I queried Lynn Osborn, who ran UAV, the company that made the Bully 1.2, about the low speed needle issue and here are his comments:

Hi Tom,

Yes, the stock Webra lowspeed needles had to be modified. I found inconsistencies on length and taper from the factory. I built a jig that allowed me to shorten the needles to a standard length and steepen the taper. I don't have the jig anymore. It sounds like you might have gotten a unmodified needle. You might try to grind off about .020" from the end of the needle, round the edge with 600 grit and test run the engine. Keep shortening until you get back your highspeed RPM. I found the needles varied from .005" to .085" too long.

Take care,
Lynn