Hello, new to the site!
Buyang 300, long story short, working on it for a friend. Ignition was bad (replaced with new), water in tank (flushed/soaked with Seafoam, dried), water in carb (soaked, cleaned, brass brushed every orifice, jet, etc.) I actually did the carb twice because when I put it back on I had a small leak) New fuel lines, new fuel filter.

Now it fires up real quick, will idle all day long, but if you give it throttle, immediate bog and dies. Thinking choke, (it's electric) but not for sure. Any ideas???

Thanks in advance. Shawn

 

unplug the choke and see what happens.

 

your ratio of air vs fuel is increasing therefore you have a fuel delivery issue. you have more air than fuel when increasing throttle. look over your main jet again, pull and clean. on your choke, if you can cold idle with choke, then that's good. after it gets warm, your choke can kill the quad by overfueling it. not enough air. once warm, then you don't need the choke anymore. so, look over the main jet again. thanks.