HELP!!!!!!!!!!!!! K&B .20 (.25) Head Problems

[cjorlando]

I have an older .20 sportster engine that I updated the cylinder and piston to a .25. Bought the parts through K&B, but now I am melting the o-ring that used to seal off the head. The head is still original to the engine so now I need to know if this also needs to be replaced? If so then with what part number? Will it require any other parts ie gaskets, shims etc? Plane is sitting still and not happy about that in the least bit since the hop up kit did not mention anything about swapping out the head. Please help me out so that the remainder of this summer is not wasted like the first part!!!!!!!!!!!!!!!!!!!!!!!

Chris

[MECOA]

The reason the o-ring keeps blowing is because of the .25 conversion. The o-ring in was made for the early .20 only.

Buy a new head part number 11-5601