I recently bought a CT racing built 440ex engie and it has a 13.5:1 copression ratio which requires race gas, i ride alot and cannot afford race gas, now my question is....what i the best piston/compression ratio for me? i dont want to run race gas, just premium with octane booster and i ride alot so i dont want to take all he reliability out of my engine or have to upgrade the rod.

 

friend if your over 4ooo above sea level octane boost will work with your 13:1 if your below that and want to scrap the 114 octane gas go to 11:1 with octane boost will be fine.

 

i would not recommend running octane booster. i would just buy a 10.8:1 ross or je piston and maybe even lower than that if your running a 440 with the extra heat made. with much higher than that, you will want race fuel, not octane boost, heavy duty studs, stronger rod, etc. many of the octane boosts are more harmful than helpful. most have chemicals that are rough on valve seals. many others barely raise the octane of the fuel even though they say they do. you might get away with the 11:1 compression with pump gas but it might detonate at higher temps.

 

I agree^^ heat is an engine worst enemy, i wouldn't go any higher then 11:1 you really don't need a high compression piston..

 

I was thinking somewhere along the lines of a 11.5:1 ratio piston, would I be able to get away with this on 93 octane? it already has the HD studs, cam chain, valves, springs, etc...

 

i think the bike will run with 11.5:1, but not to its potential on 93. now, is that a true 11.5 or a rated 11.5?

 

I dont know but heres my question: what is the higest copression piston i cold possibly get away with on 92 or 93 coctane pump gas?

 

i would only run a 10.8:1 ross or je on pump gas if it was me. you won't notice a difference in power from a 10.8 to 11:1 anyways.