Tillotson HU Carburetor Repair And Service
Tillotson HU Carburetor Manual and Parts List for the correct identification, repair and service of the Tillotson HU carburetors found in trimmers, chainsaws, blowers and other machinery. View free online images or download the full Tillotson HU Carburetor Manual PDF which can be printed or saved on any suitable device. Clear diagrams and information to help in parts ordering or repair of this Tillotson HU series carburetor. Identify all component parts of the Tillotson HU carburetor.
Tillotson HU Carburetor Manual
Carburetor Models covered in this workshop manual are:
Tillotson HU series
The Tillotson model number is stamped on the body of the carburetor.
The larger 8-32 diameter screw is your high-speed mixture. Heavy flooding is usually indicative of a carb in need of cleaning and a new kit properly installed & adjusted, stiff metering diaphragms can hold the needle off its seat and that allows heavy flooding.
The following procedure should be followed to ensure proper carburetor adjustment:
1 Check the air filter and clean it if necessary. Adjusting the carburetor with the air filter partly clogged is like adjusting the carburetor with the choke partially on. If you adjust your saw with a dirty air filter, the saw will run too lean when the filter is cleaned.
2 Check the muffler and exhaust port for carbon build-up. Carbon clogging the exhaust port or spark arrestor screen can cause a saw to run as if the carburetor requires adjustment. Changing the carburetor settings with a plugged muffler may result in the saw running to lean when the carbon build-up is cleaned out.
3 If carburetor adjustment is required due to a new or rebuilt carburetor, it is best to start with the fuel adjustment settings one turn out. This is accomplished by gently screwing the adjusting screws onto their seats and then backing them out one turn each. Care must be taken when screwing them onto their seats because the seats may be easily damaged if the adjustment screws are seated too hard. These seats are delicate and if they are damaged, the carburetor has to be replaced.
4 Check the fuel level. The tank should be over half full. If the carburetor is adjusted when the fuel tank is empty, the carburetor may be adjusted too rich when the fuel tank is filled.
5 Start the engine and warm it up. If the saw will idle let it run for a few minutes. If it will not keep up idle without stalling warm it up by repeatedly squeezing the throttle, do not run the throttle to wide open. Carburetor adjustments made on a cold engine will be too rich when it reaches normal operating temperature.
6 Begin by setting the idle speed. Try to set the speed at about 2700 RPM. If you don’t have a tachometer, try to set the speed so the saw idles as high as possible without engaging the clutch. Never set the idle so the chain runs when the throttle is released. If the saw will not idle, go to the next step.
7 Set the low-speed fuel adjustment. Slowly turn in the screw until the engine surges or starves for fuel. Make a mental note of the position of the screwdriver slot. Now slowly turn the adjustment screw out and the engine should run better. Keep turning the screw until the engine starts to load up. Make a note of the position of the screwdriver slot and compare it to the position of the lean adjustment. Now slowly turn in the screw to a position where it idles the best. It should be about midway between the rich and lean settings.
Tillotson HU Carburetor Manual PDF
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