Inspecting The Cylinder - PIAGGIO MSS Fly 50 4T Workshop Manual

Engine
- Measure the coupling clearance between the sealing rings and the piston grooves using a thickness
gauge, as shown in the figure.
- If the clearances detected exceed the limits specified in the table, the piston and the piston rings should
be replaced.
Name
Top piston ring
Middle piston ring
oil scraper

Inspecting the cylinder

- Using a bore meter, measure the inner cylinder
diameter at three different points according to the
directions shown in the figure.
- Check that the coupling surface with the head is
not worn or misshapen.
- Pistons and cylinders are classified into catego-
ries based on their diameter. The coupling is car-
ried out in pairs (A-A, B-B, C-C, D-D).
Characteristic
Maximum allowable run-out:
0.05 mm
- The cylinder rectifying operation should be car-
ried out with a surfacing that respects the original
angle. at 120° crossed.
- The cylinder surface roughness should be of
R.A.= 0.30 ÷ 0.50.
- This is indispensable for a good seating of the
sealing rings, which in turn minimises oil consump-
tion and guarantees optimum performance.
ENG - 88
PISTON
Description Dimensions
0.030 ÷ 0.065 mm
0.020 ÷ 0.055 mm
0.040 ÷ 0.160 mm
MSS Fly 50 4T
Initials Quantity
0.080 mm
0.070 mm
0.20 mm