My brother's '85 200 Moto 4 cuts out and nearly stalls occasionally when it's idling and at lower rpms. Here's a video of what it's doing. Also, if I adjust the idle so it will stay running when it's cold, it revs higher as it warms up, to the point that it's almost like having cruise control. So far I've cleaned the carburetor and drained the tank and put new gas in it. Any ideas what else I might try?

https://www.youtube.com/watch?v=aITK...ature=youtu.be

 

Hook a timing light up to the plug wire and as you have it idling and also when reving up and see if the light is continuous or flashes intermittently in time with the engine miss. If the light is intermittent,then it's probably an electrical related problem. Plug,plug wire,plug cap,or even a coil or cdi problem.If the light is continuous,then it could still be fuel/carb or mechanical related problem.