yz400 freak

Recently my clutch started acting all weird, i was riding it just like always (med-hard riding) on a local track when i started hearing a ticking noise... later when i took the bike to get checked out i found that peices of my clutch rings were flopping around in the basket...odd huh? i also found that my cam chain was off timing, and also thrashed after being fixed it seemed to run fine, but now i have noticed something odd. whenever i ride hard for mabey....20-30 minutes, the clutch seems to bind or sumthing. this only happens when going from a dead stop. it makes a slipping sound and tries to die on me unless i give it enough juice and a good amount of clutch feathering. WILL SOMEONE HELP ME???? any help on this matter would be greatly appriciated...