Motorcycle Repair: CX500 runs rough after warm-up, air fuel mixture, main bearing

Question
I'm working on a 1979 CX500 that hasn't ran since 1995.  Step one was pulling the carbs apart, cleaning them, reinstalling, then same with the fouled plugs.  Inspected and cleaned air cleaner as well.  Noted some oil in the bottom of the airbox but haven't pulled it out yet.  Due to a leaking petcock (on order) I have a CM250 tank on it for fuel right now.  I've started it and it ran just fine, until it warmed up.  There is alot of racket coming from the engine (or possibly the cooling fan although I did not see any cracks).  After warming up, attempts to accelerate end up in alot of backfiring and then stalling.  It'll start and run again if I play with the throttle, but lacks any power at all.  I plan on pulling the carbs again tomorrow to check the mixture screws/springs/seals.  Any advice would be greatly appreciated regarding both the fuel and/or engine noise.  Could valve adjustment be causing both?  Haven't checked clearances yet.
Thanks,
Paul

Answer
Sorry it taken so long Paul, my wireless router quit working last week.

The poor running is probably an overly rich air fuel mixture.  I'd guess the float levels are too high making it run rich. A warm engine needs a lot less fuel then when the engine is cold.  

The source of the noise depends on what kind of noise you are hearing. If it a tapping sound, it's probably a loose valve.  If it sounds like loose marbles in a can, it could be the cam chain adjustment and if it's a knocking noise it could be a rod or main bearing.

Regards
Rich