TM RACING 250 EN, Workshop Manual

Page: 31 / 72

27
2
2
3
5
5
4
3
6
7
1
A
C
B
ENGINE DISASSEMBLY
Fit the new gaskets (2) on the upper part of the cylinder (3).
Mount the head (4) on the cylinder (3) and screw the screws (5) without
tightening then tighten them crosswise with a torque of 20 Nm (2,0 kgm,
14,75 ft/lb).
remove the cap (A) from the generator cover (B).
Check the condition of the gasket (C), if damaged, replace.
Using a socket wrench (6), alternately move the piston, passing repeatedly
to the TDC until the resistance of the tin is no longer felt.
Undo the screws (5) and remove the head (4).
Take the piece of tin (1) from the piston and measure the thickness (squish)
which must be between 1,6÷1,7 mm (0,63
÷ 0,67 in)
.
NOTE: If the measured measurement is not within the established meas-
urement, the base gasket (7) of the cylinder must be replaced
with one of a thickness suitable for the detected measurement.
For example:
- if the measured measurement is greater than 1,7
mm (0.67 in) it will be necessary to insert a gasket
(7) with a thickness greater than the one fitted;
- if the measured measurement is less than 1,6 mm
(0,63 in) it will be necessary to insert a gasket (7)
with a lower thickness than the one installed.
For the gasket replacement operations, refer to the previous paragraphs.
Repeat the squish check operation to verify that it is within the established
size.
Refit the cap (A).