how do i know its a big bore

[cummins99]

i have a 03 polaris 800 mod and i need a new piston how do i know its a big bore what is the size of it if any one knows it would help a lot thanks

 

[BB454]

800

Bore should measure 85mm for stock

 

[cummins99]

thanks a lot for the info it helpt a lot but i got more problems my motor got all ****t up my oilers whent out and now im sending it to a shop