check engine YAMAHA YFZ50 2018 Owners Manual

EBU17421
TABLE OF CONTENTS
LOCATION OF THE WARNING AND
SPECIFICATION LABELS .............................. 1-1
SAFETY INFORMATION ................................ 2-1
DESCRIPTION................................................ 3-1Left view ...................................................... 3-1
Right view.................................................... 3-1
Controls and instruments............................ 3-2
INSTRUMENT AND CONTROL
FUNCTIONS ................................................... 4-1 Main switch ................................................. 4-1
Handlebar switches .................................... 4-1
Engine stop switch with lanyard ................. 4-2
Throttle lever ............................................... 4-3
Speed limiter ............................................... 4-3
Front brake lever ......................................... 4-5
Rear brake lever .......................................... 4-6
Parking brake .............................................. 4-6
Kickstarter ................................................... 4-7
Fuel tank cap .............................................. 4-8
Fuel ............................................................. 4-8
Fuel cock................................................... 4-10 Starter (choke) ......................................... 4-11
Seat .......................................................... 4-12
Adjusting the rear shock absorber ........... 4-13
PRE-OPERATION CHECKS .......................... 5-1 Fuel ............................................................. 5-3
Engine oil .................................................... 5-3
Transmission oil .......................................... 5-3
Front and rear brakes ................................. 5-3
Throttle lever ............................................... 5-3
Drive chain .................................................. 5-3
Tires ............................................................ 5-3
Chassis fasteners ....................................... 5-6
Instruments and switches........................... 5-6
OPERATION .................................................. 6-1 Starting a cold engine................................. 6-1
Starting a warm engine............................... 6-3
Engine break-in........................................... 6-3
Parking........................................................ 6-3
Parking on a slope ...................................... 6-4
Accessories and loading ............................ 6-5UBW461E0.book Page 1 Tuesda y, January 31, 2017 5:13 PM

RIDING YOUR ATV ........................................ 7-1GETTING TO KNOW YOUR ATV ................ 7-2
RIDE WITH CARE AND GOOD JUDGMENT .............................................. 7-2
BE CAREFUL WHERE YOU RIDE ............... 7-9
TURNING YOUR ATV................................ 7-12
CLIMBING UPHILL ................................... 7-13
RIDING DOWNHILL .................................. 7-16
CROSSING A SLOPE................................ 7-17
CROSSING THROUGH SHALLOW WATER .................................................... 7-18
RIDING OVER ROUGH TERRAIN ............. 7-20
SLIDING AND SKIDDING .......................... 7-20
WHAT TO DO IF... ..................................... 7-21
WHAT TO DO... ......................................... 7-22
PERIODIC MAINTENANCE AND
ADJUSTMENT................................................ 8-1 Owner’s manual and tool kit ....................... 8-2
Periodic maintenance chart for the emission control system ........................... 8-3
General maintenance and lubrication chart .......................................................... 8-5
Removing and installing the panel .............. 8-9
Checking the spark plug ............................. 8-9
Engine oil................................................... 8-11
Transmission oil ........................................ 8-14 Cleaning the air filter element ................... 8-16
Cleaning the spark arrester ...................... 8-19
Adjusting the carburetor ........................... 8-20
Adjusting the engine idling speed ............ 8-20
Adjusting the throttle lever free play ......... 8-21
Valve clearance......................................... 8-22
Brakes....................................................... 8-22
Checking the front and rear brake
shoes ...................................................... 8-22
Adjusting the front brake lever free play... 8-23
Adjusting the rear brake lever free play .... 8-25
Drive chain slack....................................... 8-26
Cleaning and lubricating the drive chain ....................................................... 8-28
Checking and lubricating the cables ........ 8-29
Checking and lubricating the front and rear brake levers ..................................... 8-29
Checking the wheel hub bearings ............ 8-30
Lubricating the front arm pivots ............... 8-30
Lubricating the front knuckle pivots ......... 8-31
Lubricating the steering shaft ................... 8-31
Battery ...................................................... 8-32
Replacing the fuse .................................... 8-35
Removing a wheel .................................... 8-35
Installing a wheel ...................................... 8-36
Troubleshooting........................................ 8-37
Troubleshooting chart .............................. 8-38UBW461E0.book Page 2 Tuesda y, January 31, 2017 5:13 PM

2-4
2In the event of an accident
1. If serious injuries are incurred, you may be safer staying next to your vehicle; it may
shield you from oncoming riders. Depending
on your injuries and position in the trail; you
must make a judgment call as to whether you
should move to a position off the trail. If you
have sustained head, neck, or back injuries,
or cannot feel your limbs, you should not
move. Keep your helmet on and remain mo-
tionless. Lie down next to your vehicle and
wait for help.
