I have a 98 polaris Scrambler Sport. I recently had HPD bore out the cylinder .80 over. I replaced the piston, rings and wrist pin and gaskets with the Wisco forged steel pieces. I put everything in according to the instruction manual (Brother in law is a mechanic and did most of the work) Everything was coated in 2 strock oil and meticullasily cleaned. I started the quad up and let it run for 15 mins, and then road it around the neighborhood at normal acceleration, with lots of stop and go. Within 10 mins I heard a rapping sound from the piston. I have not yet taken it back apart. Any ideas what it could be? [img]i/expressions/face-icon-small-confused.gif[/img]

 

Did you check the ring end gap after re-assembly?? VERY IMPORTANT. I would say that is the problem or maybe the rings were installed incorrectly and may have broken.

 

Hate to sound stupid, but, What is the ring end gap?

 

The bigger you go on the bore the more clearance you have to get to keep it from siezing. Wiseco pistons also need more clearance than the OEM. A piston rattle is common after boring and should be heard. Now a real loud noise is not common, but a rattle will be. Almost enough to bother you. My big bore had 4&1/2 clearance and made a lot of noise. Ring gap should be in the .015 area.Bubba

 

Do you think this would effect a .080 bore? Will the noise subside?