Ok here is what i ment by lapping the head and block.
This is quoted from a guy i know on another forum heres the link.
http://www.diygokarts.com/vb/showthread.php?t=5773&highlight=lapping+headI did this ONCE to a 2.5 hp engine my freind had because he didnt have a gasket and he had a stuck valve.
"don't work with anything 4 cycle anymore (for many reasons), but here's what I do.
I eliminate head gasket completely and lap head and block using 320 grit Clover Silicon Carbide Grease grinding compound.
Only needs to be lapped until both surfaces (complete circumferences) show a uniform gray color. Minimal amount of material is removed and is controllable. All that is being done here is increasing flatness and has a two fold purpose:
1.) Eliminating the need for a gasket
2.) Creating an absolutely flat surface for which the flange sealant can properly do its job.
Takes about an hour or so for both surfaces and is (in my case) equivalent to milling .040" total or the thickness of original gasket. Reason for lapping is that surfaces are not absolutely flat...hence the need for gasketing. Lapping is not part of the manufacturing process as it is not cost effective (time and labor).
I've done it to all my 2 cycle power plants. Gain is probably in the .5 hp range or more.
A flange sealant must be used, such as Permatex Super "300", in place of gasket and torqued to max factory spec. If surfaces are not lapped, sealants will not hold and will blow through in short order.
Been there, done that.
Hylomar can be substituted for the Super "300".
Clearances should be checked with modeling clay before final re-assembly.
Don't want anything clobbering something else. "
