M4
Mark on
gearcase
TDC mark for no. 1
and no. 4 pistons
TDC mark for no. 2
and no. 3 pistons
Injection timing mark
M4
M4
Valve clearance:
Inlet 0.25 mm
(0.010”)
Exhaust 0.25 mm
(0.010”)
73
6 Maintenance
Checking valve clearance
Every 500 operating hours.
46 Remove rocker cover
• Remove the 2 nuts of the rocker cover.
• Complete the following steps:
• Locate the Top Dead Center (TDC), at the
end of the compression stroke, for cylinder
1 by barring the engine slowly until the TDC
marks of the engine block and the crank
pulley match.
27
VD00130
VD00990
12
VD02037
12 1.2 x 6.5
47 Locating TDC 48 Adjusting valve clearance
• Check valve clearance at cylinder 1 and ad-
just if necessary.
• Rotate the crankshaft 180° clockwise and
check valve clearance at cylinder 3.
• Again rotate the crankshaft 180° and check
valve clearance at cylinder 4.
• Finally again rotate the crankshaft 180° and
check valve clearance at cylinder 2.
Note 1: There are two TDC’s e.g. compres-
sion and suction. At the TDC at the end of
the compression stroke the rocker arm does
not move when the crank pulley is rotated
a little.
Note 2: Cylinders are numbered consecu-
tively, beginning at the front end.
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