So I have two Yamaha Badger 80's with the same problem. They start and idle great when first started up. After a short ride they will bog down and stall when the throttle is let off of. The only way to get them started again is by turning on the choke. I have cleaned out the carb and replaced the float needle. I have also adjusted the valves and still have the same problem. I am hoping that somebody can point me in the right direction!