Piaggio Fly 4T servicemanual - Scootergrisen
Piaggio Fly 4T servicemanual - Scootergrisen
Piaggio Fly 4T servicemanual - Scootergrisen
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MSS <strong>Fly</strong> 50 <strong>4T</strong> Engine<br />
- The pistons are oversized due to cylinder rectifi-<br />
cation and are subdivided into two categories 1st<br />
and 2nd with 0.2-0.4mm oversize. They are also<br />
classified into 4 categories A-A, B-B, C-C, D-D.<br />
Inspecting the piston rings<br />
- Alternately insert the three sealing rings into the cylinder, in the area where it retains its original di-<br />
ameter. Using the piston, insert the rings perpendicularly to the cylinder axis.<br />
- Measure the opening, see figure, of the sealing rings using a thickness gauge.<br />
- If any measurements are greater than specified, replace the piston rings.<br />
N.B.<br />
BEFORE REPLACING ONLY THE PISTON RINGS, ENSURE THAT THE CLEARANCE BETWEEN<br />
THE PISTON RINGS AND THE PISTON RING GROOVES, AND BETWEEN THE PISTON AND THE<br />
CYLINDER, IS AS SPECIFIED. IN ANY CASE, NEW PISTON RINGS USED IN COMBINATION WITH<br />
A USED CYLINDER MAY HAVE DIFFERENT BEDDING CONDITIONS THAN THE STANDARD.<br />
SEALING RINGS<br />
Name Description Dimensions Initials Quantity<br />
Top piston ring 0.08 ÷ 0.20 mm 0.35 mm<br />
Middle piston ring 0.05 ÷ 0.20 mm 0.30 mm<br />
oil scraper 0.20 ÷ 0.70 mm 0.80 mm<br />
ENG - 89
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