Carburetor rebuild kit for Tillotson HS series carburetors on vintage Homelite chainsaws. TILLOTSON ONLY - READ YOUR CARBURETOR FIRST Homelite built these saws with more than one make of carburetor. Some are Tillotson HS, some are Walbro SDC, and some have been replaced with Zama units over the years. This kit is for the TILLOTSON HS series. It will not fit a Walbro SDC and it will not fit a Zama. To check: take the air filter cover off and read what is cast or stamped into the carburetor body. A Tillotson reads HS followed by a number, such as HS-151A or HS-142A. If it reads SDC, that is a Walbro and you need a Walbro kit. WHAT IS IN THE KIT Metering diaphragm Metering diaphragm gasket Fuel pump diaphragm Fuel pump gasket Flange gasket Inlet needle Inlet control lever Inlet screen Welch plugs There is NO inlet seat in this kit and none is needed. On a Tillotson HS the rubber tipped inlet needle seats directly on a machined orifice in the carburetor body casting. There is no replaceable seat, so do not go looking for one and do not pick at the orifice. SAWS AND CARBURETORS COVERED One family - XL12, Super XL, XL15, XL400 and XL500. Tillotson numbers seen on these include HS-4D, HS-96A, HS-142A, HS-179B and HS-195A. The other family - XL700, XL901, XL921, XL923, XL924, XL925, SXL925, VI-944 and VI-955. Tillotson numbers seen on these include HS-26, HS-56, HS-73, HS-86, HS-103, HS-120A, HS-131B, HS-134, HS-135, HS-142 and HS-151A. These are two distinct saw families with different carburetor part numbers. What they have in common is the Tillotson HS series carburetor, which is what this kit is for. If you tell us the HS number off your carburetor we can confirm it before you order. A FEW NOTES ON THE SAWS XL12 - introduced in the early 1960s, the first of the light magnesium saws, around 3.55 cubic inches. Super XL - 3.55 cubic inches, 57.4cc, from the late 1960s. SXL925 and XL925 - a larger frame saw of around 5 cubic inches. VI-944 and VI-955 - large frame saws in the same family as the XL700 to XL925 group. REBUILDING ONE - THE PARTS THAT MATTER DIAPHRAGM STACK ORDER. This is what catches people out. The pump diaphragm goes next to the metering body, then the gasket. Then the main diaphragm gasket, then the main diaphragm. Get this backwards and the carburetor will not pump fuel no matter how clean it is. Take the old parts off in order and lay them out on the bench in that order. INLET CONTROL LEVER HEIGHT. The lever is right when it sits FLUSH with the floor of the diaphragm chamber. There is no gauge dimension to chase on these - flush is the specification. If it sits low, lift the diaphragm end gently. If it sits high, hold it down and push on the needle. WELCH PLUGS. The body channel plug is 11/32 inch. Drill a 1/8 inch hole and just break through it - drilling deeper will damage the body casting and there is no fixing that. The main nozzle plug takes a 1/16 inch drill. Fit the new plugs convex side up and flatten them with a flat tool slightly larger than the plug. THE INLET NEEDLE. It is rubber tipped and seats on the casting. Do not lap it, do not pick at the orifice, and do not over tension the lever. BEFORE YOU BLAME THE CARBURETOR Squeeze the fuel line. On saws this age it is usually hard, cracked or swollen, and a collapsing line starves the carburetor no matter how well you rebuild it. Check the tank vent. A blocked vent pulls a vacuum in the tank and the saw dies after a minute or two of running, which feels much the same as a carburetor fault. Check the fuel pickup filter in the tank. Check the impulse line to the crankcase - no impulse, no pumping.
- TILLOTSON HS CARBURETORS ONLY - CHECK YOURS BEFORE ORDERING - Homelite fitted BOTH Tillotson and Walbro carburetors to these saws, and there are Zama replacements out there too. This kit is for the TILLOTSON HS series. It will not fit a Walbro SDC or a Zama. Take the air filter cover off and read the make and model stamped on the carburetor body - on a Tillotson it will read HS and a number. Thirty seconds now saves you the whole job.
- WHAT IS IN A COMPLETE KIT - Metering diaphragm and its gasket, fuel pump diaphragm and its gasket, flange gasket, inlet needle, inlet control lever, inlet screen and welch plugs. Note that these carburetors have no replaceable inlet seat - the rubber tipped needle seats directly on a machined orifice in the carburetor body, so there is no seat to change and none is needed.
- FITS THE TILLOTSON HS CARBURETORS ON THESE SAWS - XL12, Super XL, XL15, XL400 and XL500 in one family, and XL700, XL901, XL921, XL923, XL924, XL925, SXL925, VI-944 and VI-955 in the other. Those are two different saw families with different carburetor numbers, and what ties them together is that they all run Tillotson HS series carburetors that this kit covers.
- THE ONE THING THAT STOPS A REBUILT CARB PUMPING - The diaphragm stack order is not obvious and getting it wrong is the reason most rebuilt Tillotsons will not pull fuel. The pump diaphragm goes next to the metering body, then its gasket. Then the main diaphragm gasket, then the main diaphragm. Lay the old parts out in order as they come off and you will not go wrong. Set the inlet control lever flush with the floor of the diaphragm chamber - flush is the spec, there is no gauge figure.
- CHECK THE FUEL SIDE BEFORE YOU BLAME THE CARBURETOR - These saws are old enough that the fuel line is usually hard or cracked and the tank vent is often blocked, and both of those feel much the same as a bad carburetor. Squeeze the line. If it is stiff or it crumbles, replace it. Blow the tank vent through. A clean rebuild on a carburetor fed by a collapsed line will still not run.