Yamaha TZ250M1 Owner's Service Manual page 274

SETTING
NOTE:
• Finish the break-in before changing the gas-
ket.
• A change of 0.1 mm (0.004 in) for the gasket
causes a change of approximately 0.23 cm
(0.008 lmp oz, 0.008 US oz) of the combus-
tion chamber volume.
• After break-in, change to an appropriate gas-
ket to allow the piston protrusion to be -0.15
mm (-0.006 in) to 0.05 mm (0.002 in).
C C CAUTION:
• Piston protruding amount must be a max-
imum 0.15 mm (0.006 in). Above this value,
the piston and cylinder head may contact
each other.
• Too much random piston protrusion at low
temperature may develop an abnormal
combustion (detonation), which may
adversely affect the intended performance
of the engine.
A Air temperature
B Piston protruding amount
EC71T000
Cylinder gasket setting parts
Part number
4JT-11351-02
4JT-11351-12
4JT-11351-22
4DP-11351-31
4DP-11351-40
* Factory installed
EC71L002
Measuring piston protrusion
1. Install the dial gauge 1 and dial gauge
stand 2 to the cylinder contact surface and
set the scale of the dial gauge to zero.
C
Dial gauge:
YU-03097/90890-01252
Stand:
YU-01256
7-10
TUN
Size (thickness)
* t=0.8 mm (0.031 in)
t=0.7 mm (0.028 in)
t=0.6 mm (0.024 in)
t=0.5 mm (0.020 in)
t=0.4 mm (0.016 in)
3