Leakage Testing The Crankcase; Preparations - Stihl 064 Service Manual

STIHL 064, 066
4.6 Leakage Testing the
Crankcase
Top:
Carburetor and crankcase tester
1106 850 2905
Bottom:
Vacuum pump 0000 850 3500
Defective oil seals and gaskets or
cracks in castings are the usual
causes of leaks. Such faults allow
supplementary 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
accurately for leaks with the car-
buretor and crankcase tester and
the vacuum pump.
4.6.1

Preparations

Top:
Muffler upper casing mounting screws
Bottom:
Muffler lower casing mounting screws
- Take out the muffler upper cas
ing mounting screws and remove
the upper casing.
- Slacken off the muffler lower cas-
ing mounting screws about half
way.
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