check engine YAMAHA YFZ50 2018 Owner's Manual

8-20
8
WARNING
EWB02341Do not start the engine when cleaning the
spark arrester, otherwise it could cause injury
to the eyes, burns, carbon monoxide poison-
ing, possibly leading to death, and start a fire.
Always let the exhaust system cool prior to
touching exhaust components. EBU23941Adjusting the carburetorThe carburetor should be checked and, if neces-
sary, adjusted at the intervals specified in the pe-
riodic maintenance and lubrication chart. The
carburetor is an important part of the engine and
requires very sophisticated adjustment. There-
fore, most carburetor adjustments should be left
to a Yamaha dealer, who has the necessary pro-
fessional knowledge and experience. The adjust-
ment described in the following section, however,
may be performed by the owner as part of routine
maintenance.
NOTICEECB00481The carburetor has been set and extensively
tested at the Yamaha factory. Changing these
settings without sufficient technical knowl-
edge may result in poor performance of or
damage to the engine. EBU24001Adjusting the engine idling speedThe engine idling speed must be checked and, if
necessary, adjusted as follows at the intervals
specified in the periodic maintenance and lubrica-
tion chart.TIPA diagnostic tachometer is needed to make this
adjustment. 1. Start the engine and warm it up.TIPThe engine is warm when it quickly responds to
the throttle. 2. Attach the tachometer to the spark plug lead.
Tightening torque:
Tailpipe bolt:10 N·m (1.0 kgf·m, 7.4 lb·ft)
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3. Check the engine idling speed and, if neces-
sary, adjust it to specification by turning the
throttle stop screw at the carburetor. To in-
crease the engine idling speed, turn the throt-
tle stop screw in direction (a), and to decrease
it, turn the screw in direction (b).
TIPIf the specified idling speed cannot be obtained as
described above, have a Yamaha dealer make the
adjustment. EBU33950Adjusting the throttle lever free playThe throttle lever free play should be checked and,
if necessary, adjusted at the intervals specified in
the periodic maintenance and lubrication chart.
The throttle lever free play should measure 2.0–3.2
mm (0.08–0.13 in) as shown. Periodically check
the throttle lever free play and, if necessary, adjust
it as follows.TIPThe engine idling speed must be checked, and
adjusted if necessary, before adjusting the throttle
lever free play. 1. Slide the rubber covers apart.
2. Loosen the locknut.
3. To increase the throttle lever free play, turnthe throttle lever free play adjusting nut in di-
rection (a). To decrease the throttle lever free
play, turn the adjusting nut in direction (b).
1. Throttle stop screwEngine idling speed:1600–1800 r/min
(a)
(b)
1
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84. Tighten the locknut.
5. Slide the rubber covers to their original posi-
tions.
EBU24061Valve clearanceThe valve clearance changes with use, resulting in
improper air-fuel mixture and/or engine noise. To
prevent this from occurring, the valve clearance
must be adjusted by a Yamaha dealer at the inter-
vals specified in the periodic maintenance and lu-
brication chart.
EBU29602BrakesReplacement of brake components requires pro-
fessional knowledge. Brake service should be
performed by a Yamaha dealer.
WARNING
EWB02572Operating with improperly serviced or adjust-
ed brakes could lead to a loss in braking ability
and an accident. EBU34511Checking the front and rear brake
shoesThe front and rear brake shoes must be checked
for wear at the intervals specified in the periodic
maintenance and lubrication chart. Without disas-
sembling the brake, this can be performed by
checking the position of the brake lever free play
adjusting bolts or nut.
Front brakes
To check front brake shoe wear, check the posi-
tion of the adjusting bolts. If a bolt extends more
than 12 mm (0.47 in) from its locknut, the brake
shoes need to be replaced.
