PIAGGIO Beverly Tourer 250 i.e. Service Station Manual page 133

Beverly Tourer 250 i.e.
Inspecting the valves
- Measure the width of the sealing surface on the
valve seats and on the valves.
Sealing surface width: After use: Intake and ex-
haust: 1.6 mm
- If any of the sealing surfaces on the valves is
wider than the specified limit or is damaged in one
or more points, or curved, replace the valve with a
new one.
CAUTION
DO NOT REVERSE THE FITTING POSITIONS OF THE
VALVES (RIGHT - LEFT).
Characteristic
Valve wear check Standard: Intake and ex-
haust:
0.99 - 1.27 mm
- Measure the diameter of the valve stems in the three positions indicated in the diagram.
- Calculate the clearance between valve and valve guide.
- Check that there are no signs of wear on the surface of contact with the articulated register terminal.
- If the checks above give no failures, you can use the same valves. For best sealing results, it is
advisable to grind the valves. Grind the valves gently with a fine-grained lapping compound. 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 FAYING SURFACE, DO NOT KEEP ROTATING 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.
N.B.
DO NOT CHANGE THE POSITIONS THE VALVES ARE FITTED IN
Characteristic
Valve check standard length
Outlet: 94.4 mm
Valve check standard length
Inlet: 94.6 mm
Valve check Maximum admissible clearance
Outlet: 0.072 mm
Valve check Maximum admissible clearance
Inlet: 0.062 mm
Valve check standard clearance
Outlet: 0.025 ÷ 0.052 mm
Engine
ENG - 133