MOPED ARMY

sounds like the carb slides are not coming back down

to the rest or idle position.

make sure the slides are in correctly.

cutaway toward the air filter.

also, check the springs .

if they are sacked out then stretch them out alittle.

make them alittle longer

Nope, probly not an air leak. My 250 does basically the same thing. Start it, idles at 1500 where I have it set. After a couple of minutes of warming up itll amble up to 2500rpm idle. Put any draw on the electrical system, be it brake light, lights, horn, whatever, and it idles back down to 1500 and stays there as long as the lights are on or there's some other draw on the system.

My RD is running the OMP regulator/rectifier, so I think you can eliminate your [presumably] stock ones as a cause. Honestly I haven't really tried to solve mine yet, I'm still working out some minor carb issues which are more important at the moment. If you do figure it out, please let me know.