49mm Nikasil Cylinder & Piston Kit for Stihl MS391 - 3-Bolt

A 49mm Nikasil cylinder and piston kit for the Stihl MS391, a straight replacement at the saw's 49mm bore. The kit contains the Nikasil-plated cylinder, piston, piston rings, wrist pin and circlips. This is the 3-bolt intake version: these cylinders were built with 3-bolt and 4-bolt intake manifolds, so count the bolts holding the intake to your old cylinder before ordering. It replaces cylinder assembly 1140-020-1204. While the saw is apart, check the crankshaft bearings for play and the crank seals for hardness, and pressure and vacuum test the crankcase, because a worn bearing or an air leak will score a new piston as quickly as the old one. Use a ring compressor on assembly, tighten the cylinder screws evenly, and check the carburetor setting once the saw is run in.

• 49MM CYLINDER AND PISTON FOR THE STIHL MS391 - A Nikasil-plated cylinder with piston, piston rings, wrist pin and circlips: a straight replacement at the MS391's 49mm bore.
• COUNT THE INTAKE BOLTS FIRST - This is the 3-bolt intake version. These cylinders were made with 3-bolt and 4-bolt intake manifolds; count the bolts holding the intake to your old cylinder before ordering. It does not fit a 4-bolt saw.
• REPLACES CYLINDER ASSEMBLY 1140-020-1204 - The 3-bolt intake version. If your parts list shows this number, match the bolt count and this kit covers it.
• CHECK THE BOTTOM END WHILE IT IS APART - Rock the crankshaft for bearing play and look at the crank seals. A worn bearing or a hardened seal will take out a new top end, so deal with either before the cylinder goes on.
• BEFORE THE NEW TOP END GOES ON - Pressure and vacuum test the crankcase and replace a cracked intake boot or split impulse line. Use a ring compressor, tighten the cylinder screws evenly, and check the carburetor setting once the saw is run in.