[dubya.brooks]

New to me 420 and just took a look at the rear crankcase. This doesn't look like any diagram I've found online. The toothed "wheel" is spinning when the engine is running. What am I missing? There was an o-ring loose behind that toothed wheel as well.

 

[dubya.brooks]

Thanks everyone! It wasn't mentioned in the service manual I have. Now just deciding to either remove it and put on the original cover, or add the recoil.