Yamaha F50 Service Manual

							62Y3A114-12
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No. Part name Q’ty RemarksTightening torques
Stage N·mkgf·mft·lb
1 Carburetor assembly 1 Joint-to-silencer
2 Clip 1
3 Blowby hose 1
4 Prime Start coupler 1
5Bolt 2 M6 ×
 30 mm
6Collar 2
7 Throttle link rod 1
8 O-ring 8
Not reusable
9 Insulator 1
10 Dowel pin 2
11 Bolt 8 M6 ×
 25 mm
12 Fuel hose 2 Fuel pump-to-carburetor
13 Clip 2
14 Rivet 2
Carburetor unit 
						

							FUELFuel system
4-1362Y3A11 
						

							62Y3A114-14
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No. Part name Q’ty RemarksTightening torques
Stage N·mkgf·mft·lb
1 Acceleration pump 1
2 Screw 3 M5 ×
 9 mm
3Link rod 1
4 Hose 1 Acceleration pump-to-
acceleration pump
5 Hose 4 Acceleration pump-to-
carburetor
6Link rod 1
Carburetor unit 
						

							FUELFuel system
4-1562Y3A11 
						

							62Y3A114-16
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No. Part name Q’ty RemarksTightening torques
Stage N·mkgf·mft·lb
1 Carburetor 4
2 Silencer 1
3 Plastic tie 1
Not reusable
4 Blowby hose 1 Silencer-to-joint
5Bolt 8 M6 ×
 90 mm
6Collar 8
7 O-ring 4
Not reusable
8Plate 1
9 O-ring 4
Not reusable
10 O-ring 4Not reusable
11 Joint 1
12 Plastic tie 7
Not reusable
13 Fuel hose 4 Carburetor-to-carburetor
14 Fuel hose 2 Carburetor-to-fuel pump
Carburetor unit 
						

							FUELFuel system
4-1762Y3A11
Carburetor4 
						

							62Y3A114-18
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È
 Carburetors #1, #2, and #3
É
 Carburetor #4
Ê
 Carburetors #1 and #3 No. Part name Q’ty RemarksTightening torques
Stage N·mkgf·mft·lb
1 Carburetor body 1
2 Screw 4 M4 ×
 13 mm
3 Cover 1
4 Seal 1
Not reusable
5 Pilot jet 1
6Main jet 1
7 Needle valve 1
8 Main nozzle 1
9 O-ring 1
Not reusable
10 Plug 1
11 Float 1
12 Screw 1 M4 ×
 6 mm
13 Float pin 1
14 Gasket 1
Not reusable
15 Float chamber 1
16 Drain screw 1
17 O-ring 1
Not reusable
18 Screw 4 M4 ×
 13 mm
19 Fuel hose 1 Float chamber-to-body
20 Prime Start 1
21 Screw 1 M4 ×
 7 mm
22 O-ring 1
Not reusable
23 Bracket 1
24 Body 1
25 Screw 2 Carburetor #1: M4 ×
 17 mm
Carburetor #3: M4 ×
 22 mm
26 Gasket 1
Not reusable
27 Spring 1
28 O-ring 1
Not reusable
29 Pilot screw 1
Carburetor 
						

							FUELFuel system
4-1962Y3A11
Checking the carburetor
1. Check the air and fuel passages and jets,
for dirt and foreign matter. Clean the car-
buretor body with a petroleum based sol-
vent if necessary.
2. Blow compressed air into all passages
and jets.
CAUTION:
•Direct the compressed air downward,
otherwise cleaning solvent may be
blown into your eyes or small parts of
the carburetor may be blown off.
•Do not use steel wire for cleaning the
jets, otherwise the jet diameters may be
enlarged, which may seriously affect
performance.
3. Check the main jet 1
, pilot jet 2
, and
main nozzle 3
 for dirt or residue. Clean if
necessary.
4. Check the pilot screw and needle valve
for bends or wear. Replace if necessary.
S62Y4230
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							62Y3A114-20
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5. Check the float for deterioration. Replace
it necessary.
6. Measure the float height a
. Replace the
float and needle valve, if out of specifica-
tion, as a set.
NOTE:
The float should be resting on the needle
valve 4
, but not compressing it.
Take measurements at the top of the float
flange opposite its pivoted side.
Checking the Prime Start
1. Measure the length of the Prime Start
plunger.
2. Connect the positive Prime Start blue (L)
lead and the negative Prime Start black
(B) lead to a battery as shown.
3. Measure the plunger length a
 after
applying power for 5 minutes. Replace if
out of specification.
Assembling the carburetor
1. Install the main nozzle 1
, plug 2
, pilot
jet 3
, and main jet 4
 to the carburetor
body as shown.
Float height a
:
10.0 ±
 0.5 mm (0.39 ±
 0.02 in)
Prime Start plunger extended length a
:
24.6 mm (0.97 in)
S62Y4270
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32
1
Carburetor 
						

							FUELFuel system
4-2162Y3A11
2. Install the needle valve 5
, float 6
, float
pin 7
, and screw 8
 as shown, and then
the check the float for smooth operation.
NOTE:
Place the needle valve in the valve seat
when installing the float to the carburetor
body.
Fit the float pin into the slit on the carbure-
tor body and lock it with the screw.
3. Install the pilot screw 9
, turn it in until it
is lightly seated, then out the specified
number of turns.
Adjusting the throttle link rod
1. Push the throttle control lever 1
 to the
fully open position as shown, and then
measure the gap between the carburetor
throttle lever 2
 and carburetor stopper
3
.
2. If out of specification, adjust the throttle
link rod length.
3. Remove the throttle link rod 4
, adjust it
to the specified length b
, and then install
it.
Pilot screw setting:
Carburetors #1, #2, and #3:
2 1/4 ±
 1/2 turns out
Carburetor #4: 2 1/2 ±
 1/2 turns out
S62Y4280
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8 6
Gap a: Less than 0.5 mm (0.02 in)
Throttle link rod length b:
144 mm (5.67 in)