loss of power

So it all started when a screw for my exhaust broke inside the cylinder I tried to remove it every way possible, sadly it didn't work. I then got a replacement one online, when installing it I tightened it to much to the point that the cylinder head cracked. Unaware I tried to ride it and ended...

So I bought a Chinese 80/66cc engine off of Ebay, and it ran fine, I got it up to 40 mph. After break-in, I changed the carb out from the stock one to the hp one, and also added a boost bottle. When I started riding, It wouldn't go above 20 mph and the acceleration was super slow compared to...

Hey guys, I'm kinda new to the scene here but just a couple months ago, i purchased a cheap chinese model 49cc 2 stroke kit for my bicycle. I need it for my daily commute to work etc. Well, it ran perfect for about a month. Then, i started having carb trouble. First, i lost my idle screw...