1. The factory service manual says to change the piston and rings every 15 hours-I realize that is based on a racing schedule, but I dont race, and that seems a little excessive. There is nothing in the manual about checking the compression; do you know what the compression should be? Not trying to be cheap, just dont like to fix things when they aint broke. I normally ride a 650R, so, well you know..... 2. I replaced the factory piston after about 30 hours-there was virtually no wear. Put a Wiseco kit in, ran exactly the same. It has always been hard to start cold. Put in the R & D powerbowl, did not have any effect on starting. Dropped the main jet to a 172 as Charlie C suggested some time ago, and that improved the cold starting dramatically. I am approaching 40 hours on the Wiseco-the bike runs great, doesnt go through oil. So the question is, would you guys just replace it to be safe?