Bike is idling perfectly, new fuel filter, fresh fuel. The engine starts at 1/4 turn with choke, after warming up idles perfectly. When I open the throttle,( choke not on ) starts to fart out. When driving, when stopped on red lights ( I do stop on red lights hey hey ), adjusting the mix screw has no effect at all. The bike has poor acceleration and max speed is 70 mph ( engine is 88ci ).