ive heard a few horror stories about pro-x pistons, and about a thousand from vertex, the wiseco is the best hands down, magicracing.com carries complete kits that include piston/rings/wrist pin/gaskets
when you take the head off of the cylinder, in the top of the piston the size should be engraved, you may have to look hard and bust out a wire brush to klean the junk off, if it says STD. its the stock one, anything other than that, the size will be on there, for example .20, .40 etc
ive heard a few horror stories about pro-x pistons, and about a thousand from vertex, the wiseco is the best hands down, magicracing.com carries complete kits that include piston/rings/wrist pin/gaskets
I run Wiseco, they are the best out there in my opinion, pro-X had some terrrible mishaps in the past, just ask around if you arent sure tho, but id say Wiseco, i never had a prob with wiseco in my blaster
the mechanic at my old shop had like 2-3 pro-x pistons that crowned (top broke off) he said it was only those few over the kourse of like 6 years so not bad, but he was only going to use wiseco-prolite in my lt250r