Yamaha F50 Service Manual

62Y3A115-4
1
2
3
4
5
6
7
8
I
Symptom: Engine can be started, but does not remain on.
Check the fuel system.
Check the ignition system.
Check the compression pressure of power unit.
Is the vent 
screw open?
Water or resi-
due?
Good operat-
ing condition?
Kinks or fuel 
leakage?
Replace the pri-
mary fuel pump.
Check for water or residue in 
the fuel filter.
Open the fuel vent screw.
Replace the respective parts.
Clean the fuel system from the 
fuel tank to the fuel filter.
Check the fuel hose for kinks...

POWRPower unit
5-562Y3A11
Is there air 
intake?Replace the respective seals.
Check the compression pres-
sure of the combustion chamber.
No
Yes
Check that there is no secondary air intake on the contact surfaces of 
the intake manifold and crankcase.
Check the ignition spark gap using the spark gap tester.
Out of specifi-
cation?
Replace the spark plug.
Check the ignition system out-
put peak voltage.
Yes
No 

62Y3A115-6
1
2
3
4
5
6
7
8
I
Symptom: The engine idle speed is not steady, but increases or decreases.
Check the carburetors.
Check the air intake system.
Check the ignition system.
Replace the CDI unit.
Check and disassemble the car-
buretors, and then clean them if 
necessary.
Check the throttle cable opera-
tion and lubricate it if necessary.
Out of specifi-
cation?
Do the valves 
close simul-
taneously?
Do the valves 
close simul-
taneously?
Check the second-
ary air intake on the 
O-ring and...

POWRPower unit
5-762Y3A11
Symptom: Engine does not accelerate when the throttle is opened quickly.
The engine turns off when the throttle is opened quickly.
Acceleration is tardy and the engine is likely to stop at any moment.
Check the carburetors.
Check the ignition system.
Check the compression pressure of power unit.
Check the needle valve of the 
carburetor for debris or wear.
Adjust the throttle cable.
Check each jet of the carburetor 
for clogs or debris.
Clean or replace the respective...

62Y3A115-8
1
2
3
4
5
6
7
8
I
Symptom: Engine can run, but engine speed will not increase.
Overheat warning indicator is on.
Oil pressure warning indicator is on.
Warning indicator is on and buzzer is sounding.
Check the water cooling system.
Check the lubricating system.
Check the water inlet for clogs 
or debris.
Check the thermoswitch.
Check that cooling water is dis-
charged from the pilot water 
outlet.
Replace the thermostat.
Replace the CDI unit.
Replace the thermoswitch.
Check the water 
pump...

POWRPower unit
5-962Y3A11
Check the oil pump for debris or 
wear.
Check the engine oil level.
Check the oil pressure.
Check the oil pressure switch.Clean or replace the respective 
parts.
At specified 
level?
Out of specifi-
cation?
Good condi-
tion?
Debris or 
wear?Check the oil pas-
sage.
Yes
No
Yes
No
Yes
Yes
No
No
Add engine oil to the correct 
level.
Replace the oil pressure switch.
Replace the CDI unit. 

62Y3A115-10
1
2
3
4
5
6
7
8
I
Special service tools5
Compression gauge
YU-33223-1
Flywheel magnet holder
YB-06139
Universal puller
YB-06117
Crankshaft holder
YB-06562
Valve spring compressor
YM-01253Valve guide remover
YM-01122
Valve guide reamer
YM-01196
Valve seat cutter set
YM-91043-C
Drive shaft needle bearing depth stop
YB-34473
Oil filter wrench
YU-38411
For USA and Canada
Special service tools 

POWRPower unit
5-1162Y3A11
Piston ring compressor
YU-33294
Compression gauge
90890-03160
Flywheel holder
90890-06522
Flywheel puller
90890-06521
Crankshaft holder 18
90890-06562Valve spring compressor
90890-04019
Valve spring compressor attachment
90890-06320
Valve guide remover/installer
90890-06801
Valve guide reamer
90890-06804
Valve seat cutter holder
90890-06316
For worldwide 

62Y3A115-12
1
2
3
4
5
6
7
8
I
Valve seat cutter
90890-06315, 90890-06323, 90890-06326, 
90890-06328, 90890-06555
Bearing outer race attachment
90890-06626
Oil filter wrench
90890-01426
Piston slider
90890-06529
Special service tools 

POWRPower unit
5-1362Y3A11
Power unit5