2. If less serious injuries are incurred and you can walk, then move to a position off the trail.
Check yourself for injuries and apply first aid
as needed.
3. If your injuries are light, when safe to do so, move your vehicle off the trail to avoid colli-
sions with oncoming riders. Check for injuries
and apply first aid as necessary. If you can
physically operate your vehicle, inspect your
vehicle. If the vehicle is in safe operating con-
dition and you can safely operate it, restart it
and ride gently back to camp or other known
location where you can receive medical at- tention. If necessary, contact your riding party
or local authorities to let them know where
you are and what has happened.
In the event of a breakdown 1. If your vehicle will not restart or is not in safe operating condition, turn off the main switch
and engine stop switch. If the breakdown oc-
curs at twilight or night, leave the main switch
on so that your lights may warn other riders of
your stopped vehicle.
2. Get out of danger. Check for oncoming vehi- cles and when safe, push your vehicle to the
side of the trail or even off the main trail to
avoid any possible collisions with oncoming
riders. If you cannot move your vehicle by
yourself, when safe, walk to the nearest van-
tage point and signal an oncoming rider to
help you push your vehicle to a safe place off
the trail.
3. Inspect your vehicle for any immediate haz- ardous conditions. The most obvious hazard-
ous conditions are leaking fuel and
ungrounded or broken wiring. Visually check
for broken wiring and leaking fuel. Leaking
fuel can be confirmed by the odor of gasoline.
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2-5
2
4. Once immediate safety hazards are con-
firmed not to exist, you may remove your hel-
met to more closely inspect your vehicle.
Check for external signs of wear, broken
parts, fluid leaks, cracks in the frame, sus-
pension damage, wheel damage, and so on.
Fuel, oil, and coolant usually give off a notice-
able odor.
5. If your vehicle will not restart or if it is unsafe to ride, then turn off all vehicle systems (en-
gine stop switch, main switch, and fuel cock),
and then signal or go for help.
Aftermarket Parts, Accessories, and Modifica-
tions
While you may find aftermarket products similar in
design and quality to genuine Yamaha accesso-
ries, recognize that some aftermarket accessories
or modifications are not suitable because of po-
tential safety hazards to you or others. Installing
aftermarket products or having other modifica-
tions performed to your vehicle that change any of
the vehicle’s design or operation characteristics
can put you and others at greater risk of serious
injury or death. You are responsible for injuries re-
lated to changes in the vehicle. Keep the following
guidelines in mind, as well as those found in the Loading section (page 6-6) when mounting acces-
sories.

Never install accessories that would impair the
performance of your ATV. Carefully inspect the
accessory before using it to make sure that it
does not in any way reduce ground clearance,
limit suspension travel, steering travel or control
operation.
 Accessories fitted to the ATV can create insta-
bility due to improper weight distribution.
 Bulky or large accessories may seriously affect
the stability of the ATV.
 Certain accessories can displace the operator
from his or her normal riding position. This im-
proper position limits the freedom of movement
of the operator and may limit control ability,
therefore, such accessories are not recom-
mended.
 Use caution when adding electrical accesso-
ries. If electrical accessories exceed the capac-
ity of the ATV’s electrical system, an electric
failure could result, which could cause a dan-
gerous loss of lights or engine power. Also, the
battery tends to discharge more quickly if elec-
trical accessories are added.
