PIAGGIO 633929(IT), Service Station Manual, Page: 137 / 314

Inspecting the cam shaft
- Inspect the cam shaft for signs of abnormal wear
on the cams.
- Check the cam height.
- Check there is no wear on the cam shaft retaining
plate and its associated groove on the cam shaft.
- If any of the above dimensions are outside the
specified limits, or there are signs of excessive
wear, replace the defective components with new
ones.
- Check there are no signs of wear on the auto-
matic valve-lifter cam, or the end-of stroke roller,
or the rubber buffer on the automatic valve-lifter
retaining cover.
- Check that the valve lifting spring has not yielded.
- Replace any defective or worn components.
- Check the rocker pins do not show signs of wear
or scoring.
- Measure the internal diameter of each rocker
arm.
Check there are no signs of wear on the pad from
contact with the cam and on the jointed adjustment
plate.
Characteristic
Internal rocker arm diameter: Standard diame-
ter
Diameter 12.000 - 12.011 mm
Rocker arm pin diameter: Standard diameter
Diameter 11.977 - 11.985 mm
MP3 125
Engine
ENG - 43