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• Head preparation
– Remove the carbon deposits and the gasket residues from the
head surface and from the combustion chamber.
– Carry out a valve seal test by pouring clean solvent in the inlet
and exhaust ducts, and check if there is any leak.
If there is a fl uid leak between valves and valve seats you have
to remove the valves and check the clearance between stems
and guides or ensure that the valves are not bent or worn.
Replace the unsuitable parts and remove the carbon deposits,
then proceed lapping the valves with the special abrasive paste.
Carefully clean the head and all parts, reassemble them and
carry out again the valve seal test.
Should it be necessary, the head lapping must be done by a qualifi ed
workshop. Otherwise place a damp sheet of glass paper (1000 grain)
on a surface plate and lap the head by moving it like an eight.
• Piston ring assembly
– Carefully clean the new piston, the piston rings and the gudgeon
pin circlips.
– Assemble one of the two gudgeon pin circlips on the piston, pay
attention not to stretch it, and check that it is placed correctly in
its seat.
– Fit the scraper ring expander in the special piston groove, then
complete the scraper ring assembly by fi tting fi rst the lower and
then the upper scraper ring (Fig. 4 - Part 1).
– Fit the second piston
ring with the printing
facing the piston upper
part as shown in Fig. 4
- Part. 2.
– Insert the fi rst chromed
compression piston ring
with the printing facing
the piston upper part as
shown in Fig. 4 - Part. 3.
– Position the piston rings
openings as shown in
Fig. 4.
– Notes:
symbol printed on the
piston rings may vary.
The
letter/
14
Fig. 4
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