1. Rubber cover
2. Throttle lever free play adjusting nut
3. Locknut
4. Throttle lever free play
1
2
3
1
4
(a)(b)
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EBU36413Replacing the fuseIf an electrical problem is suspected, check the
fuse and replace it if necessary as follows.NOTICEECB00641To prevent accidental short-circuiting, turn off
the main switch when checking or replacing a
fuse. 1. Turn off all electrical systems. (See page 4-1.)
2. Remove panel A. (See page 8-9.)3. Remove the blown fuse, and then install a
new fuse of the specified amperage.
WARNING! Always use a fuse of the spec- ified rating, and never use a substitute ob-
ject in place of the proper fuse. An
improper fuse or a substitute object can
cause damage to the electrical system,
which could lead to a fire.
[EWB02173]
4. Turn on the main switch and start the engine.
5. If the fuse immediately blows again, have a Yamaha dealer check the vehicle.EBU34030Removing a wheel1. Place the ATV on a level surface.
2. Loosen the wheel bolts.
1. Fuse
2. Spare fuse21
Specified fuse:7.5 A
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EBU25754Troubleshooting chart
Check the fuel level in
the fuel tank.1. Fuel
There is enough fuel.There is no fuel.
Check the battery.
Supply fuel.
The engine does not start.
Check the battery.
The engine does not start.
Check the ignition.
Operate the electric starter.4. Compression
There is compression.
There is no compression.
The engine does not start. Have a Yamaha dealer check the ATV.Have a Yamaha dealer check the ATV.
Remove the spark plug
and check the electrodes.3. Ignition
Wipe off with a dry cloth and correct the
spark plug gap, or replace the spark plug. Have a Yamaha dealer check the ATV.
The engine does not start.
Check the compression.
Operate the electric starter.2. Battery
The engine turns over
quickly.
The engine turns over
slowly.
The battery is good.Check the battery lead connections,
and have a Yamaha dealer charge
the battery if necessary.
DryWet
Open the throttle halfway and operate
the electric starter.
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INDEX
AAccessories and loading ................................................ 6-5
Air filter element, cleaning ............................................ 8-16BBattery .......................................................................... 8-32
Brake lever free play, adjusting the front ..................... 8-23
Brake lever free play (rear), adjusting ........................... 8-25
Brake lever, front ............................................................ 4-5
Brake lever, rear ............................................................. 4-6
Brake levers, checking and lubricating ........................ 8-29
Brakes .......................................................................... 8-22
Brakes, front and rear .................................................... 5-3CCables, checking and lubricating ................................. 8-29
Carburetor, adjusting ...................................................8-20
Chassis fasteners ........................................................... 5-6
Cleaning ......................................................................... 9-1DDrive chain ..................................................................... 5-3
Drive chain, cleaning and lubricating ........................... 8-28
Drive chain slack .......................................................... 8-26EEngine break-in .............................................................. 6-3
Engine, cold start ........................................................... 6-1
Engine idling speed ...................................................... 8-20
Engine oil .............................................................. 5-3, 8-11
Engine, starting a warm ................................................. 6-3
Engine stop switch ......................................................... 4-1
Engine stop switch with lanyard .................................... 4-2
FFront and rear brake shoes, checking ......................... 8-22
Front arm pivots, lubricating ........................................ 8-30
Front knuckle pivots, lubricating .................................. 8-31
Fuel ........................................................................ 4-8, 5-3
Fuel cock ...................................................................... 4-10
Fuel tank cap ................................................................. 4-8
Fuse, replacing ............................................................. 8-35HHandlebar switches ....................................................... 4-1IIdentification numbers ................................................. 11-1
Instruments and switches .............................................. 5-6KKickstarter ...................................................................... 4-7LLabel locations ............................................................... 1-1MMain switch .................................................................... 4-1
Maintenance and lubrication chart ................................ 8-5
Maintenance chart, emission control system ................ 8-3
Model label .................................................................. 11-1OOwner’s manual and tool kit .......................................... 8-2PPanel, removing and installing ....................................... 8-9
Parking ........................................................................... 6-3
Parking brake ................................................................. 4-6
Parking on a slope ......................................................... 6-4
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