engine YAMAHA NMAX 155 2021 Owners Manual

Table of contentsSafety information ............................ 1-1
Further safe-riding points ............... 1-5
Description ....................................... 2-1
Left view ......................................... 2-1
Right view ....................................... 2-2
Controls and instruments ............... 2-3
Smart key system ........................... 3-1
Smart key system ........................... 3-1
Operating range of the smart key system .................................. 3-2
Handling of the smart key and mechanical keys ......................... 3-3
Smart key ....................................... 3-4
Replacing the smart key battery..... 3-6
Main switch .................................... 3-7
Stop an d Start System ..................... 4-1
Stop and Start System ................... 4-1
Stop and Start System operation ... 4-1
Special features .............................. 5-1
CCU (Communication Control Unit) ................................ 5-1
Instrument an d control functions ... 6-1
Indicator lights and warning lights............................................ 6-1
Multi-function meter unit ................ 6-3
Handlebar switches ...................... 6-10 Front brake lever ........................... 6-11
Rear brake lever ............................ 6-11
ABS ............................................... 6-12
Traction control system ................ 6-13
Fuel tank cap ................................ 6-14
Fuel ............................................... 6-15
Fuel tank overflow hose ................ 6-17
Catalytic converter ........................ 6-17
Seat ............................................... 6-17
Helmet holders .............................. 6-18
Storage compartments ................. 6-19
Adjusting the shock absorber
assemblies ................................. 6-20
Power outlet ................................. 6-21
Sidestand ...................................... 6-22
Ignition circuit cut-off system ....... 6-22
For your safety – pre-operation
checks ............................................... 7-1
Operation an d important ri din g
points ................................................. 8-1
Engine break-in ............................... 8-1
Starting the engine .......................... 8-2
Starting off ...................................... 8-2
Acceleration and deceleration ........ 8-3
Braking ............................................ 8-3
Tips for reducing fuel consumption ................................ 8-3
Parking ........................................... 8-4 Perio
dic maintenance an d
a d justment ........................................ 9-1
Tool kit ............................................ 9-1
Periodic maintenance chart for the emission control system ....... 9-2
General maintenance and lubrication chart .......................... 9-3
Removing and installing panels ...... 9-7
Checking the spark plug................. 9-9
Canister ........................................ 9-11
Engine oil and oil strainer ............. 9-11
Why Yamalube.............................. 9-13
Final transmission oil .................... 9-13
Coolant ......................................... 9-15
Air filter and V-belt case
air filter elements ....................... 9-16
Checking the throttle grip
free play..................................... 9-19
Valve clearance............................. 9-19
Tires .............................................. 9-19
Cast wheels .................................. 9-21
Checking the front and rear brake lever free play .................. 9-21
Checking the front and rear brake pads ................................ 9-22
Checking the brake fluid level ...... 9-23
Changing the brake fluid .............. 9-24
Checking the V-belt ...................... 9-24
Checking and lubricating the
cables ........................................ 9-25UBBDE0E0.book Page 1 Wednesday, June 2, 2021 2:57 PM

Safety information
1-2
1

Many accidents involve inexperi-
enced operators. In fact, many op-
erators who have been involved in
accidents do not even have a cur-
rent driver’s license.
• Make sure that you are qualified and that you only lend your
scooter to other qualified opera-
tors.
• Know your skills and limits. Staying within your limits may
help you to avoid an accident.
• We recommend that you prac- tice riding your scooter where
there is no traffic until you have
become thoroughly familiar with
the scooter and all of its con-
trols.
 Many accidents have been
caused by error of the scooter op-
erator. A typical error made by the
operator is veering wide on a turn
due to excessive speed or under-
cornering (insufficient lean angle
for the speed).
• Always obey the speed limit and never travel faster than warrant-
ed by road and traffic condi-
tions. • Always signal before turning or
changing lanes. Make sure that
other motorists can see you.
 The posture of the operator and
passenger is important for proper
control.
• The operator should keep both hands on the handlebar and
both feet on the operator foot-
rests during operation to main-
tain control of the scooter.
• The passenger should always hold onto the operator, the seat
strap or grab bar, if equipped,
with both hands and keep both
feet on the passenger footrests.
Never carry a passenger unless
he or she can firmly place both
feet on the passenger footrests.
 Never ride under the influence of
alcohol or other drugs.
 This scooter is designed for on-
road use only. It is not suitable for
off-road use. Protective Apparel
The majority of fatalities from scooter
accidents are the result of head inju-
ries. The use of a safety helmet is the
single most critical factor in the pre-
vention or reduction of head injuries.
 Always wear an approved helmet.
 Wear a face shield or goggles.
Wind in your unprotected eyes
could contribute to an impairment
of vision that could delay seeing a
hazard.
