Checking The Compression Pressure; Checking The Oil Pressure - Yamaha F100C Service Manual

POWR
21. Install the cover and flywheel magnet
cover.

Checking the compression pressure

1. Start the engine, warm it up for 5 min-
utes, and then turn it off.
2. Remove the clip from the engine shut-off
switch on the remote control box or tiller
handle.
3. Remove the cover and all spark plugs,
and then install the special service tools
to each spark plug hole.
CAUTION:
Before removing the spark plugs, well to
clear out any dirt or dust that may fall into
the cylinder.
Compression gauge 1:
90890-03160
Compression gauge adapter 2:
90890-06563
4. Fully open the throttle, crank the engine
until the reading on the compression
gauge stabilizes, and then check the
compression pressure.
Minimum compression pressure:
670 kPa (6.7 kgf/cm
5-9
Power unit
S60C5040
2
, 95.3 psi)
5. If the compression pressure is below
specification and the compression pres-
sure for each cylinder is unbalanced, add
a small amount of engine oil to the cylin-
der, and then check the pressure again.
NOTE:
• If the compression pressure increases,
check the piston and piston rings for wear.
Replace if necessary.
• If the compression pressure does not
increase, check the valve clearance, valve,
valve seat, cylinder sleeve, cylinder head
gasket, and cylinder head. Adjust or
replace if necessary.

Checking the oil pressure

1. Start the engine, warm it up for 5 min-
utes, and then turn it off.
2. Remove the flywheel magnet cover and
oil pressure switch, and then install an oil
pressure gauge 1 to the oil pressure
switch installation hole.
NOTE:
Use a pressure gauge with an adapter that
has a 1/8 pitch thread.
3. Check the oil pressure. Check the oil
pump, oil suction pipe, and oil strainer if
out of specification.
Oil pressure:
520 kPa (5.2 kgf/cm
idle speed (850 r/min)
2
, 74 psi) at
60C5D11