Hi, I'am new here, and hoping to find out solutions about my two quads.
First: It 200 cc 4-stroke engine, with original 200cc carburetor.
Problem is that, starting on cold engine getting stalled, don't matter spinning idle screw, only works pushing throttle so i get engine working, second problem is that engine works fine only in low RPM, medium-high engine "shake" and getting stalled, also when engine is cold and a bit getting hotter in idle RPM after giving a bit of throttle and instant release engine work for few seconds on high rpm and go down. Carburetor foto:
Second: ATV a bit luckier It 200 cc 4-stroke engine, with china 125 cc carburetor, problem is engine works fine in low and high rpm, medium getting stalled. Carburetor foto: structure same as first one.
Please need help on these two ATV, thanks a lot for advices.

 

You could take the carbs apart and clean them out real good and see if this helps. If it doesn't, invest in buying a new carb. They are very inexpensive on eBay.