PIAGGIO MP3 400 i.e. - Inspecting the Small End; Inspecting the Wrist Pin

- Remove the 2 piston pin locking rings by the spe-
cific housings.
- Extract the pin and remove the piston.
N.B.
USE PAPER OR A CLOTH TO CLOSE THE CYL-
INDER HOUSING MOUTH ON THE CRANK-
CASE TO PREVENT SLIPPAGE OF ONE OF
THE PIN LOCKING RINGS INTO THE CASE.
- Remove the piston sealing rings and the oil scra-
per.
CAUTION
NOTE THE ASSEMBLY POSITIONS OF THE
LININGS TO PREVENT INVERTING THE POSI-
TION IN CASE OF REUSE.
N.B.
BE CAREFUL NOT TO DAMAGE THE SEALING
RINGS DURING REMOVAL.
Inspecting the small end
- Using a bore gauge, measure the connecting rod
small end diameter.
N.B.
IF THE CONNECTING ROD SMALL END DIAM-
ETER EXCEEDS THE STANDARD DIAMETER,
EXHIBITS WEAR OR OVERHEATING, PRO-
CEED TO REPLACE THE CRANKSHAFT AS
DESCRIBED IN CHAPTER CRANKCASE AND
CRANKSHAFT.
Characteristic
Standard diameter:
22 + 0.025 +0.015 mm
Inspecting the wrist pin
- Check the pin outside diameter using a micrometer.
Characteristic
Standard diameter:
22 0 - -0.004 mm
MP3 400 i.e. Engine
ENG - 55