engine rebuild

I have a 2004 Sportsma 600 that I am doing a top end on. After inspecting the cylinder bore I found that it is 79.5mm instead of the 76.5mm standard. I am looking for oversized pistons however I cannot find any. Does anyone know I they sell them? Also I was looking to see if a 700 cylinder would...

I have a 99 Polaris explorer 2stroke bike. Was having trouble with water Pump seals on balancer shaft. So I replaced the balancer shaft, I got a Remanufactured one ,that had new shaft for seals to ride on. Looked really Good.seals were tight.went ahead and rebuilt whole bottom end while It was...