Yamaha YFM45FAR, YFM450FAR. Service Manual

3 - 7

CHK

ADJ

SEAT, CARRIERS, FENDERS AND FUEL TANK

Order

Job name/Part name

Q’ty

Remarks

CDI unit

Wire harness

Rear fender

For installation, reverse the removal
procedure.

3 - 8

CHK

ADJ

SEAT, CARRIERS, FENDERS AND FUEL TANK

FUEL TANK

Order

Job name/Part name

Q’ty

Remarks

Removing the fuel tank

Remove the parts in the order below.

Seat and fuel tank side panels

Refer to “SEAT AND SIDE PANELS”.

Fuel tank cover

Refer to “FRONT CARRIER, FRONT
BUMPER AND FRONT FENDER”.

Fuel hose

NOTE:

Before disconnecting the fuel hose, turn
the fuel cock to “OFF”.

Fuel cock lever

Fuel tank

NOTE:

When installing the fuel tank, pass the
fuel tank breather hose through the hole
of the handlebar protector.

Float chamber air vent hose

Plastic band

Rubber cover

For installation, reverse the removal
procedure.

3 - 9

CHK

ADJ

FOOTREST BOARDS

Order

Job name/Part name

Q’ty

Remarks

Removing the footrest boards

Remove the parts in the order below.

Fuel tank side panels

Refer to “SEAT AND SIDE PANELS”.

Left footrest board

Right footrest board

Footrest bracket

For installation, reverse the removal
procedure.

3 - 10

CHK

ADJ

ADJUSTING THE VALVE CLEARANCE

ENGINE

ADJUSTING THE VALVE CLEARANCE

NOTE:

●

The valve clearance must be adjusted when
the engine is cool to the touch.

●

Adjust the valve clearance when the piston is
at the Top Dead Center (T.D.C.) on the
compression stroke.

1.Remove:

●

Seat

●

Front carrier

●

Front fender

●

Fuel tank
Refer to “SEAT, CARRIERS, FENDERS
AND FUEL TANK”.

2.Remove:

●

Tappet cover (intake)

●

Tappet cover (exhaust)

3.Disconnect:

●

Spark plug cap

4.Remove:

●

Spark plug

5.Remove:

●

Recoil starter

6.Remove:

●

Timing plug

3 - 11

CHK

ADJ

ADJUSTING THE VALVE CLEARANCE

7.Check:

●

Valve clearance
Out of specification

→

Adjust.

*****************************************************

Checking steps:

●

Turn the crankshaft counterclockwise with a
wrench.

●

Align the “T” mark

on the rotor with the

stationary pointer

on the crankcase cover.

When the “T” mark is aligned with the
stationary pointer, the piston is at the Top
Dead Center (T.D.C.).

NOTE:

●

When the piston is at the Top Dead Center
(T.D.C.) on the compression stroke, there
should be clearance between the valve stem
tips and their respective rocker arm adjusting
screws.

●

If there is no clearance, rotate the crankshaft
counterclockwise one turn.

●

Measure the valve clearance using a feeler
gauge

*****************************************************

Valve clearance (cold):

Intake:

0.06 ~ 0.10 mm
(0.0024 ~ 0.0039 in)

Exhaust:

0.16 ~ 0.20 mm
(0.0063 ~ 0.0079 in)

3 - 12

CHK

ADJ

ADJUSTING THE VALVE CLEARANCE

8.Adjust:

●

Valve clearance

*****************************************************

Adjustment steps:

●

Loosen the locknut

●

Insert a feeler gauge

between the adjuster

end and the valve end.

●

Turn the adjuster

clockwise or

counterclockwise with the valve adjusting
tool

until the proper clearance is obtained.

●

Hold the adjuster to prevent it from moving
and then tighten the locknut.

●

Measure the valve clearance.

●

If the clearance is incorrect, repeat the above
steps until the proper clearance is obtained.