 The use of a jacket, substantial
shoes, trousers, gloves, etc., is ef-
fective in preventing or reducing
abrasions or lacerations.
 Never wear loose-fitting clothes,
otherwise they could catch on the
control levers or wheels and cause
injury or an accident.
 Always wear protective clothing
that covers your legs, ankles, and
feet. The engine or exhaust sys-
tem become very hot during or af-
ter operation and can cause
burns.
 A passenger should also observe
the above precautions.
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Safety information
1-3
1Avoi
d Car bon Monoxi de Poisonin g
All engine exhaust contains carbon
monoxide, a deadly gas. Breathing
carbon monoxide can cause head-
aches, dizziness, drowsiness, nausea,
confusion, and eventually death.
Carbon Monoxide is a colorless, odor-
less, tasteless gas which may be
present even if you do not see or smell
any engine exhaust. Deadly levels of
carbon monoxide can collect rapidly
and you can quickly be overcome and
unable to save yourself. Also, deadly
levels of carbon monoxide can linger
for hours or days in enclosed or poorly
ventilated areas. If you experience any
symptoms of carbon monoxide poi-
soning, leave the area immediately, get
fresh air, and SEEK MEDICAL TREAT-
MENT.  Do not run engine indoors. Even if
you try to ventilate engine exhaust
with fans or open windows and
doors, carbon monoxide can rap-
idly reach dangerous levels.
 Do not run engine in poorly venti-
lated or partially enclosed areas
such as barns, garages, or car-
ports. 
Do not run engine outdoors where
engine exhaust can be drawn into
a building through openings such
as windows and doors.
Loa din g
Adding accessories or cargo to your
scooter can adversely affect stability
and handling if the weight distribution
of the scooter is changed. To avoid the
possibility of an accident, use extreme
caution when adding cargo or acces-
sories to your scooter. Use extra care
when riding a scooter that has added
cargo or accessories. Here, along with
the information about accessories be-
low, are some general guidelines to fol-
low if loading cargo to your scooter:
The total weight of the operator, pas-
senger, accessories and cargo must
not exceed the maximum load limit.
Operation of an overloa ded vehicle
coul d cause an acci dent.
When loading within this weight limit,
keep the following in mind: 
Cargo and accessory weight
should be kept as low and close to
the scooter as possible. Securely
pack your heaviest items as close
to the center of the vehicle as pos-
sible and make sure to distribute
the weight as evenly as possible
on both sides of the scooter to
minimize imbalance or instability.
 Shifting weights can create a sud-
den imbalance. Make sure that
accessories and cargo are se-
curely attached to the scooter be-
fore riding. Check accessory
mounts and cargo restraints fre-
quently.
• Properly adjust the suspension for your load (suspension-ad-
justable models only), and
check the condition and pres-
sure of your tires.
• Never attach any large or heavy items to the handlebar, front
fork, or front fender. Such items
can create unstable handling or
a slow steering response.
 This vehicle is not desi gne d to
pull a trailer or to be attached to
a si decar.
Maximum loa d:
167 kg (368 lb)
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Safety information
1-4
1
Genuine Yamaha Accessories
Choosing accessories for your vehicle
is an important decision. Genuine
Yamaha accessories, which are avail- able only from a Yamaha dealer, have
been designed, tested, and approved
by Yamaha for use on your vehicle.
Many companies with no connection
to Yamaha manufacture parts and ac-
cessories or offer other modifications
for Yamaha vehicles. Yamaha is not in
a position to test the products that
these aftermarket companies produce.
Therefore, Yamaha can neither en-
dorse nor recommend the use of ac-
cessories not sold by Yamaha or
modifications not specifically recom-
mended by Yamaha, even if sold and
installed by a Yamaha dealer.
Aftermarket Parts, Accessories, an d
Mo difications
While you may find aftermarket prod-
ucts similar in design and quality to
genuine Yamaha accessories, recog-
nize that some aftermarket accesso-
ries or modifications are not suitable
because of potential safety hazards to
you or others. Installing aftermarket products or having other modifications
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
related to changes in the vehicle.
Keep the following guidelines in mind,
as well as those provided under “Load-
ing” when mounting accessories.
 Never install accessories or carry
cargo that would impair the per-
formance of your scooter. Careful-
ly inspect the accessory before
using it to make sure that it does
not in any way reduce ground
clearance or cornering clearance,
limit suspension travel, steering
travel or control operation, or ob-
scure lights or reflectors.
• Accessories fitted to the han- dlebar or the front fork area can
create instability due to improp-
er weight distribution or aerody-
namic changes. If accessories
are added to the handlebar or
front fork area, they must be as
lightweight as possible and
should be kept to a minimum. • Bulky or large accessories may
seriously affect the stability of
the scooter due to aerodynamic
effects. Wind may attempt to lift
the scooter, or the scooter may
become unstable in cross
winds. These accessories may
also cause instability when
passing or being passed by
large vehicles.
