they all cook if jetted too lean , or get a lean mix from a leak on the intake or even a hole in the filter, or if timed too far advanced can cause pinging which can lead to premature ejactulation , spanish bikes need more "setting up " than jap bikes i feel, , it also seems different brand pistons withstand different levels of abuse , like i had a wiesco blow the top off for no apparent reason (pursang ) yet the mahle piston seems ok at the same settings , more suck i guess , but it,s mainly in the set up , so if it starts pinging stop the bike