Coming home from work today i noticed a rattling which sounds like its coming from the engine. When im riding it sounds like a loose pice of metal, sort of a buzzing sound...only noticable on acceleration. I revved it up several times in the driveway and it sounds like it could be a timing chain of some sort..or somethign similar? it definately sounds like its in the engine somewhere, maybe more toward the heads but the exhaust noise makes it hard to tell. It wasn't doing it before i stopped and filled my tank, then about 1/2 way home from there i noticed the noise. I'll take a closer listen tomorrow but untill then, any thoughts or suggestions on what i should listen for? ???