Rotax 670cc big bore

[KORE]

Not sure how often this has come up but the search but isnt workin so,, i need to know anything and everything bout the 670 big bore. Here is what i do know.. Im running a 95' 670 bottom end, burnt out top end and a 440 head. Id like to rebore the sleeves and go with a larger piston 83mm, im not sure if i should use a wiseco or the seadoo pro-x/sudco, what is a reliable comp ratio for premium pump gas, it will be going in a mountain sled to so keeping that in mind exhaust and jetting need to be addressed. short rv cover is on and 44mm mikunis will feed the fuel.