1998 Yamaha XL1200 ran perfect cut off during a turn?

I was riding my waverunner and I turned and all of a sudden it just putted out with my hand full throttle. I couldn't get it started again. So I swam it to the dock and after messing around and pushing the starter about 50 times it started back up again. It ran for about 10 minutes then did the same thing to me. Next morning I went out to start it and it started right up I ran it about 100 yards and it shut off again. Now it just won't even turn over. Battery is good and spark plugs are new, any suggestions????