I have searched everywhere for a solution to my problem but still have not fixed it. when i give throttle it will bog , if i slowly twist the throttle it will build up , however it will bog when i twist the throttle quickly or if i try to drive it . The valve clearances are in spec and the timing is right , i have cleaned the carb a few times and have played with the fuel mixture screw which did help a little but not enough. i noticed that there seemed to be blowback in the carb (air was blowing back through carb).the bike was running fine until the cam journal was overtightened and warped , this meant that the cam would not turn easily, i have fixed that now and now it bogs , i also noticed that it seems quite easy to kick , but that might be because before the cam was so tight it was harder to kick. I really do not know whats up with it ??