Woodruff Key Seared, the bike is dead.

Okay, I finally found some spare time to get in there.

My suspicion was that it was flywheel related, given the history of these engines and all. I also could engage the starter and it just free spun, so I knew something was up. The engine still had compression as well, pointing me further towards something with the flywheel.

Then I found this person with a similiar experience on another forum:


Turns out, my situation is literally identical. I took the engine cover off, pulled it out, and the fly wheel was there and all... but I grabed it and went to spin it and it just free spun. Then I went to undo the bolt holding the wheel on... and it was finger loose.

So, obviously it wasn't torqued right or came loose over time, rattled loose enough to sheer the woodruff key (holds the flywheel to the crank shaft) and that was that... boom bang engine stops running.

I ordered up a new woodruff key and a new gasket. I'll pick up some oil when the times is right, slap it all together... and I should have a working bike again.

What is a woodruff key?

It's a small little piece of metal, shaped in a semi circle fashion with a full flat edge. It fits into the end of the crank shaft, and is used to properly mount the flywheel and keep it's orientation.

End Result:

Replaced woodruff key. Fired up. ran like shit. Started overheating pretty notably (could feel heat). Oil was leaking from sidecase... all in all this was the death sentence for this bike. I'd gotten a lot of fun mechanical work out of it / wasted a bunch of time and money. The bike was surely done for.