Bike stalling and missfiring when hot

[zippor25]

Ive been having problems with my bike missfiring and stalling. It would start fine and idle but when I get out in the woods after about 10 minutes it would start backfiring and miss firing and then would stall and not restart. I took it to yamaha and they said it was a bad ignition coil so I bought a new one and replaced it. It started right up and I rode it around my neighborhood for a bit and it ran fine. I went out Saturday to the woods, bike started 3rd kick and off I went. First 10 minutes or so everything was fine then I went through a tight wooded area and when coming out it started missing again. I rode to the truck and it stalled and I couldnt get it started again. I checked radiator fluid and it was about half empty. It seems to only start riding rough after the bike gets really hot. Someone said it could be my stator?!?! He said that when they get hot sometimes they start to fail. Any info please help I have been 2 months now without a full day of riding and I just dont know what to do!!

[zippor25]

had valves checked and they were way out of spec so they had to be shimmed and still nothing. Had a leak down test and found that I have 100% leak at the intake valve so now I need a total valve replacement!!!!!

[zippor25]

Should i just go ahead and put in a fresh top end while Im in there or no???