PIAGGIO MSS ZIP 100 4T, Service Manual

Page: 90 / 192

Inspecting the small end
- Measure the internal diameter of the small end
using an internal micrometer.
N.B.
IF THE DIAMETER OF THE ROD SMALL END EXCEEDS
THE MAXIMUM DIAMETER ALLOWED, SHOWS SIGNS OF
WEAR OR OVERHEATING REPLACE THE CRANKSHAFT
AS DESCRIBED IN THE "CRANKCASE AND CRANK-
SHAFT" CHAPTER".
Characteristic
Max. diameter admitted: check the small end
13.030 mm
Standard diameter: check the small end
13 +0.025+0.015mm
Inspecting the wrist pin
- Measure the outer diameter of the gudgeon pin.
Characteristic
Standard diameter: gudgeon pin
13 -0-0.004mm
Minimum admissible diameter gudgeon pin
12.990 mm
Inspecting the piston
- Carefully clean the sealing rings housings with the aid of an old piston ring.
- 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.
PISTON
Name Description Dimensions Initials Quantity
Top piston ring 0.030 ÷ 0.065 mm 0.080 mm
Middle piston ring 0.020 ÷ 0.055 mm 0.070 mm
oil scraper 0.040 ÷ 0.160 mm 0.20 mm
Engine
MSS ZIP 100 4T
ENG - 90