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• In order to turn the engine, use
the close bolt of the crankshaft.
• Unscrew the screw of the chain
adjuster using a screwdriver.
Insert the screwdriver into the
hole and turn clockwise the
screw till complete locking,
(Fig. 4, part.
5).
• Remove the chain adjuster and
the crown gear taking care not
to let the gearing chain fall on
the crankcase.
• Unscrew the 4 M6 screws
which fix the rocker cover and
remove it
(Fig. 5, part.
• Remove the two screws which
fix the cylinder head to the
engine block.
• Screw out the four nuts
(Fig. 6, part.
7).
• Remove the cylinder head and
the original cylinder from the
crankcase of the engine.
• Remove the piston from the
connecting rod.
• As an extra precaution to
prevent foreign matter from
entering the crankshaft block,
it is best to close the block with
a clean cloth.
Cylinder head assembly
If the scooter does not have much
mileage, we recommend you
to perform the valve tightness
test in any case, following the
instructions found in the section
entitled "Valve tightness test".
6).
If the scooter has registered a
lot of mileage, it is advisable
to disassemble the valves and
check to ensure that there is not
excessive clearance between the
valve stem and the guides, that
the valves are not bent or present
unevenness or a worn head.
Even if only one of these
conditions is found to exist,
we advise you to replace both
components, as well as the valve
return springs, if the latter are not
in perfect condition.
If it is necessary, consult the
"Useful suggestions".
In the event of valve guide
replacement for both assembly
and disassembly, the head must
be heated prior to the procedure
with a hair-dryer or electric hot
plate. After the replacement
of the guides, re-condition the
valve seats with a specific milling
machine in order to restore
them. Then grind the valve with
abrasive paste and remove any
remaining deposits and abrasive
paste from the head and all head
components.
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