Compression Pressure Measurement - Yamaha CE50T Service Manual

INSP
COMPRESSION PRESSURE MEASUREMENT
ADJ
• ;!i ...... COMPRESSION PRESSURE
Insufficient compression pressure will result in
performance loss and may indicate worn or
__4 A damaged piston rings.
1. Remove:
®Cover (_
2. Warm up engine for serveral minutes, then
stop the engine.
........ _ 3. Remove:
I eSpark plugs
4. Connect:
®Compression Gauge (YU-33223) (_
_..._:_::,. 5. Measure:
_ "" :::: :::: ........ • Co mpression
NOTE:
Start the starter motor and throttle valve wide-
open until the pressure indicated on gauge can
rise no further. Compression should be within the
specified levels.
Compression Pressure (at sea level):
Standard ....... 800 kPa (8.0 kg/cm 2,
114 psi)
Minimum ...... 640 kPa (6.4 kg/cm 2,
91 psi)
When cranking engine, ground spark plug
wires to prevent sparking.
Compression test steps (below minimum
levels):
oSquirt a few drops of oil into cylinder.
eMeasure compression again.
Reading Diagnosis
®Worn cylinder,
Higher than piston and piston
without oil
rings
®Defective piston,
Same as ring(s), valve(s) and
without oil
cylinder head gasket
Compression test steps (above standard
levels):
eCheck cylinder head or piston crown for car-
bon deposits.
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