*****************************************************

Tappet adjusting tool:

P/N. YM-08035, 90890-01311

Locknut:

20 Nm (2.0 m • kg, 14 ft • lb)

9.Install:

●

All removed parts

NOTE:

Install all removed parts in the reverse order of
their disassembly. Note the following points.

10.Install:

●

Recoil starter

●

Spark plug

●

Tappet covers

NOTE:

Install the tappet covers with the ridge facing
up

10 Nm (1.0 m • kg, 7.2 ft • lb)

18 Nm (1.8 m • kg, 13 ft • lb)

10 Nm (1.0 m • kg, 7.2 ft • lb)

3 - 13

CHK

ADJ

ADJUSTING THE VALVE CLEARANCE/

ADJUSTING THE IDLING SPEED

11.Install:

●

Fuel tank

●

Front fender

●

Front carrier

●

Seat
Refer to “SEAT, CARRIERS, FENDERS
AND FUEL TANK”.

ADJUSTING THE IDLING SPEED

1.Start the engine and let it warm up for

several minutes.

2.Remove:

●

Seat

●

Fuel tank side panels
Refer to “SEAT, CARRIERS, FENDERS
AND FUEL TANK”.

3.Attach:

●

Inductive tachometer or engine tachometer
(to the spark plug lead)

4.Check:

●

Engine idling speed
Out of specification

→

Adjust.

Inductive tachometer:

P/N. YU-8036-A

Engine tachometer:

P/N. 90890-03113

Engine idling speed:

1,450 ~ 1,550 r/min

3 - 14

CHK

ADJ

ADJUSTING THE IDLING SPEED/

ADJUSTING THE THROTTLE LEVER FREE PLAY

5.Adjust:

●

Engine idling speed

*****************************************************

Adjustment steps:

●

Turn the throttle stop screw

in or out until

the specified idling speed is obtained.

*****************************************************
6.Detach:

●

Inductive or engine tachometer

7.Adjust:

●

Throttle lever free play
Refer to “ADJUSTING THE THROTTLE
LEVER FREE PLAY”.

8.Install:

●

Fuel tank side panels

●

Seat
Refer to “SEAT, CARRIERS, FENDERS
AND FUEL TANK”.

Turning in

Idling speed becomes
higher.

Turning out

Idling speed becomes
lower.

Throttle lever free play:

3 ~ 5 mm (0.12 ~ 0.20 in)

ADJUSTING THE THROTTLE LEVER FREE
PLAY

NOTE:

Engine idling speed should be adjusted
properly before adjusting the throttle lever free
play.

3 - 15

CHK

ADJ

ADJUSTING THE THROTTLE LEVER FREE PLAY

1.Check:

●

Throttle lever free play

Out of specification

→

Adjust.

Throttle lever free play:

3 ~ 5 mm (0.12 ~ 0.20 in)

2.Remove:

●

Seat

●

Fuel tank side panel (right)
Refer to “SEAT, CARRIERS, FENDERS
AND FUEL TANK”.

3.Adjust:

●

Throttle lever free play

*****************************************************

Adjustment steps:
First step:

●

Pull back the adjuster cover

●

Loosen the locknut

on the carburetor side.

●

Turn the adjuster

in or out until the correct

free play is obtained.

●

Tighten the locknut

●

Push in the adjuster cover

NOTE:

If the free play cannot be adjusted here, adjust
it at the throttle lever side of the cable.

Turning in

Free play is increased.

Turning out Free play is decreased.

3 - 16

CHK

ADJ

ADJUSTING THE THROTTLE LEVER FREE PLAY/

ADJUSTING THE SPEED LIMITER

Second step:

●

Pull back the adjuster cover

●

Loosen the locknut

●

Turn the adjuster

in or out until the correct

free play is obtained.

●

Tighten the locknut

●

Push in the adjuster cover

WARNING

After adjusting the free play, turn the
handlebar to the right and left to make sure
that the engine idling speed does not
increase.

