kz440 makes weird noises and exhaust pops

I have an 81 kz440LTD that I bought a few months back. when she first ran she had a real bad clunking noise that feels almost like transmission or something (only speculating). A buddy and I disassembled the carburetors and cleaned them and replaced the air fuel mixture screws. We didnt mess with any of the jets. We also coated the gas tank but now theres some crap in it which could be causing the main problem: the bike doesn't like to idle and when it does the RPMs are inconsistent. they go up and down randomly. Also there is a clunking noise still at low RPMs. as well, when shifting down with medium RPM the exhaust pops. Anyone have any ideas where to start looking for problems?

delta 224 wrote: ... We also coated the gas tank but now theres some crap in it which could be causing the main problem: the bike doesn't like to idle and when it does the RPMs are inconsistent. they go up and down randomly. ....

Liner crap? If you didn't line the tank properly, then you may have to start over w that.

Does the bike have the stock airbox or pod filters?

Stock air box

Popping on decel could be unburnt fuel (fuel not atomizing properly). Something might be up with the fuel mixture screws or maybe the carb is still dirty. If it were me:

Re-Clean carbs
add inline filter
double-check carb holders

Good Luck!