check engine YAMAHA YFZ50 2021 Owner's Manual

9-19
9ment removed. This will allow unfiltered air
to enter the engine, causing rapid engine
wear and possible engine damage. Addi-
tionally, operation without the air filter ele-
ment will affect carburetor jetting with
subsequent poor performance and possi-
ble engine overheating.
[ECB00462]
10. Install the seat.TIPThe air filter element should be cleaned every 20–
40 hours. It should be cleaned and lubricated
more often if the ATV is operated in extremely dusty areas. When servicing the air filter element,
be sure to check the air inlet of the air filter case
for obstructions.
EBU28905Cleaning the spark arresterBe sure the exhaust pipe and muffler are cool be-
fore cleaning the spark arrester.1. Tailpipe bolt
2. Tailpipe
3. Spark arrester
4. Gasket
1
2
3
4
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9
WARNING
EWB02342Always let the exhaust system cool prior to
touching exhaust components.
Do not start the engine with the spark arrester
removed. Sparks or exhaust particulate can
cause eye injury, burns, or start a fire. 1. Remove the tailpipe bolts.
2. Remove the tailpipe by pulling it out of themuffler, and then remove the gasket.
3. Tap the tailpipe lightly, and then use a wire brush to remove any carbon deposits from
the spark arrester portion of the tailpipe and
inside of the tailpipe housing.
4. Check the gasket for damage. Replace if nec- essary.
5. Install the gasket onto the tailpipe, then insert the tailpipe into the muffler and align the bolt
holes.
6. Install the bolts and tighten to the specified torque.
EBU23942Adjusting the carburetorThe carburetor should be checked and, if neces-
sary, adjusted at the intervals specified in the pe-
riodic maintenance chart. The carburetor is an
important part of the engine and requires very so-
phisticated adjustment. Therefore, most carbure-
tor adjustments should be left to a Yamaha dealer,
who has the necessary professional knowledge
and experience. The adjustment 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. EBU24002Adjusting the engine idling speedThe engine idling speed must be checked and, if
necessary, adjusted as follows at the intervals
specified in the periodic maintenance chart.
Tightening torque:
Tailpipe bolt:10 N·m (1.0 kgf·m, 7.4 lb·ft)
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9
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.
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. 1. Throttle stop screwEngine idling speed:1600–1800 r/min
(a)
(b)
1
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9
EBU33951Adjusting the throttle lever free playPeriodically check the throttle lever free play and
adjust if necessary.TIPThe engine idling speed must be checked and ad-
justed 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).
4. Tighten the locknut.
5. Slide the rubber covers to their original posi- tions.EBU24062Valve 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 chart.EBU29602BrakesReplacement of brake components requires pro-
fessional knowledge. Brake service should be
performed by a Yamaha dealer.
1. Rubber cover
2. Throttle lever free play adjusting nut
3. Locknut
4. Throttle lever free playThrottle lever free play:2.0–3.2 mm (0.08–0.13 in)
1
2
3
1
4
(a)(b)
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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. Install the panel.
6. 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. 3. Elevate the ATV and place a suitable stand
under the frame.
4. Remove the bolts from the wheel.
5. Remove the wheel.
EBU34042Installing a wheel1. Install the wheel with the arrow mark pointing in the forward rotating direction of the wheel,
and then install the wheel bolts.
Specified fuse:
7.5 A1. Wheel bolt
1
1
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9
EBU25812Troubleshooting 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.
Recharge the battery or use the
kickstarter.
DryWet
Open the throttle halfway and try
starting the engine.
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12
INDEX
AAccessories and loading ................................................ 7-5
Air filter element, cleaning ........................................... 9-16BBattery ......................................................................... 9-32
Brake lever free play, adjusting the front ..................... 9-24
Brake lever free play (rear), adjusting .......................... 9-26
Brake lever, front ........................................................... 5-5
Brake lever, rear ............................................................. 5-6
Brake levers, checking and lubricating ........................ 9-30
Brakes .......................................................................... 9-22
Brakes, front and rear .................................................... 6-3CCables, checking and lubricating ................................ 9-29
Carburetor, adjusting ................................................... 9-20
Chassis fasteners .......................................................... 6-6
Cleaning ....................................................................... 10-1DDrive chain ..................................................................... 6-3
Drive chain, cleaning and lubricating ........................... 9-29
Drive chain slack .......................................................... 9-26EEngine break-in .............................................................. 7-3
Engine, cold start ........................................................... 7-1
Engine idling speed ..................................................... 9-20
Engine oil ..............................................................6-3, 9-11
Engine, starting a warm ................................................. 7-3
Engine stop switch ........................................................ 5-1
Engine stop switch with lanyard .................................... 5-2
FFront and rear brake shoes, checking ......................... 9-23
Front arm pivots, lubricating ........................................ 9-31
Front knuckle pivots, lubricating ................................. 9-31
Fuel ......................................................................... 5-9, 6-3
Fuel cock ..................................................................... 5-10
Fuel tank cap ................................................................. 5-8
Fuse, replacing ............................................................ 9-35HHandlebar switches ....................................................... 5-1IIdentification numbers ................................................... 1-1
Instruments and switches .............................................. 6-6KKickstarter ...................................................................... 5-7LLabel locations ............................................................... 2-1MMain switch .................................................................... 5-1
Maintenance and lubrication chart ................................ 9-5
Maintenance chart, emission control system ................ 9-3
Model label .................................................................... 1-1OOwner’s Manual and tool kit .......................................... 9-2PPanel, removing and installing ....................................... 9-9
Parking ........................................................................... 7-3
Parking brake ................................................................. 5-6
Parking on a slope ......................................................... 7-4
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