My junker Quad that I've been working on for a couple years as time permits is at the reassembly stage after getting valves done. I've discovered the rings are frozen in the piston after I pulled the cylinder off to replace the base gasket.

Much to my surprise, the bore size does not line up with parts offerings. My piston is 71.5 mm and the cylinder at the top is 71.7 and bottom is 71.8. Stock is only 66 mm.

I can't imagine some went 5 mm oversize on this. Is that the only conclusion? Where can I find replacement rings or piston,ring combo that large?

 

If you have the 230,even Wiseco only offers pistons up to 2mm over size,68mm. Don't know what some one has done,either changed out cylinders from another machine or resleeved this cyclinder. What size does it say on the cylinder base?