13.5-1 piston on pump gas?

[GBC]

Will a 13.5-1 piston run on pump gas in my 2000 426?

[642MX]

Of course it will, but it may ping. If you hear it pinging then you need to blend some race fuel with pump fuel.

[GBC]

Well I dont want to run race fuel at all. I know we can run 13.5 pistons just fine on pump gas in the crf450 but I was wondering if the 426 can do it as well.

[grayracer513]

Under most circumstances, yes you can. Only if the engine is lugged hard at a lower rpm will it ping on reasonably good pump gas.

[whyzee426F]

...so how much actual benefit is there to running a 13.5:1 piston?

[642MX]

...so how much actual benefit is there to running a 13.5:1 piston?

Increased torque from idle to mid-range. They don't do much on the top end, but from the bottom thru the mid range they rip. I wouldn't rebuild my motor without one. ?