TaoTao ATM50 idle fluctuates and stalls
 

Hi guys,

My scooter has fluctuating idle, especially when the engine is cold - even stalls when the RPMs go all the way down. When the engine is not completely hot yet, the engine stalls when decelerating. Sometimes when trying to rev the engine when it's cold, turning the gas handle actually kills the engine. After it stalls, I'm not able to restart the engine for a while. Turning the ignition off and on helps.
Under open throttle traveling, the scooter develops top speed (30mph) so the powertrain works fine overall. When warmed up completely (normal operating temperature for an air-cooled engine), the fluctuation becomes tolerable, it no longer stalls.

So far I ensured that vacuum hoses do not leak and adjusted the valve gaps, but that yielded no significant improvement.

Please help!

Is this a newer model with tamper-resistant carb bowl fasteners?

http://www.youtube.com/watch?v=MLpkf2LINzo
http://www.youtube.com/watch?v=rbH9yp2kwM8