I know its cars but... moped problem, any help?

[racer11]

i got a honda sgx sky (little 50cc thing), and when i slowly turn the throttle you can hear the revs pick up then once at a certain highish rev count the bike engages and accelerates considerably not smoothly (but not jerky) from these higher revs than idle. anyone know how to change this!? and smooth it out?

thanks