[Eagledriver]

This area of the case is the most difficult IMO. I've seen "tips" to use a bigger o-ring here on some engines. That tip caused me problems. The bigger o-ring pinched into the case halves and I had to do it over again with the proper ring. Another problem I've had was using silicon grease on the ring. Some of the grease got between the case halves and displaced the case sealant, causing a leak. I still use silicon grease there but keep it away from the part of the o-ring that is near the case seam. Watch this area as you mate the case halves to be sure the o-ring doesn't pinch out.

-Andy