PIAGGIO MSS X9 EVOLUTION 250 - Choosing the gasket

Choosing the gasket
- Provisionally fit the piston into the cylinder, without any base gasket.
- Assemble a dial gauge on the specific tool
- Set the dial gauge to zero placing the tool on a contrasting surface. Keeping the zero position, as-
semble the tool on the cylinder and lock it with 2 supplied nuts as shown in the figure.
- Rotate the crankshaft until TDC (the inverted point of the dial gauge rotation)
- Position the dial gauge on the piston as shown in the figure and measure how much the piston pro-
trudes.
- Identify the thickness of the cylinder base gasket to be used for reassembly by the table below. Cor-
rectly identify the cylinder base gasket thickness to keep the correct compression ratio.
- Remove the special tool and the cylinder.
N.B.
MEASUREMENT "A" TO BE TAKEN IS A VALUE OF PISTON RE-ENTRY, IT INDICATES BY HOW
MUCH THE PLANE FORMED BY THE PISTON CROWN FALLS BELOW THE PLANE FORMED BY
THE TOP OF THE CYLINDER. THE FURTHER THE PISTON FALLS INSIDE THE CYLINDER, THE
LESS THE BASE GASKET IS TO BE APPLIED (TO RECOVER THE COMPRESSION RATIO) AND
VICE VERSA.
Specific tooling
020428Y Piston position check support
ENGINE 250 SHIMMING
Name
Measure A Thickness
shimming 3.70 - 3.60 0.4 ± 0.05
shimming 3.60 - 3.40 0.6 ± 0.05
shimming 3.40 - 3.30 0.8 ± 0.05
MSS X9 Evolution 250 Engine
ENG - 115