4) Cylinder Head Fitting - Rotax MMH-912 Series Maintenance Manual

3.16.4) Cylinder head fitting

Effectivity 912/914 Series
Edition 1 / Rev. 3
BRP-Powertrain
Maintenance Manual
See Figs. 72-107, 72-108, 72-109 and 72-110.
Install respective pushrods (1) in both oil return tubes on the pre-
assembled cylinder head and place pre-oiled O-ring (2) 16x5 on oil
return tube (3).
Fit cylinder head until the O-rings (2) on both oil return tubes rest in the
crankcase (4). Now lift cylinder (5) until the centering (6) of the cylinder
engages in the cylinder head recess.
◆ NOTE: This is a safety measure to prevent jamming of cylinder
head resulting in leakage.
◆ NOTE: On engines of older design, washers (12) are fitted on
the hex. nuts M8. Recent findings show that it is no
longer necessary to fit these washers. These washers
are therefore not necessary when fitting a new cylinder
head.
■ CAUTION : Lightly grease the flat surfaces of the collar cap nuts
(11) to ensure a constant tightening torque.
Fit cylinder head and cylinder together on crankcase. First, slightly
tighten the cylinder head with 2 collar cap nuts M8 and 2 hex. nuts M8
crosswise. Ensure that the O-rings (2) are squeezed evenly into the
crankcase.
Repeat this procedure on the other cylinder heads.
Attach cylinder aligning tool (8), part no. 877262, to the intake flange
of the cylinder heads (10) with 4 allen screws (9) M6x25. Align cylinder
heads, thus warranting a flat support for intake manifold. Screw on
collar cap nut and flanged nut (11) with washer (12) and tighten cylinder
heads in the order shown in Fig.72-108. Tighten to 10 Nm (90 in.lb) and
then in addition tighten further by applying a 180° rotation. Remove 4
allen screws (9) and cylinder aligning tool.
◆ NOTE: If cylinder stud heads are damaged or if the cylinder
baffle clearance is too tight then the cylinder head studs
have to be replaced.
Lubricate all moving parts in rocker arm compartment. Place O-ring (13)
105x2.5 and O-ring (14) 6.4x1.8 in the valve cover (15).
72-00-00
page 92
October 01/2010