PIAGGIO Beverly 250 USA Workshop Manual page 144

Engine
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.
Name
shimming
shimming
shimming
ENG - 40
SHIMMING
Measure A
3.70 - 3.60
3.60 - 3.40
3.40 - 3.30
Beverly 250 USA
Thickness
0.4 ± 0.05
0.6 ± 0.05
0.8 ± 0.05