for the rebuild.

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