Cylinder base gasket and muffler gasket for Husqvarna 150BT and 350BT backpack blowers. WHAT IT REPLACES Cylinder base gasket - Husqvarna 502848801 Muffler and exhaust gasket - Husqvarna 511494201, also listed as 511496901 FITS Husqvarna 150BT, 150BF, 350BT, 350BF The BF is the same engine on a different frame, not a handheld. THE ENGINE. 50.2cc, 44mm bore, X-Torq two stroke. DOES NOT FIT 2021 AND NEWER. This matters and there is no way to see it. Husqvarna redesigned this engine and the new generation shares no parts with the old - it uses cylinder gasket 535316801 and piston 531147153. The bore stayed at 44mm, so measuring will not tell you which you have. Read the serial number off the machine tag. Husqvarna serials begin with the year, so a serial starting 2018 is a 2018 machine. WHAT THESE GASKETS ACTUALLY DO. The cylinder base gasket seals the crankcase. When it hardens and leaks, the engine draws unmetered air, runs lean and loses power - and a lean two stroke eventually scores its piston. The muffler gasket blows out from heat cycling. WHILE THE CYLINDER IS OFF Carburetor gasket - 502845301 Insulator gasket - 502845501 Air filter - 502844401 Spark plug - 503235111 Spark arrester screen - 502845801 And check both crankshaft seals. If this blower scored a piston, an air leak caused it, and a new piston fitted over the same leak fails the same way.
- FITS THE 150BT AND 350BT BACKPACK BLOWERS - 50.2cc, 44mm bore. Cylinder base gasket replaces Husqvarna 502848801. Muffler and exhaust gasket replaces 511494201, also sold as 511496901. Also fits the 150BF and 350BF, which are the same engine on a different frame.
- CHECK YOUR SERIAL NUMBER BEFORE ORDERING - Husqvarna redesigned this engine and the new generation shares no parts with the old one. The new engine uses cylinder gasket 535316801 and piston 531147153; neither of these gaskets fits it. The bore stayed at 44mm through the change, so there is no visual tell - the serial number on the machine tag is the only check.
- WHY THESE GASKETS FAIL - The cylinder base gasket is what seals the crankcase, and a blower that has lost power, will not hold an idle, or runs hot and lean is very often drawing air past a hardened base gasket rather than suffering anything expensive. The muffler gasket blows out from heat cycling and leaks exhaust into the shroud.
- DO THE INTAKE GASKETS WHILE YOU ARE IN THERE - The carburetor gasket 502845301 and the insulator gasket 502845501 come off with the cylinder anyway, and an air leak on the intake side gives exactly the same symptoms you were trying to cure. The air filter is 502844401 and the spark plug is 503235111.
- IF YOU ARE IN HERE FOR A SCORED PISTON - Find the air leak before you rebuild. A blower that scored its piston once will do it again on the new one if the crankshaft seals or the base gasket are still letting air in. Check both seals while the cylinder is off. The spark arrester screen, 502845801, clogs on these and causes the low-power symptom people blame on the engine.