I'm continuing my quest in a new thread now that I have a more specific question. Old thread is here (http://www.hobbytalk.com/bbs1/showthread.php?t=133561)

I got a new flywheel key as the old turned out to be broken. The new one broke after about three pulls and one ignition...

The new key looks like a dud though. The sheared surface looks dimpled as if the metal had bubbles in it. The old one looked solid and the sheared surface is smooth.

Could I have been so unlucky that I got a bad new key or is a second broken key a sign on some other problem? If I remove the spark plug and turn the flywheel, it seems to run smooth.

/Ola

Success!

I got a tip that I probably didn't fasten the nut enough and that's why the new key sheared. So, I got me a decent torque wrench and cleaned the surfaces properly before assembling this time. No problems at all and the engine started on the second pull :)

yeah, that nut has to be torqued down to a certain spec, so not to shear the key.