Intake Boot for Husqvarna 385 385XP 390 390XP 537111402

Rubber intake pipe for the Husqvarna 385, 385XP, 390 and 390XP, replacing Husqvarna 537111402, which supersedes the earlier 537111401. Husqvarna's own term for this part is intake pipe; it is also sold as an intake boot, intake manifold or carburetor adapter. It sits between the carburetor and the cylinder intake port. Supplied as the boot on its own. The intake clamp is a separate part, 588775502. Also fits the heated handle and winter variants of these saws and the Jonsered 2186 and 2188 equivalents. The 576XP is a different and later platform and is not covered, and the 394XP and 395XP use their own intake sealing arrangement. Why this part matters: the boot is downstream of the carburetor, so a hardened or split boot admits unmetered air and leans the mixture. The symptoms are a creeping or hanging idle, an inability to hold a carburetor setting, erratic running between four stroking and over revving, and ultimately a scuffed piston on the exhaust side. A boot that looks sound can still leak warm or under flex. Husqvarna publishes a pressure test for these saws: blank the intake, pressurise to 80 kPa, which is 0.8 bar or about 11.6 psi, and after thirty seconds the pressure must not have fallen below 60 kPa. The service procedure removes the support ring from inside the intake and fits cover plate 502540501 with an M4 by 15mm bolt. Engine reference: 385XP is 84.7cc on a 54mm bore, 390XP is 88cc on a 55mm bore, and both use the same intake pipe. While the carburetor is off, check the impulse line and fuel line for hardness and the clamp for cracking, and pressure test the saw after fitting.

• THE RUBBER INTAKE PIPE BETWEEN THE CARBURETOR AND THE CYLINDER - Replaces Husqvarna 537111402, which supersedes the earlier 537111401. Husqvarna calls this part the intake pipe; it is also sold as an intake boot, intake manifold or carburetor adapter, and they are all the same thing. Fits the 385, 385XP, 390 and 390XP, including the heated handle and winter variants, and the Jonsered 2186 and 2188 equivalents. This is the boot on its own. The clamp is a separate part, 588775502.
• A HARD OR SPLIT BOOT IS A LEAN RUN, AND A LEAN RUN KILLS PISTONS - The boot sits downstream of the carburetor, so any crack lets in air the carburetor never measured. The saw goes lean. What you notice is the idle creeping up or hanging high after a blip, the saw refusing to hold a tune, and in the end a scuffed piston on the exhaust side. A boot that looks sound can still leak warm or under flex, which is why age alone is reason enough to change it on a saw of this value.
• HOW TO PROVE IT RATHER THAN GUESS - Husqvarna publishes a pressure test. Blank the intake, pressurise to 80 kPa, which is 0.8 bar or about 11.6 psi, and wait thirty seconds. The pressure must not fall below 60 kPa. Any more loss and there is a leak to find. The procedure removes the support ring inside the intake and fits cover plate 502540501. The quick version, spraying cleaner around the boot at idle and listening for a change in revs, finds a bad leak but will not clear a saw that passes.
• FITMENT, AND WHAT IS NOT COVERED - The 385XP is 84.7cc on a 54mm bore and the 390XP is 88cc on a 55mm bore, and Husqvarna uses the same intake pipe on both, so the displacement difference does not change the part. The 576XP is a later and different platform and is not covered here. The 394XP and 395XP use their own intake sealing arrangement and are not covered either, even though they share some carburetor parts with this family.
• WHILE THE CARBURETOR IS OFF - Check the impulse line and the fuel line for hardness, because they fail the same way and for the same reason as the boot. Check the clamp for a cracked ear. If you are chasing a tune, read your carburetor before ordering parts for it: the early 385XP ran an HS-290 and the 390XP a WJ-116, and the rebuild kits differ. Pressure test after the new boot is in, so you know the job is finished.