50 – English
Repair instructions
Cleaning and checking
Clean all parts, scrape off all gasket residue and
carbon from the following places:
• The piston crown
• Top of the cylinder bore (inside)
• The cylinder exhaust port
• The base of the cylinder and/or crankcase
See fi gure
82.
Fig 82
Fig 83
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 chafe or
cutting marks.
• That the piston is free from cutting marks.
Minor scratches can be polished of
f using fi ne
emery paper.
• That the piston ring is not welded to its track.
• Remove the piston ring from the piston to mea-
sure the wear
. Use the bottom of the piston to
press down the piston ring into the cylinder.
The opening of the ring must not exceed 1
mm. Put the piston ring back into the piston
slot and make sure it is the right way around,
see fi gure 83.
• That the needle bearing is intact.
• That the inlet bellows is intact.
• That air hoses and impulse hose are intact.
7
Remove the seals and the circlip. Carefully pull out
piston and crankshaft. Cover with paper over the
cylinder opening to prevent dirt from coming in.
8
Carefully loosen the circlips D, see fi
gures 80 and
81, with a small screwdriver.
Fig 79
Fig 80
Fig 81
9
Press out the gudgeon pin E. Now lift off the piston.
Remove the covers F and the needle bearing G.
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