You could have a partially plugged exhaust. You would need to take it off and blow compressed air through it and see.
You might also match up the gasket on the exhaust and the intake. What I mean by this is see where the gasket is over hanging the openings and trim off the excess.
It will take a little time for these to break in most do need breaking in as they do you will notice an increase of power and the engine will smooth out. I know my first bikes engine, the speed and performance was for no better words SUCKED until I got it broke in. I switched to 32 to 1 mix after about one or two tanks of fuel. I was hooked on them and now have 4 (anyone need a bike?) I've done things to try and make them run better porting polishing tuned? pipe that I make and then I make lights for these so I ride most of the time after dark when its cooler summers in Texas are very warm for a X Wyomingite.
Keep plunking away it will do one of 2 things get better or get worse
Let me know as I'm here to try to help even if I just BSed my way through this time.