Quote Originally Posted by barnone View Post
Gardo,
Are you saying that your engine has higher compression for some unknown reason? What compression ratio is Weaver getting when testing your engine? How is he testing your engine? Is your engine badly carboned up from running too rich?
I believe what Gardo is referring to is the compression in the cylinder not the compression ratio. The compression ratio on the 167FMM-M is 9-2.1 and will run fine with 87 grade Petrol. If the head is milled .025" it will raise it to 10.5, if there is enough clearance and it is milled .050" it will bump it up 2 full points. Anything above 10.5 and you should run 93 Octane Petrol. At that point you may also want to invest in a variable CDI one with a potentiometer so you can adjust the spark curve if need be to prevent the dreaded sound of engine knock