Highest compression ratio

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'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

I'll stay the same bore and stroke, just wanted to raise the compression ratio

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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