Yamaha F50 Service Manual

							62Y3A115-24
1
2
3
4
5
6
7
8
I
No. Part name Q’ty RemarksTightening torques
Stage N·mkgf·mft·lb
1 Throttle link rod 1
2 Throttle cam 1
3 Throttle control lever 1
4 Clip 1
5 Bushing 1
6Bolt 1 M6 ×
 20 mm
7Spring 1
8Collar 1
9Bracket 1
10 Bolt 1 M6 ×
 30 mm
11 Shift rod 1
12 Bolt 1 M6 ×
 30 mm
13 Bracket 1
14 Spring 1
15 Bolt 1
Power unit 
						

							POWRPower unit
5-2562Y3A11
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 all spark plugs, and then
install the special service tool to each
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.
4. Fully open the throttle, crank the engine
until the reading on the compression
gauge stabilizes, and then check the
compression pressure.
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 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 with a
1/8 pitch thread.
3. Check the oil pressure. Check the oil
pump, oil suction pipe, and oil strainer if
out of specification. Compression gauge 1
:
YU-33223-1 / 90890-03160
Minimum compression pressure:
840 kPa (8.4 kgf/cm
2, 122 psi)Oil pressure:
100 kPa (1.0 kgf/cm
2, 14 psi) at idle 
speed (900 ±
 50 r/min) 
						

							62Y3A115-26
1
2
3
4
5
6
7
8
I
Removing the power unit
1. Remove the flywheel magnet cover and
flywheel magnet.
ÈFor USA and Canada
ÉFor worldwide
CAUTION:
•Apply force in the direction of the
arrows shown, to prevent the flywheel
holder from slipping off easily.
•To prevent damage to the engine or
tools, screw in the flywheel puller set
bolts evenly and completely so that the
flywheel puller plate is parallel to the fly-
wheel magnet.
NOTE:
Apply force to the crankshaft end until the fly-
wheel magnet comes off the tapered portion
of the crankshaft.
Flywheel magnet holder 1
: YB-06139
Flywheel holder 1
: 90890-06522
Universal puller 2
: YB-06117
Flywheel puller 2
: 90890-06521
Power unit 
						

							POWRPower unit
5-2762Y3A11
2. Disconnect the throttle cable 1
 and shift
cable/shift rod 2
.
3. Disconnect the fuel hose 3
 and throttle
link rod 4
.
4. Disconnect the battery leads 5
, 10-pin
coupler 6
, PTT relay leads 7
 (EHT,
ET), PTT motor leads 8
 (EHT, ET),
ground lead 9
 (EHT, ET), warning indi-
cator coupler 0
 (EHD, EHT), trailer
switch coupler A
 (EHT, ET), pilot water
hose B
, and flushing hose (models with
flushing device).5. Remove the power trim and tilt relay C
,
shift rod D
 and shift rod bolts E
.
6. Remove the apron F
. 
						

							62Y3A115-28
1
2
3
4
5
6
7
8
I
7. Remove the power unit by removing the
bolts G
.
Power unit 
						

							POWRPower unit
5-2962Y3A11
Timing belt and sprockets5 
						

							62Y3A115-30
1
2
3
4
5
6
7
8
I
No. Part name Q’ty RemarksTightening torques
Stage N·mkgf·mft·lb
1 Timing belt 1
2 Drive sprocket 1
3 Driven sprocket 1
4 Bolt 1 8 0.8 5.8
5Bolt 1 M8 ×
 20 mm 25 2.5 18
6 Tensioner 1
7Spring 1
8 Nut 1 140 14 101
9 Retaining plate 2
10 Woodruff key 1
11 Bolt 1 M10 ×
 40 mm 38 3.8 28
12 Washer 1
13 Bolt 2 M6 ×
 20 mm
14 Blowby hose 1
15 Clip 1
16 Dowel pin 1
Timing belt and sprockets 
						

							POWRPower unit
5-3162Y3A11
Removing the timing belt and 
sprockets
1. Set the cylinder #1 piston position to
TDC of the compression stroke by align-
ing the “1” mark a
 on the driven sprocket
with the “” mark b
 on the cylinder
head.
CAUTION:
Do not turn the drive sprocket counter-
clockwise, otherwise the valve system
may be damaged.
2. Remove the breather hose and loosen
the drive sprocket nut 1
.
NOTE:
Use a deep socket 2
 (M42) for this proce-
dure.
Do not turn the camshaft when loosening
the drive sprocket nut.3. Remove the tensioner 4
 and timing belt
5
 from the driven sprocket side.
4. Loosen the driven sprocket bolt 6
 and
remove the driven sprocket 7
.
ÈFor USA and Canada
ÉFor worldwide
NOTE:
Do not turn the camshaft when loosening the
driven sprocket bolt.
Crankshaft holder 3
: YB-06562
Crankshaft holder 18 3
: 90890-06562
Flywheel magnet holder: YB-06139
Flywheel holder: 90890-06522 
						

							62Y3A115-32
1
2
3
4
5
6
7
8
I
5. Remove the nut 1
, retaining plates 8
,
drive sprocket 9
, and Woodruff key 0
.
Checking the timing belt and 
sprockets
1. Check the interior and exterior of the tim-
ing belt for cracks, damage, or wear.
Replace if necessary.
2. Check the drive sprocket 1
 and driven
sprocket 2
 for cracks, damage, or wear.
Replace if necessary.
Installing the timing belt and 
sprockets
1. Check that the “1” mark a
 on the driven
sprocket 1
 is aligned with the “” mark
b
 on the cylinder head, and then tighten
the bolt 2
.
2. Install the retaining plate 3
, Woodruff
key 4
, drive sprocket 5
, retaining plate
3
, and nut 6
, and then tighten the nut.
S62Y5170
12
Timing belt and sprockets 
						

							POWRPower unit
5-3362Y3A11
3. Check that the “” mark c
 on the retain-
ing plate is aligned with the “” mark d
on the cylinder body.
4. Install the new timing belt 7
 from the
drive sprocket side with its part number
in the upright position.
CAUTION:
•Do not twist, turn inside out, or bend the
timing belt beyond the maximum limit of
25 mm (1.0 in) e
, otherwise it may be
damaged.
•Do not get oil or grease on the timing
belt.5. Install the tensioner 8
 and bolts, and
then tighten the bolts finger tight.
6. Take up the timing belt slack by turning
the drive sprocket clockwise at least two
full turns.
CAUTION:
Do not turn the sprockets counterclock-
wise, otherwise the valve system may be
damaged.
7. Tighten the tensioner bolts to the speci-
fied torque.
8. Turn the drive sprocket two turns, and
then check that the alignment marks are
aligned.
Tensioner bolt 9
:
8 N·m (0.8 kgf·m, 5.8 ft·lb)
Tensioner bolt (adjusting bolt) 0
:
25 N·m (2.5 kgf·m, 18 ft·lb)
S62Y5216
0
9