CRANKCASE
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35
Leakage test
A leaking crankcase results in reduced crankcase compression. A typical sign is
that the machine is difficult to start.
Tools
The tool kit 544 10 33-01 consists of parts for sealing the cylinder's exhaust
and inlet ports as well as a sealing plug that replaces the decompression valve.
Pressure tester 531 03 06-23, or the like, is needed for the test.
Important
Turn the crankshaft so the exhaust port is fully open, i.e. the piston is at its
lower turning point.
Exhaust port
1. Fit the exhaust port seal on the cylinder
by the muffler's position.
The clutch lubrication channel
2. Tape over the clutch lubrication chan-
nel on the crankshaft. Does not apply to
machines with bearing-mounted clutch
drum.
Inlet port
3. Loosen the screws on the carburettor's
lower mounting a few turns.
4. Position the inlet seal and fit the
screw. Tighten the lower mounting with
care so that the clamp is not deformed.
Fit the sealing plug in the hole in the
cylinder for the decompression valve.
Test for leakage
Connect the pressure tester on the nipple at the axhaust port seal.
Pump a pressure to 7 psi/50 kPa. After 30 seconds the pressure may drop at
the most to 3 psi/20 kPa.
If a leakage is indicated
Find the leakage by brushing with soapy water or use a leakage spray. Check
the seals on the crankshaft first. Next check by the gaskets (crankcase halves,
base of the cylinder). Finally the possibility of cracks in the cast material of
the crankcase.
544 10 33-01
531 03 06-23
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