As Doug & Tom said: proper tuning is a essential 1st step.

Also:
[1] make sure the bike is breathing OK. Is your air filter clean?
[2] check the vents on the gas cap aren't blocked. Will it idle with the gas cap off?

Tierney - aside from those 2 hints:
Is your battery in good condition and holding a charge at 6.3V+?
Have you tested the condenser?
Is your air screw set near spec?

Good luck you guys!

- Dan