LCGB Forums

I had a problem staring the GP, I had the timing set at 21deg, had a good spark etc but closest coming to starting was backfire. Thought I'd change the timing to 19deg, however after removing the flywheel found the attached damage, question is the keyway is ok on both crank and flywheel, would changing the woodruff key suffice?

Was it loose or was the key snapped and thats a new one?
Personally I would remove the key and get some valve grinding paste on it and lap it in. You will then have a dull ground area and get a better idea of how much area is damaged as it wont be dull.If they are ground and matched with a new key it should be OK. Also check that the new key is not too high or it will hold it off the taper and it could chatter.

same key, flywheel has only done around 10 miles since changing same.

Flywheel not seated correctly.Is it the correct one for your crank?
If so,as said,lap it in until its all dull grey,the check you key isnt to high.Maybe file it to make it not protrude as much.The key is only to put the flywheel in the correct position,its held on the taper.Make sure you torque it to the correct value too.

When I enlarged the pics on Photobucket, they look like grooves in the surfaces, not scratches.
From what I saw, the crank is scrap and will never lap in to a useable state.