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Highest compression ratio

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I've got a pretty well C4MX setup 2010 

 

Procircuit cam and valvetrain with flat valve

Yoshimura full system, twin air filter with removed backfire screen and a remap ECM

 

But the ported cylinder head was originally build to run with higher compression ratio than stock, so for now I run OEM piston with 91 octane gaz. 

 

 

How much I can go in compression ratio with 91 pump gaz

 

how much if I find 94 octane ?

 

Some here get good result with SMP octane booster, what do you think about this ?

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I've got a pretty well C4MX setup 2010 

 

Procircuit cam and valvetrain with flat valve

Yoshimura full system, twin air filter with removed backfire screen and a remap ECM

 

But the ported cylinder head was originally build to run with higher compression ratio than stock, so for now I run OEM piston with 91 octane gaz. 

 

 

How much I can go in compression ratio with 91 pump gaz

 

how much if I find 94 octane ?

 

Some here get good result with SMP octane booster, what do you think about this ?

i think the highest compression ratio should be fine on 91 octane, that being said it shouldnt depend if ou bore it or leave the piston the same size

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I run the JE 13.8:1 piston ratio (part # 291516) in my sons 2010 crf250r practice bike with 91 octane with out any problems.The bike currently has 319hrs on it.I normally try to change the pistons every 80hrs.

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