On a sportsman 500 non ho. But will be putting in an ho cam. How much can be milled off the head before you can't run pump gas? Or run into valve clearance issues. Will be using a wiseco standard compression piston. Basic reason for the mill is a cleanup since it needs the cam replaced, will be boring also. 5000 miles it's time for a bit of work.

 

I think compression wise you need to stay under 160? not sure....

 

Compression ratio is what dictates octane requirements from what I understand. As far as how much you can shave from the head, I couldn't tell you.

 

Don't mill that head for compression !

Problem 1 --> Cam timing gets thrown off .

Problem 2 --> Valves can tangle with piston .

Buy a hi compression wiseco piston .

 

Thanks guys. Now that we've got that answered. If this thing needs resurfacing, what would be acceptable there? A couple of thousandths for a cleanup? The owner said that it has gotten hot several times and would like to make sure the surface is true.