Checking Timing System Parts; Head And Timing System Parts Assembly - PIAGGIO 500 cc Service Manual

Thermal unit and timing system

Checking timing system parts

- Check that the guide shoe and the tension pad are not
excessively worn.
- Check that the camshaft control timing gear and
driving shaft pinion assembly show no signs of wear.
- Replace the pads, or the whole assembly if the chain,
or ring gear, are worn.
N.B.: If the chain has damaged the pinion, replace the
driving shaft as described in Chapter 8-Crankcase and
Driving Shaft.
- Remove the central screw with the washer and the
tightener spring. Make sure the unidirectional mecha-
nism shows no signs of wear.
- Check the tightener spring condition.
- If necessary, replace the whole assembly.

Head and timing system parts assembly

- Fit the chain guide shoe
- Fit the two centering dowels between the head and
the cylinder.
- Assemble the head gasket.
N.B.: The figure shows the assembly position of the two
centering dowels between the head and the cylinder.
The gasket assembly position is forced by the dowels.
The head gasket is made of steel and has a standard
thickness.
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