Tao Tao 150cc Suddenly Bogging Down, Sputtering, Help!?  By  jasong (Read 19,229 times)

Follow this procedure you can print it out so you have it when you adjust the carb. Probably the reason it is a little low on the top end is RPMS. Does your scoot have a tach on it?
Alleyoop

itistheride.boards.net/thread/12/4ts-carb-tuning

Concerning the jets:
If when adjusting the carb IF you have to turn the fuel ratio screw out more than 3 1/2 turns to get the highest RPM at IDLE then you need the next bigger PILOT JET. If you turn the Fuel Ratio Screw Clockwise until it stops and it does not kill the motor then the PILOT JET is to big you need the next smaller Pilot Jet. A good Pilot Jet it should adjust and get the highest RPM at idle anywhere from 2-3 turns out from the closed position(THIS ALSO DEPENDS on the amount of air that it's sucking in).

But a good rule of thumb is if you add a free flow filter you upjet the MAIN JET by 2 sizes. If you ALSO add a free flow exhaust you add ANOTHER 2 sizes to the MAIN JET(all toll 4-5 size bigger than what the carb came with). The pilot usually does not need to be changed unless you put in a BBK of a good size then you might need the next bigger PILOT JET.
Alleyoop