Thanks for schooling me on this, I had no clue about this subject! My buddy had his '09 RZR S rebuilt and replated, and had trouble with it peeling off. He had to send it back to have it replated, so I had doubts about it, but some of his problems could have been self-inflicted (running low in oil, engine underwater, etc, etc).

 

interesting the upper crank case in half the 09's 10,11,12 850 polaris is listed as iron lined.
but the pistons are not shown in oversize's

 

Got some more questions. I helped my buddy take the topend off of his '06 RM125 dirtbike. The piston and rings are shot, and the nickisil has a minor scratch in it that you can barely feel, but big enough that it needs attention. Can the cylinder coating be honed, or just recoated and not bored, or does it have to be bored and recoated?

 

Only time i honed a nikasil cylinder was when installing a new piston. It wasn't actually honing,just "breaking the glaze" so the rings would have a clean cylinder to seat. Only other time was if the cylinder had some seized aluminum from the piston and I would use some muratic acid on a q-tip to lightly eat away the aluminum ,then lightly hone. If you can feel the scratch,then best to have it replated! Basically all they do is hone the cylinder down and replate it to oem spec size. OPT

 

OK thanks. I took the cylinder by the machine shop and they advised to have it bored and replated. The scratch is minor, and they said it would probably run fine with minor compression loss, but to be on the safe side it's best to replate it.

I think the lesson to be learned here is to rebuild a nikasil-ed cylinder before it gets to this point. A new piston/rings (or just rings) and a gasket kit are a lot cheaper than having to replate it every time because you waited until it blew up!