Rebuilding one of my 2002 Yamaha GP800R's. Ski Was running slower (55 MPH) than usual last season till it crapped out completly the other day. I found both power valves broken off at the base of the stem. Cyl #1 valve base was completely gone (chopped up and thrown out exhaust) and looked like it happened a while ago (slower speed problem ?). Cyl #2 valve base jammed into cylinder/piston/rings causing the breakdown (compression was 50 lbs). Pins were intact and have not loosened. Is power valve breakage common, or do I have an underlying problem ? See pic attached