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4-3
4

When your child has developed sufficient skill to
no longer need you to follow with the lanyard,
securely tie up the lanyard. However, you must
still closely supervise your child at all times dur-
ing ATV operation.
EBU18283Throttle leverOnce the engine is running, pushing the throttle le-
ver will increase the engine speed.
Regulate the speed of the ATV by varying the
throttle position. Because the throttle is spring-
loaded, the ATV will decelerate, and the engine
will return to an idle any time the throttle lever is re-
leased. Before starting the engine, check the throttle to be
sure it is operating smoothly. Make sure it returns
to the idle position as soon as the lever is released.
EBU36330Speed limiterYour ATV was delivered with two speed limiter de-
vices. A vehicle speed limiter adjusting screw and
a removable engine speed limiter plate. Yamaha
recommends that all beginning riders start off with
the vehicle speed limiter adjusting screw fully
turned in and the engine speed limiter plate in-
stalled to limit the amount of speed available while
they learn.1. Throttle lever
1
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4-9
4
of sparks, open flames, or other sources of
ignition such as the pilot lights of water heat-
ers and clothes dryers.
2. Do not overfill the fuel tank. When refueling, be sure to insert the pump nozzle into the fuel
tank filler hole. Stop filling when the fuel
reaches the bottom of the filler tube. Because
fuel expands when it heats up, heat from the
engine or the sun can cause fuel to spill out of
the fuel tank. For Europe
TIPWhen refueling, check that the gasoline pump
nozzle has same fuel identification mark.
1. Maximum fuel level
2. Fuel tank filler tube
2
1
Recommended fuel:
Regular unleaded gasoline only
Fuel tank capacity: 5.6 L (1.48 US gal, 1.23 Imp.gal)
Fuel reserve amount: 0.7 L (0.18 US gal, 0.15 Imp.gal)1. EN228 fuel identification mark
E10
1
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5-1
5
EBU19203
PRE-OPERATION CHECKS
EBU19226Inspect your vehicle each time you use it to make sure the vehicle is in safe operating condition. Always
follow the inspection and maintenance procedures and schedules described in the Owner’s Manual.
WARNING
EWB00482Failure to inspect or maintain the vehicle properly increases the possibility of an accident or equip-
ment damage. Do not operate the vehicle if you find any problem. If a problem cannot be corrected
by the procedures provided in this manual, have the vehicle inspected by a Yamaha dealer. Before using this vehicle, check the following points:
ITEMROUTINE PAGE
Fuel • Check fuel level in fuel tank,
and add recommended fuel if neces-
sary.
• Check fuel line for leakage. Correct if necessary. 4-8, 5-3
Engine oil • Check oil level in engine, and add recommended oil to specified
level if necessary.
• Check ATV for oil leakage. Correct if necessary. 5-3, 8-11
Transmission oil • Check ATV for oil leakage. Correct if necessary. 5-3, 8-14
Front brake • Check operation, and correct if necessary.
• Lubricate cable if necessary.
• Check lever free play, and adjust if necessary. 5-3, 8-22, 8-23
Rear brake • Check operation, and correct if necessary.
• Lubricate cable if necessary.
• Check lever free play, and adjust if necessary. 5-3, 8-22, 8-25
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5-3
5
EBU19542FuelMake sure that there is sufficient fuel in the tank.
(See page 4-8.)EBU19561Engine oilMake sure that the engine oil is at the specified
level. Add oil as necessary. (See page 8-11.)EBU34490Transmission oilMake sure that the transmission oil is at the spec-
ified level. Add oil as necessary. (See page 8-14.)EBU19653Front and rear brakesBrake levers
Check for correct free play in the brake levers. If
the free play is incorrect, adjust it. (See pages
8-23 and 8-25.)
