How to Adjust a Tillotson Carburetor

by Carl Pruit

The Tillotson carburetor is used on small engines designed primarily for go-carts. You can adjust the carburetor in just a few minutes. The carburetor uses a low-speed and high-speed set screw that you can adjust fairly easily with just a screwdriver. The high-speed set screw includes a "T" on the end, allowing you to adjust the screw by hand.

Step 1

Locate the idle set screw at the very bottom of the Tillotson carburetor. Turn it clockwise with a screwdriver until you completely close it without over-tightening the screw.

Step 2

Find the low-speed adjustment screw with the "L" next to it on the carburetor body. Turn the low-speed screw all the way clockwise and back it out counterclockwise one and a half turns.

Step 3

Locate the high-speed adjustment screw with the "H" on the body. Turn the high-speed screw all the way clockwise and back it off counterclockwise three-quarters of a turn.

Step 4

Start the motor and let it warm up for a few minutes. If the engine is having trouble starting, adjust the low-speed screw just a bit to get it started.

Step 5

Turn the low-speed screw until you can hear the motor slow down. Adjust the screw as slow as you can get the engine to run without stalling out.

Step 6

Open the carburetor throttle all the way and adjust the high-speed screw as high as it will go while still running smoothly. Turn the high-speed screw back one-eighth and shut off the engine.

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