4) Cylinders Inspection - Rotax MMH-912 Series Maintenance Manual

3.13.4) Cylinders inspection

Effectivity 912/914 Series
Edition 1 / Rev. 3
BRP-Powertrain
Maintenance Manual
See Figs. 72-91, 72-92 and 72-93.
The running surface of the cylinder is "NICKEL-SILICON"coated. All 4
cylinders are identical. Clean the cooling fins (1) of the cylinder.
Remove oil carbon deposits from the top end (2) of the cylinder bore.
Clean sealing surfaces on top (3) and bottom sides (4) and inspect
cylinder.
Measure cylinder as shown in the following diagrams and enter the
readings (CY01/CY02/CY03) in the corresponding form sheet. See
72-00-00 sec. 4.
Measure the installation clearance, see 72-00-00 sec. 3.13.1. If the
wear limit for the cylinder has been reached, the cylinder and/or the
piston must be replaced.
◆ NOTE: Slight oil carbon residues on the cylinder sealing sur-
face (3) indicate leakage. True up the cylinder along
with the cylinder head.
◆ NOTE: If porosity is found in the cylinder wall the pores must
not exceed a diameter of 0.4 mm ( 0.015 in. ), the
distance between pores must be at least 8 mm (0.31
in.).
■ CAUTION : If the engine has been overheated, the hardness of the
cylinder must be checked. The hardness is measured
at control point CY04. See Fig. 72-93. See 72-00-00
sec. 5.1.
72-00-00
page 81
October 01/2010