Yamaha 1998 FZS600 5DM1-AE1, Service Manual

Page: 74 / 364

3-17
MEASURING THE COMPRESSION PRESSURE
CHK
ADJ
NOTE:
CAUTION:
EB303060
MEASURING THE COMPRESSION
PRESSURE
The following procedure applies to all of the cyl-
inders.
Insufficient compression pressure will result
in a loss of performance.
1. Check:
valve clearance
Out of specification
Adjust.
Refer to “ADJUSTING THE VALVE
CLEARANCE”.
2. Start the engine, warm it up for several min-
utes, and then turn it off.
3. Disconnect:
spark plug cap
4. Remove:
spark plug
Before removing the spark plugs, use
compressed air to blow away any dirt ac-
cumulated in the spark plug wells to pre-
vent it from falling into the cylinders.
5. Install:
compression gauge 1
Compression gauge
90890-03081
6. Measure:
compression pressure
Above the maximum pressure
Inspect
the cylinder head, valve surfaces, and pis-
ton crown for carbon deposits.
Below the minimum pressure
Squirt a
few measure again.
Refer to the following table.
Compression pressure
(with oil applied into the cylinder)
Reading Diagnosis
Higher than
without oil
Piston wear or
damage Repair.
Same as
without oil
Piston ring(-s),
valves cylinder
head gasket or
piston possibly
defective Repair.