I'm at 850 ft. Have an hmf full system, kn air filter on the grizz. The current carb settings are:
185 mikuni small round
dyno jet needle on 5th notch
4 turns out on the mixture screw. The problem is: on decelleration, i have some backfiring and popping throughout the carb sometimes. Do you think a mikuni 190 small round will solve it? Any ideas? Btw the plug is white indicating lean.

 

Backfiring on decelleration is caused by the piot being too small, not the main. just an FYI