what are the settings on a tilliotson carb for a 100cc gokart?

Answer 1

Are there two adjustment screws on the side or only one on the bottom of the float bowl. Is it a diaphragm or float Tillotson carburetor.
Are we working on a 2 cycle motor or a four cycle motor. E-mail and I can certainly talk you through either.
I had a 439cc triple cylinder Polaris Starfire Racer in 1972. It had one Tilliotsen carb. per cylinder.

If the motor is a two cycle motor the carb most likely has three adjustment screws in the left hand side. Idle speed, idle or low speed circuit (the second closest to the carb.) and the high speed circuit (furthest away from the motor).

First set the idle speed screw ( controls the amount the butterfly valve is open) till it idles smoothly. Turn the low speed mixture screw in clockwise slowely till the motor starts to drop RPM. Open it back up 1/2 turn. To set the high speed screw it's best to have the chain on the sprocket and lift the cart on jackstands so the rear wheels turn freely when the clutch engages. Squeeze the throttle quickly. If it stumbles or hesitates at all open the low speed mixture screw 1/8 of a turn till the hesitation stops.
The high speed adjustment is made with the throttle at the full open position. If you hear the motor double fireing as does most chainsaws, very slowly turn in clockwise the high speed mixture screw till the engine reaches an even sounding screaming RPM. Release the throttle and open it quickly. If there is a stumble at all open the high speed screw 1/8 turn at a time till the motor does not hesitate any longer. It's very importent NOT to leave the high speed mixture screw left open for maximum RPM. You must open (richen the fuel mixture) a minimum of a 1/4 turn by turning it counter clockwise. Reason being under load as the motor reaches it's highest RPM with a load on the cart the mixture will be too lean and you would burn a piston. If you hear the motor double fire while going as fast as you can turn in clockwise the high speed screw 1/8 of a turn clockwise. Stop as soon as the motor no longer double fires.

I wish I could demonstrate what double fireing actually is on my chainsaw then you'd now exactly what to listen for. If you want to hear it we could hook up by cell plone or land line. Let me know.

Answer 2

Start with this. Set the low speed needle at 1+1/2 turns out and the high speed needle at 1+1/8 turns out. Adjust the throttle stop screw on the carburettor so that it just cushions the butterfly when the throttle valve goes closed. Do not set the carburettor so that the engine will idle as this will cause the engine to lean out in the corners and anytime you are off the throttle.