Honda CB900F Service Manual page 197

CYLINDER HEAD/VALVES
Inst all a com pressi o n gauge in t o the spark plug ho le.
Disconnect the fuel pump/r eserve sensor 3P
connector.
CYLINDER COMPRESS ION TEST
07RMJ- MY50100
IEquivaient com-
mercially avail-
ab le)
TOOL :
Compression gauge attachment
Warm up the engine to normal operating
temperature.
Stop the engine and rem ove all di rect ignition
coil/spark plug caps and spark plugs (page 3-6) .
Open and su pport the front end of fue l tank
(page 3-4).
To avoid discharg-
ing the battery, do
not operate the
starter motor for
m ore than se ven
seconds.
Open the thro ttle all t he way and crank t he
eng ine w it h t he sta rt er motor until the gauge read ing
sto ps rising.
The ma ximu m read ing is usually reached w it hin 4 - 7
seconds.
Compression pressure:
1,275 kPa (13.0 kgf/cm', 185 psi ) al350 m in " (rpm)
Low comp ression can be caused by:
- Blow n cy linder head ga sket
- Im pro pe r v alv e adju stm ent
- Valve leakage
- Worn piston ring or cy linder
High comp ression ca n be cau sed by :
- Carbon deposits in combust ion cha m ber or on
piston hea d
CYLINDER HEA D COVER REM OVA L
Rem ove the following:
- Ignition coi l (page 5-62)
- Spark plu g cap (page 3-61
Remove the crankcase br eathe r tube.
Disconnect t he PA IR air su ctio n tubes fro m the PAIR
reed valve covers.
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