Specifications

3
43
ASSEMBLING AND TESTING THE ENGINE
3.11
3.11.1
THERMAL UNIT
Before assembling the thermal unit you
must perform thorough verifications on the
cylinder, piston, piston pin, piston rings and
head as described below.
TESTING THE PISTON, PISTON
PIN AND PISTON RINGS
Remove the carbon deposits from the piston
crown and wash the entire plunger with a
special degreasing product. Do not use poin-
ted or sharp tools for the cleaning process.
Then carefully analyse the piston, which must
have no strains, scratches, cracks or any kind
of damage.
Then analyse the external diameter of the
plunger - the limit of service is given in the
table below, relative to the specific category.
The diameter must be measured at X from
the bottom of the mantle, perpendicular to
the axis of the piston pin.
The category is marked on the piston
crown.
Verify the size of the piston pin and its hou-
sing found on the piston. The piston pin
must be measured from its extreme ends,
which engage with the piston.
Height at which the external diameter of the piston
is measured.
Measuring the piston pin and its housing.
X
Cubic Capacity
[cm³]
Height X
[mm]
Limit of service according to the category
A B C D
125 11.5 53.935 53.945 53.955
200 12 63.935 63.945 63.955 63.965
250 13.5 72.445 72.455 72.465
290 16 77.950 77.960 77.970
Cubic
Capacity
[cm³]
Size limit [mm]
Piston pin
housing
Piston pin
125-200 16.02 15.99
250 - 290 18.02 17.99