APRILIA MXV 450 - Page 110

•
Use a micrometer to measure the valve
stem (C) diameter.
•
Use an internal micrometer to measure
the valve guide (D) inside diameter.
Characteristic
Valve stem diameter - minimum limit
4.96 mm (0.1952 in)
Check the clearance (G) between stem and valve guide as follows:
G = D - C
Characteristic
Stem - valve guide clearance - maximum limit
0.08 mm (0.0031 in)
•
If the clearance is not within the speci-
fied values, replace the valve guide.
•
Proceed to check the valves and valve
guides by removing the carbon depos-
its from the valve face and seat.
•
Check that the valve face does not
show cracks and signs of wear; other-
wise, replace the valve.
•
Check that the end of the valve stem is
not distorted (mushroom-shaped) and
that its diameter does not exceed the
stem body diameter; otherwise, re-
place the valve.
•
Check that the value (E) of the valve
support plane of the valve rims is within
Engine MXV 450
ENG - 110