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X9 Evolution 125
Engine
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 COM-
POUND 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 FIT-
TED IN
Characteristic
Valve check Standard length
Exhaust: 94.4 mm
Valve check Standard length
Inlet: 94.6 mm
Valve check Maximum admissible clearance
Exhaust: 0.072 mm
Valve check Maximum admissible clearance
Inlet: 0.062 mm
Valve check standard clearance
Exhaust: 0.025 ÷ 0.052 mm
Valve check standard clearance
Inlet: 0.013 ÷ 0.040 mm
Valve check Minimum admissible diameter:
Exhaust: 4.95 mm
Valve check Minimum admissible diameter:
Inlet: 4.96 mm
Valve check Standard diameter:
Inlet: 4.972 ÷ 4.987 mm
Valve check Standard diameter:
Exhaust: 4.96 ÷ 4.975 mm
- Measure the width of the sealing surface on the
valve seats and on the valves.
Sealing surface width: After use: Intake and dis-
charge: 1.6 mm
- If any of the sealing surfaces on the valves is
wider than the specified limit or is damaged in one
ENG - 129
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