Defective oil seals, gaskets,
cracks in castings or a faulty sea-
ling ring between the carburetor
housing and cylinder are the usu-
al causes of leaks. Such faults al-
low air to enter the engine and
thus upset the fuel-air mixture.
This makes adjustment of the
prescribed idle speed difficult, if
not impossible.
Moreover, the transition from idle
speed to part or full throttle is not
smooth.
The crankcase can be checked
thoroughly for leaks with the carbu-
retor and crankcase tester and the
vacuum pump.
- Remove the carburetor - see
8.2.1 and 8.2.2.
- Set the piston to top dead center
(T.D.C.). This can be checked
through the inlet port.
- Make sure the spark plug is
properly tightened down.
•
Slide a new gasket over the
carburetor studs.
•
Push the test flange (1)
1128 850 4200 into position.
•
Fit and tighten down the nuts (2)
firmly.
- Back off the muffler mounting
screws half-way.
•
Slide the sealing plate (1)
0000 855 8106 between the
gasket and cylinder exhaust
port and retighten the mounting
screws moderately.
Note:The sealing plate must
completely fill the space between
the two mounting screws.
2
5
0
R
A
0
1
3
V
A
2
5
0
R
A
0
1
4
2
1
2
V
A
2
5
0
R
A
0
1
5
1
V
A
4.2 Leakage Test 4.2.1 Preparations
10 FS 120, 200, 300, 350, 400, 450, FR 350, 450
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