• Certain accessories can dis- place the operator from his or
her normal riding position. This
improper position limits the
freedom of movement of the
operator and may limit control
ability, therefore, such accesso-
ries are not recommended.
 Use caution when adding electri-
cal accessories. If electrical ac-
cessories exceed the capacity of
the scooter’s electrical system, an
electric failure could result, which
could cause a dangerous loss of
lights or engine power.
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Description
2-2
2
EAU10421
Right view
1
10 9 8 7 623 4 5
1. Tail/brake light
2. Battery (page 9-28)
3. Storage compartment B (page 6-19)
4. Fuse box (page 9-29)
5. Headlight (page 9-31)
6. Coolant reservoir (page 9-15)
7. Spark plug (page 9-9)
8. Engine oil drain bolt A (page 9-11)
9. Engine oil drain bolt B (page 9-11)
10.Engine oil filler cap (page 9-11)
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Smart key system
3-8
3taken place), the main switch can be
turned while the smart key system indi-
cator light is on (approximately 4 sec-
onds).
WARNING
EWA18720
Never turn the main switch to
“OFF”, “ ”, or “OPEN” while the ve-
hicle is movin
g. Otherwise the elec-
trical systems will b e switched off,
which may result in loss of control or
an acci dent.TIPDo not push the main switch knob re-
peatedly or turn the main switch back
and forth excessively (beyond normal
use). To protect the main switch from
damage, the smart key system will
temporarily disable, and the smart key
system indicator light will flash. If this
occurs, wait until the indicator light
stops flashing, and then operate the
main switch.The main switch positions are de-
scribed below.
EAU76502
ON
All electrical circuits are supplied with
power, and the engine can be started.
To turn the vehicle power on1. Turn the smart key on and bring it
within operating range.
2. Push the main switch knob and the smart key indicator light will
come on for approximately 4 sec-
onds.
3. While the smart key system indi- cator light is on, turn the main
switch to “ON”. All of the turn sig-
nal lights will flash twice and the
vehicle power will turn on.
TIPIf the vehicle battery voltage is
low, the turn signal lights will not
flash.
 See “Emergency mode” on page
9-38 for information on turning the
vehicle power on without the
smart key.
EAU76511
OFF
All electrical systems are off.
To turn the vehicle power off1. With the smart key turned on and
within operating range, turn the
main switch to “OFF”.
1. Push.
2. Turn.1 2
1. Turn.
1
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Stop and Start System
4-1
4
EAU76825
Stop an d Start SystemThe Stop and Start System stops the
engine automatically when the vehicle
is stopped in order to prevent noise,
control exhaust emissions, and reduce
fuel consumption.
When the rider turns the throttle grip
slightly, the engine restarts automati-
cally and the vehicle starts off.NOTICE
ECA23961
When parkin g the vehicle or leavin g
the vehicle unatten ded , be sure to
turn the main switch off. If the Stop
an d Start System is left turne d on,
the battery could become dis- char
ged an d it may not be possi ble
to restart the en gine due to insuffi-
cient battery volta ge.
TIP Although the engine normally
stops at the same time as the ve-
hicle, there may be a delay when
operating the vehicle under 10
km/h, such as in heavy traffic.
 If you think the battery voltage is
low because the engine cannot be
started using the starter switch or
for some other reason, do not turn
on the Stop and Start System.
 Have a Yamaha dealer check the
battery at the intervals specified in
the periodic maintenance chart.
EAU76671
Stop an d Start System opera-
tion
EAU76687
Activatin g the Stop an d Start Sys-
tem 1. Turn the main switch on.
2. Set the Stop and Start System switch to “ ”.
1. Stop and Start System indicator light “ ”
1
ON
A
AAA
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Stop and Start System
4-2
4 3. The Stop and Start System acti-
vates and the indicator light
comes on when the following con-
ditions are met: The Stop and Start System
switch is set to “ ”.
 After the engine was warmed
up, the engine was left idling
for a certain period.
 The vehicle has traveled at a
speed of 10 km/h or higher.
4. To turn off the Stop and Start Sys- tem, set the Stop and Start Sys-
tem switch to “ ”.
TIPTo preserve battery power, the
Stop and Start System may not
activate.
 If the Stop and Start System does
not activate, have a Yamaha deal-
er check the battery.
EAU76832
Stop the en gine
The engine will stop automatically
when the following conditions are met:  The Stop and Start System switch
is set to “ ”.
 The “ ” indicator light on the
multi-function meter is on.
