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Cleaning and inspection of the cylinder
Clean all components, and scrape off all gasket
remains and soot from the following areas:
•
The piston crown
•
The top of the cylinder (inside)
•
The cylinder exhaust port
•
The decompression valve channel
•
The base of the cylinder and/or crankcase
Check the following:
•
That the cylinder's surface coating is not worn.
Especially the upper part of the cylinder.
•
That the cylinder does not have any wear or
scoring.
•
That the piston is free of scoring. Minor scratch-
es can be polished off using fine emery paper.
•
That the piston ring is not welded in its groove.
•
Measure the wear on the piston ring. This must
not exceed 1 mm. See figure 62. Use the pis-
ton to push the piston ring downward.
•
That the gudgeon pin bearing is intact.
•
That the intake bellows is intact.
•
That air hoses and impulse hose are intact.
•
Pressure test the decompression valve. Carry
out pressure testing on the decompression
valve as follows.
A Connect the pressure gage 531 03 06-23 to
the decompression valve.
B Pump up the pressure to 80 kPa (0.8 bar).
C Wait for 30 seconds.
D The pressure must not fall below 60 kPa
(0.6 bar).
Faults and causes
Score marks on the piston (A).
1. Leakage, check not carried out.
2. Too low octane fuel.
3. Too little or incorrect oil in the fuel.
Carbon build-up (B)
1. Too much or incorrect oil in the fuel.
See figure 63.
Piston ring breakage
1. Piston ring worn out.
2. Oversized piston ring groove.
Fig 62
A
Fig 63
Repair Instructions
B
48
English –
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