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Hey to all, I am looking at, thinking about a "Big Bore" upgrade. The question and I cannot seem to find on the internet is the head gasket thickness on any of the kits listed. Harley 114 is 11.0-1 compression as is the 117/124 at Fuel Moto. The reason for the question is I might want to lower the compression a .25/quarter point, though of engine reliability and pump gas. thanks for any guidance. CSM-H
 

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The better the combustion chamber and piston shape are, and more efficient the intake and exhaust valve tracts are, the higher compression you can run on the same fuel without issues. There is not an even comparison between the twin cam motors and the M8's.
 

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The stock M8 cranks 225psi. When duration (later intake close) is added there is room for higher compression ratio. Use the recommended CR for the cam used.
 
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