What I would do:
Change the plug
Check for airleaks
Be sure that fuel is flowing in a THICK stream from the fuel valve (petcock)
Do check to see about the throttle opening and closing all the way.
Be sure that the air mix screw is out 1 full turn from closed and leave it.
Do you have a compression tester?
The stock pilot jet works well, but I ended up using a 17.5 instead of the stock 22.
A 145 main jet is about right where I live. Somewhere in that neighborhood...
Needle setting should be the last thing you tweak.
These setups when tuned rip monkey ass.