Yamaha YFM90RA Model Vehicle User Manual


 
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CHK
ADJ
MEASURING THE COMPRESSION PRESSURE
EBS00061
MEASURING THE COMPRESSION
PRESSURE
TIP
Insufficient compression pressure will result in
a loss of performance.
1. Measure:
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
NOTICE
Before removing a spark plug, use com-
pressed air to blow away any dirt accumu-
lated in the spark plug well to prevent it
from falling into the cylinder.
5. Attach:
compression gauge
6. Measure:
compression pressure
Out of specification
Refer to steps (c)
and (d).
Compression pressure (at sea
level)
Minimum
1,050 kPa/1,000 r/min
(10.5 kg/cm
2
, 152.3 psi)
Standard
1,250 kPa/1,000 r/min
(12.5 kg/cm
2
, 181.3 psi)
Maximum
1,350 kPa/1,000 r/min
(13.5 kg/cm
2
, 195.8psi)
Compression gauge
90890-03081
Extension
90890-04082
YU-33223