2.00mm over bore, 21cc dome safe with pump gas???

[MX450]

My cylinder is bored to 68.00, 2mm over std, its also ported and polished. right now ive got a 19cc dome (cool head) and im running 100 octane race gas, i really dont have the money to keep buying it will a 21cc dome be safe with pump gas? Ive also got a stock trx gasket.

[Dave83]

That setup should get you below 190psi.Safest way is to do a compression test after its all together.

[MX450]

so anything above 190psi requires race gas?

[Dave83]

Thats the # most consider the max for pump gas.Detanation is hard on the motor,top and bottom ends both.When you lower the compression,youre gonna lose a little "pull" off the bottom,but gain some rev on top.