higher compression

[mjc597]

this winter i plan on rebuilding my motor.. i want to go with more compression but i still want to run pump gas.. i was wondering what's the highest i could go and still run pump gas?

[loons]

You can go to 12.5-1 and still run on pump gas. Depending on elevation you ride at you may be able to get away with 100 octane at 13-1. I'd stick with 12.5-1 though.

[redrider91]

i myself wouldnt run that high with pump gas cause my dad tried runnin 91 with a 11.5:1 in his 400 plus added octane booster and was having the gasses come out the head gasket.

[d3ktrix]

Originally posted by redrider91
i myself wouldnt run that high with pump gas cause my dad tried runnin 91 with a 11.5:1 in his 400 plus added octane booster and was having the gasses come out the head gasket.

The 450r can normally handle higher comp then the 400ex.

Originally posted by d3ktrix
The 450r can normally handle higher comp then the 400ex.

yeap there isnt a magic number for every motor for running pump gas. there are so many variables. liquid cooled can run a higher compression on pump gas than air cooled can. 11:1 400ex piston is usually the limit on 93. the 450r is 12:1 from the factory