Yamaha FZR400 1988-1989 Service Manual page 110

COMPRESSION PRESSURE MEASUREMENT
(be sure the battery is fully charged) with the
throttle wide open until the compression
reading on the gauge stabilizes.
*Check readings with specified levels (See
chart).
Compression Gauge:
Compression Pressure (At sea level) :
Standard :
950 kPa (9.5 kg/cm2, 138 psi)
Minimum:
750 kPa (7.5 kg/cm2, 109 psi)
Maximum:
1,150 kPa (11.5 kg/cm*, 164 psi)
When cranking the engine, ground spark
plug lead to prevent sparking.
*Repeat the previous steps for the other
cylinders.
1) Squirt a few drops of oil into the affected
cylinder.
2) Measure the compression again.
Compression Pressure
(with oil introduced into cylinder)
Reading
Higher than
Worn or damaged pistons
VOTE:
The difference between the highest and lowest
nore than the specified value.
Difference Between Each Cylinder:
Less than 100 kPa (1 kg/cm*, 15 psi)
Diagnosis