VESPA 946 E4 EMEA 2021 Manual page 41

Vespa 946 E4-E5 EMEA-USA-ASIA (2021-)
- After measuring the valve guide diameter and the
valve stem diameter, check clearance between
guide and stem.
- Calculate the clearance between the valve and the valve guide.
Specification
Standard clearance:
Limit allowed:
Specification
Standard clearance:
Limit allowed:
- Check that there are no signs of wear on the
mating surface with the set screw articulated ter-
minal.
- If no anomalies are found during the above checks, you can use the same valves. To obtain better
sealing performance, grind the valve seats. Grind the valves gently with a fine-grained lapping com-
pound. During the grinding, keep the cylinder head with the valve axes in a horizontal position. This will
prevent the lapping compound residues from penetrating between the valve stem and the guide (see
figure).
CAUTION
TO AVOID SCORING THE MATING SURFACE, DO NOT ROTATE THE VALVE WHEN NO LAPPING
COMPOUND IS LEFT. CAREFULLY WASH THE CYLINDER HEAD AND THE VALVES WITH A
SUITABLE PRODUCT FOR THE TYPE OF LAPPING COMPOUND BEING USED.
CAUTION
DO NOT REVERSE THE FITTING POSITIONS OF THE VALVES (RIGHT - LEFT).
INTAKE
EXHAUST
Technical Data
Desc./Quantity
0.10 mm
0.08 mm
Desc./Quantity
0.15 mm
0.1 mm
DT - 41