Hi I have a black 80cc engine that I got off eBay. It’s done a 1000km according to my speedometer at 750km I change the fuel mixture from 16:1 to 20:1 after I did that the engine started bogging I got rid of that by replacing the spark plug. But the engine still has a hard time accelerating compared to what it used to do. I also have to pedal a bit to make it start unlike before when I just let out the clutch and the engine took over just fine. I tied changing the little clip on the jet needle to make it leaner but that made a tiny difference. I can’t figure out what it is but I think it has something to do with the engine not getting enough air or fuel. Also a few days ago the engine refused to start. I got it going by taking of the carburetor, air filter and draining the fuel tank by the drain screw on the carburetor bowl. If anyone has any idea on what it would be i will greatly appreciate it.