*****************************************************

Turning in

Free play is increased.

Turning out Free play is decreased.

4.Install:

●

Fuel tank side panel (right)

●

Seat
Refer to “SEAT, CARRIERS, FENDERS
AND FUEL TANK”.

ADJUSTING THE SPEED LIMITER

The speed limiter keeps the carburetor throttle
from becoming fully-opened even when the
throttle lever is applied to the maximum
position. Screwing in the adjuster stops the
engine speed from increasing.

1.Check:

●

Speed limiter length

Out of specification

→

Adjust.

Speed limiter length:

12 mm (0.47 in)

3 - 17

CHK

ADJ

ADJUSTING THE SPEED LIMITER/

ADJUSTING THE STARTER CABLE

2.Adjust:

●

Speed limiter length

*****************************************************

Speed limiter length adjustment steps:

●

Loosen the locknut

●

Turn the adjuster

in or out until the

specified speed limiter length is obtained.

●

Tighten the locknut.

WARNING

●

Particularly for a beginner rider, the
speed limiter should be screwed in
completely. Screw it out little by little as
their riding technique improves. Never
remove the speed limiter for a beginning
rider.

●

For proper throttle lever operation do not
turn out the adjuster more than 12 mm
(0.47 in). Also, always adjust the throttle
lever free play to 3 ~ 5 mm (0.12 ~ 0.20 in).

*****************************************************

Turning in

Speed limiter length is
decreased.

Turning out

Speed limiter length is
increased.

ADJUSTING THE STARTER CABLE

1.Remove:

●

Seat

●

Fuel tank side panel (left)
Refer to “SEAT, CARRIERS, FENDERS
AND FUEL TANK”.

3 - 18

CHK

ADJ

ADJUSTING THE STARTER CABLE

2.Adjust:

*****************************************************

Adjustment steps:

●

Disconnect the starter cable

from the

carburetor body.

NOTE:

Do not remove the starter plunger

from the

starter cable.

●

Measure the starter plunger stroke distance

of the starter lever

fully close to fully

open position. If the distance is out of
specification adjust it as described below.

Fully closed position

Fully open position

●

Pull back the boot

●

Loosen the locknut

●

Turn the adjuster

in or out until the correct

free play is obtained.

●

Tighten the locknut

●

Push in the boot

●

Connect the starter cable to the carburetor.

WARNING

After adjusting the cable, turn the
handlebar to right and left, and make sure
that the engine idling speed does not
increase.

*****************************************************

Starter plunger stroke distance:

15 mm (0.59 in)

Turning in

Free play increased.

Turning out Free play decreased.

3.Install:

●

Fuel tank side panel (left)

●

Seat
Refer to “SEAT, CARRIERS, FENDERS
AND FUEL TANK”.

3 - 19

CHK

ADJ

CHECKING THE SPARK PLUG

1.Remove:

●

Seat

●

Fuel tank side panel (right)
Refer to “SEAT, CARRIERS, FENDERS
AND FUEL TANK”.

2.Remove:

●

Spark plug

3.Check:

●

Spark plug type
Incorrect

→

Replace.

Standard spark plug:

DR8EA/NGK

4.Check:

●

Electrode

Wear/damage

→

Replace.

●

Insulator

Abnormal color

→

Replace.

Normal color is a medium-to-light tan color.

5.Clean the spark plug with a spark plug

cleaner or wire brush.

6.Measure:

●

Plug gap

Use a wire gauge or feeler gauge.
Out of specification

→

Regap.

7.Tighten:

●

Spark plug

NOTE:

Before installing a spark plug, clean the gasket
surface and plug surface.

8.Install:

●

Fuel tank side panel (right)

●

Seat
Refer to “SEAT, CARRIERS, FENDERS
AND FUEL TANK”.

