Any suggestions would be great. So the sled always starts on the 3rd or 4th pull, which i think is good. It idles fine to warm up. then i ride it for a few kilometers and always seems to lose power (no more full throttle). Feels like it still runs on 2 cylinders, just nothing past half or 3/4 throttle. If i stop and let it idle at this time it'll pop or backfire thru the exhaust for a few minutes then all is ok. I can run it at half throttle for a few minutes and it seems to clear up. But it all happens again. Fuel pump was rebuilt, carb was torn down and cleaned, same settings, however i have tried minor adjustments, new filter, new fuel lines, new plugs. Not sure which way to go now.