I replaced my 30mm carburetor after it sit for a year and the gas in it went bad, was corroded with varnish. I put a new fuel filter on it for lawn mower. It'll idle and rev pretty good. But soon as you take it for test drive it starts cutting out, you give it a bit of gas to accelerate it cuts out really bad and even backfired. I've thought maybe the cdi or coil is weak but ain't got those parts yet. I just tried to adjust fuel/air and the screw does nothing much at all but the idle screw works. I'm at my witts end. Gonna pull the spark plug out and give it a look after it cools down. Please help it's been a year since I rode it. It's a Lifan Hi-Bird QH250GY. A 2007. Thanks