Piaggio Fly 4T servicemanual - Scootergrisen
Piaggio Fly 4T servicemanual - Scootergrisen
Piaggio Fly 4T servicemanual - Scootergrisen
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Engine MSS <strong>Fly</strong> 50 <strong>4T</strong><br />
- Measure the coupling clearance between the sealing rings and the piston grooves using a thickness<br />
gauge, as shown in the figure.<br />
- If the clearances detected exceed the limits specified in the table, the piston and the piston rings should<br />
be replaced.<br />
PISTON<br />
Name Description Dimensions Initials Quantity<br />
Top piston ring 0.030 ÷ 0.065 mm 0.080 mm<br />
Middle piston ring 0.020 ÷ 0.055 mm 0.070 mm<br />
oil scraper 0.040 ÷ 0.160 mm 0.20 mm<br />
Inspecting the cylinder<br />
- Using a bore meter, measure the inner cylinder<br />
diameter at three different points according to the<br />
directions shown in the figure.<br />
- Check that the coupling surface with the head is<br />
not worn or misshapen.<br />
- Pistons and cylinders are classified into catego-<br />
ries based on their diameter. The coupling is car-<br />
ried out in pairs (A-A, B-B, C-C, D-D).<br />
Characteristic<br />
Maximum allowable run-out:<br />
0.05 mm<br />
- The cylinder rectifying operation should be car-<br />
ried out with a surfacing that respects the original<br />
angle. at 120° crossed.<br />
- The cylinder surface roughness should be of<br />
R.A.= 0.30 ÷ 0.50.<br />
- This is indispensable for a good seating of the<br />
sealing rings, which in turn minimises oil consump-<br />
tion and guarantees optimum performance.<br />
ENG - 88
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