 The vehicle is stopped with the
throttle grip fully returned. At this time, the “ ” indicator light
starts flashing to indicate that the en-
gine is currently stopped by the Stop
and Start System.
EAU76704
Restart the en
gine
If the throttle grip is turned while the
Stop and Start System indicator light is
flashing, the engine will automatically
restart and the “ ” indicator light will
stop flashing.
1. On
A1
A
AAA
A
A
1. On
2. Flashing
A
1
2
A
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Instrument and control functions
6-1
6
EAU77123
In dicator lig hts and warning
lig hts
EAU88900
Turn si gnal in dicator li ghts “ ”
an d“”
Each indicator light will flash when its
corresponding turn signal lights are
flashing.
EAU88910
Hi gh beam in dicator li ght “ ”
This indicator light comes on when the
high beam of the headlight is switched
on.
EAU88712
Malfunction in dicator li ght
(MIL) “ ”
This light comes on or flashes if a prob-
lem is detected in the engine or other
vehicle control system. If this occurs,
have a Yamaha dealer check the on-
board diagnostic system. The electri-
cal circuit of the warning light can be
checked by turning the vehicle power
on. The light should come on for a few
seconds, and then go off. If the light
does not come on initially when the ve-
hicle power is turned on, or if the light
remains on, have a Yamaha dealer
check the vehicle.
NOTICE
ECA26820
If the MIL starts flashin g, re duce en-
g ine spee d to prevent exhaust sys-
tem damag e.TIPThe engine is sensitively monitored by
the on-board diagnostic system to de-
tect deterioration and malfunction of
the emission control system. Therefore
the MIL may come on or flash due to
vehicle modifications, lack of mainte-
nance, or excessive/improper use of
the vehicle. To prevent this, observe
these precautions.
 Do not attempt to modify the soft-
ware of the engine control unit.
 Do not add any electrical acces-
sories that interfere with engine
control.
 Do not use aftermarket accesso-
ries or parts such as suspension,
spark plugs, injectors, exhaust
system, etc.
 Do not change the drivetrain
specifications (chain, sprockets,
wheels, tires, etc.).
1. Left turn signal indicator light “ ”
2. Incoming notification indicator light “ ”
3. Traction control system indicator
light “ ”
4. ABS warning light “ ”
5. High beam indicator light “ ”
6. Malfunction indicator light “ ”
7. Stop and Start System indicator light “ ”
8. Smart key system indicator light “ ”
9. Incoming call indicator light “ ”
10.Right turn signal indicator light “ ”
4
110
5
6
7
8
23 9
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Instrument and control functions
6-2
6 
Do not remove or alter the O2 sen-
sor, air induction system, or ex-
haust parts (catalysts or EXUP,
etc.).
 Maintain V-belt and drive belt (if
equipped) properly.
 Maintain correct tire pressure.
 Do not operate the vehicle in an
extreme manner. For example, re-
peated or excessive opening and
closing of the throttle, racing,
burnouts, wheelies, etc.
EAU88890
ABS warnin g li ght “ ”
This warning light comes on when the
vehicle is first turned on, and goes off
after starting riding. If the warning light
comes on while riding, the anti-lock
brake system may not work correctly.
WARNING
EWA16043
If the ABS warnin g lig ht does not
turn off after reachin g 10 km/h (6
mi/h), or if the warnin g li ght comes
on while ri din g:
 Use extra caution to avoi d pos-
si ble wheel lock d uring emer-
g ency brakin g. 
Have a Yamaha dealer check
the vehicle as soon as possib le.
TIPThe ABS warning light may come on
while revving the engine with the vehi-
cle on its centerstand, but this does
not indicate a malfunction.
EAU88930
Traction control system indicator
li g ht “ ”
This indicator light will flash when trac-
tion control has engaged.
If the traction control system is turned
off, this indicator light will come on.
(See page 6-13.)TIPWhen the vehicle is turned on, the light
should come on for a few seconds and
then go off. If the light does not come
on, or if the light remains on, have a
Yamaha dealer check vehicle.
EAUN2770
Smart key system in dicator
li g ht “ ”
This indicator light communicates the
status of the smart key system. When
the smart key system is operating nor-
mally, this indicator light will be off. If
there is an error in the smart key sys-
tem, the indicator light will flash. The
indicator light will also flash when com-
munication between the vehicle and
smart key takes place and when cer-
tain smart key system operations are
carried out.
EAUN2830
Stop an d Start System in dicator
li g ht “ ”
This indicator light comes on when the
Stop and Start System activates. The
indicator light will flash when the en-
gine is automatically stopped by the
Stop and Start System.TIPEven if the Stop and Start Switch is set
to Ž, this indicator light may not
come on. (See page 4-1.)
A
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