Try making the idle ckt just a tad richer. Turn out the fuel screw 1/4 turn.
Check for any grit in the slide area ( the whole thing for that matter ) of the carb
Check the bike for air leaks, ie... head gaskets and carb boots.
Make sure the spark plug is tight
Just a few suggestions
check oring on mixture screw first, if flat replace it. QUOTE]
This is what it is. Bingo. Actually the o-ring is missing completely. IDK. I've just restored it after buying it and, though I cleaned out the carb, I never had the pilot screw all the way out. All I did was set it to 2 turns out. Never thought about the o-ring or checking it.
That oring did the trick...crazy how big of a difference this had on how the bike runs.