Oil on top of my domes around spark plugs on coolhead.

[252wheelieking]

Can anybody tell me, what causes oil to leak on top of my domes on coolhead around spark plugs? Its on both sides.

[AKheathen]

overtightening. it compresses the sealing ring on the plug so that it no longer has any "spring" in it and no longer seals. on the other hand, it can also streatch the threads. try brand new spark plugs and tighten them to spec.