 Check operation of the levers. They should
move smoothly and there should be a firm feel-
ing when the brake is applied. If not, have the
ATV checked by a Yamaha dealer. Brake operation
Test the brakes at slow speed after starting out to
make sure they are working properly. If the brakes
do not provide proper braking performance,
check the brake shoes for wear. (See page 8-22.)
EBU19762Throttle leverCheck the operation of the throttle lever. It must
open smoothly and spring back to the idle position
when released. Have a Yamaha dealer correct if
necessary.EBU19771Drive chainCheck the condition of the drive chain and check
the drive chain slack. Lubricate and adjust the
drive chain as necessary. (See page 8-26.)EBU19797TiresCheck tire pressure regularly to make sure it is at
the recommended specifications. Also check for
wear and damage.
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6-3
6
EBU20292Starting a warm engineFollow the same procedure as for starting a cold
engine, with the exception that the starter (choke)
is not required when the engine is warm. Instead,
start the engine with the throttle slightly open.EBU36860Engine break-inTIPFor ATVs equipped with an odometer or an hour
meter, follow the figures given in km (mi) or the
figures given in hours.
 For ATVs not equipped with an odometer or
hour meter, follow the figures given in hours. There is never a more important period in the life
of your engine than the first 240 km (150 mi) or 20
hours of riding. For this reason, you should read
the following material carefully.
Since the engine is brand new, do not put an ex-
cessive load on it for the first 240 km (150 mi) or
20 hours. The various parts in the engine wear and
polish themselves to the correct operating clear-
ances. During this period, prolonged full-throttle
operation or any condition that might result in en-
gine overheating must be avoided. 0–120 km (0–75 mi) or 0–10 hours
Avoid prolonged operation above 1/2 throttle.
Vary the speed of the ATV regularly. Do not oper-
ate it at one set throttle position.
120–240 km (75–150 mi) or 10–20 hours
Avoid prolonged operation above 3/4 throttle. Rev
the engine freely, but do not use full throttle at any
time.
240 km (150 mi) or 20 hours and beyond
The ATV can now be operated normally.
NOTICEECB00221If any engine trouble should occur during the
engine break-in period, immediately have a
Yamaha dealer check the ATV. EBU36370ParkingWhen parking the ATV, apply the rear brake lever,
stop the engine, apply the parking brake, and then
turn the fuel cock to “OFF”.
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7-5
7
Pre-operation checks
Always inspect your ATV each time you use it to
make sure the ATV is in safe operating condition.
Perform the pre-operation checks listed on page
5-1. Always follow the inspection and mainte-
nance procedures and schedules described in the
Owner’s Manual.
WARNING! Failure to inspect
the ATV before riding it or failure to maintain it
properly increases the possibility of an acci-
dent and equipment damage.
[EWB01433]
Speed limiter
For beginning riders, riders less experienced with
this model, or whenever limited speed is desir-
able, the throttle lever housing is equipped with a vehicle speed limiter. The speed limiter keeps the
throttle from fully opening, even when the throttle
lever is pushed to the maximum. Turning in the
adjusting screw limits th
e maximum engine power
available and decreases the maximum speed of
the ATV. Turning in the adjusting screw decreases
top speed, and turning it out increases top speed.
(See page 4-3.)
This model also has an engine speed limiter plate
to limit the amount of engine power available.
Yamaha recommends that all beginning riders start off with the engine speed limiter plate in-
stalled and the vehicle speed limiter adjusting
screw turned in to limit the amount of speed avail-
able while they learn. The vehicle speed limiter
may be gradually adjusted to increase maximum
speed as the beginner becomes more familiar with
operating the ATV. Parents should decide when to
adjust the ATV for more power as their young-
ster’s riding skills improve. Once the ATV rider can
operate with skill at the top speed permitted by
adjusting the vehicle speed limiter alone, the en-
gine speed limiter plate can be removed. Since re-
moval of this plate will result in a significant
increase in power, turn the vehicle speed limiter
adjusting screw back in again and adjust it out inUBW461E0.book Page 5 Tuesda y, January 31, 2017 5:13 PM