Spark plug gap:

0.6 ~ 0.7 mm (0.024 ~ 0.028 in)

18 Nm (1.8 m • kg, 13 ft • lb)

3 - 20

CHK

ADJ

CHECKING THE IGNITION TIMING

NOTE:

Engine idling speed and throttle cable free play
should be adjusted properly before checking
the ignition timing.

1.Remove:

●

Seat

●

Fuel tank side panel (right)
Refer to “SEAT, CARRIERS, FENDERS
AND FUEL TANK”.

2.Attach:

●

Inductive tachometer or engine tachometer

●

Timing light
(to spark plug lead)

3.Check:

●

Ignition timing

*****************************************************

Checking steps:

●

Warm up the engine and keep it at the
specified speed.

●

Remove the recoil starter

●

Remove the timing plug

●

Visually check the stationary pointer

verify it is within the required firing range

indicated on the flywheel.
Incorrect firing range

→

Check the pulser coil

assembly.

●

Install the timing plug.

●

Install the recoil starter.

*****************************************************

Inductive tachometer:

P/N. YU-8036-A

Engine tachometer:

P/N. 90890-03113

Timing light:

P/N. YM-33277-A, 90890-03141

Engine speed:

1,450 ~ 1,550 r/min

Recoil starter bolt:

10 Nm (1.0 m • kg, 7.2 ft • Ib)
LOCTITE

3 - 21

CHK

ADJ

4.Detach:

●

Timing light

●

Inductive tachometer or engine tachometer

5.Install:

●

Seat

●

Fuel tank side panel (right)
Refer to “SEAT, CARRIERS, FENDERS
AND FUEL TANK”.

MEASURING THE COMPRESSION
PRESSURE

NOTE:

Insufficient compression pressure will result in
a loss of performance.

1.Check:

●

Valve clearance
Out of specification

→

Adjust.

Refer to “ADJUSTING THE VALVE
CLEARANCE”.

2.Start the engine and let it warm up for

several minutes.

3.Stop the engine.
4.Remove:

●

Seat

●

Fuel tank side panel (right)
Refer to “SEAT, CARRIERS, FENDERS
AND FUEL TANK”.

5.Remove:

●

Spark plug

6.Attach:

●

Adapter

●

Compression gauge

Compression gauge:

P/N. YU-33223, 90890-03081

Adapter:

P/N. YU-33223-3, 90890-04082

CHECKING THE IGNITION TIMING/

MEASURING THE COMPRESSION PRESSURE

3 - 22

CHK

ADJ

MEASURING THE COMPRESSION PRESSURE

7.Measure:

●

Compression pressure
Above the maximum pressure:
Check the cylinder head, valve surfaces, and
piston crown for carbon deposits.
Below the minimum pressure:
Squirt a few drops of oil into the affected
cylinder and measure again.

●

Refer to the table below.

*****************************************************

Measurement steps:

●

Crank over the engine with the electric
starter (be sure the battery is fully charged)
with the throttle wide-open until the
compression reading on the gauge
stabilizes.

WARNING

When cranking the engine, ground the
spark plug lead to prevent sparking.

*****************************************************

Compression pressure

(with oil introduced into cylinder)

Reading

Diagnosis

Higher than
without oil

Worn or damaged pistons

Same as
without oil

Defective ring(s), valves,
cylinder head gasket or
piston is possible.

Compression pressure
(at sea level):

Standard:

1,270 kPa (12.7 kg/cm

, 181 psi)

Minimum:

1,105 kPa (11.1 kg/cm

, 158 psi)

Maximum:

1,422 kPa (14.2 kg/cm

, 202 psi)

8.Install:

●

Spark plug

9.Remove:

●

Fuel tank side panel (right)

●

Seat
Refer to “SEAT, CARRIERS, FENDERS
AND FUEL TANK”.

18 Nm (1.8 m • kg, 13 ft • lb)

Yamaha YFM45FAR, YFM450FAR. Service Manual - part 5