I have a 2000 or so King Quad 300 that idles perfectly fine, but hitting the throttle starts a chugging (choke position does not effect it) sound. Will not move. I have had this problem a long time ago, but it mysteriously went away. Last time this happened, I took the carb apart several times to clean it and it this had no effect...it still did it when reassembled. I am not wanting to start an exploratory project again...so any help would be appreciated. It was running fine until this problem started to come on slowly, now it is pretty bad. I will try to attach a video in a bit.

 

Forgot to mention that it is fine when started cold, problem arises as soon as the engine warms up.

 

Try a new plug and take a look at the old one's nose, black and sooty means too rich. If it is, the most likely cause is stuck float needle, choke or dirty air filter (could be fuel in airbox on Suzukis). If there is fuel in airbox, check that it hasn't got into engine and thinned the oil. The cause will be stuck float needle, plus either you running with tap on Prime, or faulty fuel tap. Another possibility for a sooty plug is the tap leaking fuel down the vac pipe, enriching the mixture.