Inspecting The Valve Housings; Inspecting The Valves - PIAGGIO X8 125 Workshop Manual

Engine

Inspecting the valve housings

- Check the width of the imprint on the valve
seat«V» wear limit max. 1.6 mm.
- Remove any carbon formation from the valve
guides.
- Measure the inside diameter of each valve guide.
- Take the measurement at three different heights
in the rocker arm push direction.
- If the width of the impression on the valve seat or
the diameter of the valve guide exceed the speci-
fied limits, replace the cylinder head.
Characteristic
Valve seat wear Intake guide
limit accepted: 5,022
Valve seat wear Intake guide
Standard diameter: 5.000 ÷ 5.012 mm
Valve seat wear Exhaust guide
Accepted limit 5.022
Valve seat wear Exhaust guide
Standard diameter: 5.000 ÷ 5.012 mm

Inspecting the valves

- 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 fay-
ing surface with the articulated set screw terminal.
- If no anomalies are found during the above
checks, 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. Upon 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).
ENG - 136
X8 125-200