I have a 2000 king quad 300 that i got for a steal but it wont idle. It will start and run with very little throttle like even a 1/16 throttle it will run but it dies as soon as i let go. I have cleaned the card compressed air amd it made no difference. I think the previous owner did attempt to adjust the carb somehow so that may have somthimg to do with it. Any help is appreciated!

 

also rode it around the yard today and backfires it backfires when given more than about 1/2 throttle