what kind of air filter do you have?
When you get moving, can you max it out?
If so what does your plug look like?
double check leaks, do it again, then again.
make sure your timing is not too advanced or retarded.
Your main jet does influence your idle some, but the idle jet could be a bigger problem.
Also (if you are new to phbgs)...check the wiki, it has a picture of what I'm talking about, and a relevant step by step walk through.
Your main jet isn't really used until 1/4 throttle (or later).
Anything below that is the idle jet.
If you have solved all other problems, and everything is in check, you might need to downjet your idle jet.
Note: I've built more bikes than I can count and seldom do I have to change the idle jet, but everything is different.