Power Unit; Power Unit (Check And Adjustment); Checking The Compression Pressure; Checking The Oil Pressure - Yamaha F50D Servise Manual

POWR

Power unit

(check and adjustment)

Checking the compression pressure

1. Start the engine, and warm up for 5–10
minutes, and then turn it off.
2. Remove the clip from the engine shut-off
switch.
3. Remove the spark plug wires and all
spark plugs. NOTICE: Before removing
the spark plugs, remove any dirt or
dust in the spark plugs well that may
fall into the cylinders.
4. Install the special service tool 1 into a
spark plug hole.
Compression gauge 1: 90890-03160
5. Fully open the throttle.
6. Crank the engine until the reading on the
compression gauge stabilizes, and then
measure the compression pressure.
Minimum compression pressure
(reference data):
840.0 kPa (8.4 kgf/cm
TIP:
Make sure to use the fully charged battery
when measuring the compression pressure.
7. If the compression pressure is below
specification or the compression pres-
sure for each cylinder is unbalanced, add
a small amount of engine oil to the cylin-
der, and then measure the pressure
again.
7-1
Power unit
1
2
, 121.8 psi)
TIP:
9
If the compression pressure increases,
check the pistons and piston rings for wear.
9
If the compression pressure does not
increase, check the valve clearance, valve,
valve seat, cylinder head gasket and cylin-
der head.
8. Remove the special service tool 1.
9. Repeat the step 4–step 8 for each cylin-
der.

Checking the oil pressure

1. Disconnect the oil pressure switch lead
at the oil pressure switch end.
2. Remove the oil pressure switch, and then
install an oil pressure gauge 1 to the oil
pressure switch installation hole.
Oil pressure gauge 1:
Commercialy available
TIP:
9 Place a rag under the oil pressure switch.
9 Use a commercially available oil pressure
gauge 1.
3. Start the engine, and warm up until the
idle speed gets stable at specified engine
idle speed.
Engine idle speed:
F50D: 800–900 r/min
FT50C: 900–1000 r/min
4. Measure the oil pressure. Check for oil
leakage and also check the oil pump and
oil strainer if below specification.
1