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1972 gt750 cylinder head machining
jaxjake22 said 2008-05-21 06:06
if i machine 1mm of of the cylinder head the service manual claims that i should reach a compression of 150-160 psi. so i´m guessing that i will need to run premium fuel 92 octane? will i need to increase main jet size? i am trying to increase compression, i only have about 105 psi on all 3 and i was hearing what i thought was a top engine noise like piston slap when cold but when i removed the head i noticed all pistons were covered with carbon and i did not notice abnormal cylinder wear. so i´m lead to believe that the noise i was hearing was detonation. i cleaned off the carbon and would like to raise combustion temp to keep carbon off and run a little cleaner. i want to keep the engine reliable and somwhat stock. i know these were low compression engines. the service manual also claims that they are reliable up to 3mm machined off of the head but if 1mm raises compression to 150-160 psi, what will 3mm be? i suppose i would have to run race fuel and advance ignition timming? i just don´t want to destroy the engine from a slight modification. the bike is in pretty good shape and i inherited it from my father after it sat for about 18 years. i just would like to improve performance a little more knowing that i can raise compression fairly easy, but with what other modification will need to be done?