Power Unit; Checking The Compression Pressure; Checking The Oil Pressure - Yamaha F50F Service Manual

POWR

Power unit

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 stop
lanyard switch.
3. Remove the spark plug caps and all
spark plugs, and then install the special
service tools into a spark plug hole.
CAUTION:
Before removing the spark plugs, blow
compressed air in the spark plug well to
clear out any dirt or dust that may fall into
the cylinder.
Compression gauge 1:
90890-03160
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
(reference data):
960 kPa (9.6 kgf/cm
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.
5-3
Power unit
2
, 139.2 psi)
5
NOTE:
• If the compression pressure increases,
check the pistons and piston rings for wear.
Replace if necessary.
• If the compression pressure does not
increase,
valves, valve seat, cylinder sleeve, cylinder
head gasket, and cylinder head. Adjust or
replace if necessary.

Checking the oil pressure

1. Place a rag under the oil pressure switch.
2. Remove the oil pressure switch, and then
install an oil pressure gauge 1 into the
oil pressure switch installation hole.
NOTE:
Use a general pressure gauge.
3. Start the engine and warm it up for 5 min-
utes.
4. Check the oil pressure. Check the oil
pump and oil strainer and check for oil
leakage if below specification.
Oil pressure (reference data):
125 kPa (1.25 kgf/cm
at engine idle speed
5. Increase the engine speed, and then
check the relief valve opening pressure.
NOTE:
The relief valve is installed in the oil pump.
check the valve
2
, 18.1 psi)
clearance,
6C13G11