Same issue for me. My 3rd just blew. Onto my fourth. Whats up with this?. Not every bike has the issue, as my mates 450f has had no probs. Any ideas why some are giving out?. It cant be the gaskets (bad batch etc), as it would have a wider impact. My mechanic has checked that everything is square, no sharp edges etc, and everything is torqed correctly. Even tried the silicon sealant to be sure. Still no fix. Its now a very expensive problem.....My last one blew in near freezing conditions in the rain, so im not sure that heat has anything to do with it. Has anyone in Australia had any luck getting Yamaha to provide a new gasket.?