ECU YAMAHA NMAX 155 2021 Owners Manual

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
1-5
1Aftermarket Tires an
d Rims
The tires and rims that came with your
scooter were designed to match the
performance capabilities and to pro-
vide the best combination of handling,
braking, and comfort. Other tires, rims,
sizes, and combinations may not be
appropriate. Refer to page 9-19 for tire
specifications and more information on
replacing your tires.
Transportin g the Scooter
Be sure to observe following instruc-
tions before transporting the scooter in
another vehicle.  Remove all loose items from the
scooter.
 Point the front wheel straight
ahead on the trailer or in the truck
bed, and choke it in a rail to pre-
vent movement.
 Secure the scooter with tie-downs
or suitable straps that are at-
tached to solid parts of the scoot-
er, such as the frame or upper
front fork triple clamp (and not, for
example, to rubber-mounted han-
dlebars or turn signals, or parts
that could break). Choose the lo- cation for the straps carefully so
the straps will not rub against
painted surfaces during transport.
 The suspension should be com-
pressed somewhat by the tie-
downs, if possible, so that the
scooter will not bounce exces-
sively during transport.
EAU57600
Further safe-ri din g points Be sure to signal clearly when
making turns.
 Braking can be extremely difficult
on a wet road. Avoid hard braking,
because the scooter could slide.
Apply the brakes slowly when
stopping on a wet surface.
 Slow down as you approach a
corner or turn. Once you have
completed a turn, accelerate
slowly.
 Be careful when passing parked
cars. A driver might not see you
and open a door in your path.
 Railroad crossings, streetcar rails,
iron plates on road construction
sites, and manhole covers be-
come extremely slippery when
wet. Slow down and cross them
with caution. Keep the scooter up-
right, otherwise it could slide out
from under you.
 The brake pads or linings could
get wet when you wash the scoot-
er. After washing the scooter,
check the brakes before riding.
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Safety information
1-6
1

Always wear a helmet, gloves,
trousers (tapered around the cuff
and ankle so they do not flap), and
a brightly colored jacket.
 Do not carry too much luggage on
the scooter. An overloaded scoot-
er is unstable. Use a strong cord
to secure any luggage to the carri-
er (if equipped). A loose load will
affect the stability of the scooter
and could divert your attention
from the road. (See page 1-3.)
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Smart key system
3-6
3
EAUN2712
Replacing the smart key bat-
teryReplace the battery in the following sit-
uations.
 The smart key system indicator
light flashes for about 20 seconds
when the power of the vehicle is
turned on.
 The answer-back function does
not operate when the smart key
button is pushed.
WARNING
EWA20630
The smart key contains a button cell
b attery.
 Keep new an d use d b atteries
away from chil dren. 
If the b attery compartment d oes
not close securely, stop usin g
the smart key an d keep it away
from chil dren.
Explosion Hazar d - d o not mishan-
d le the battery.
 Dan ger of explosion if battery is
incorrectly replace d.
 Replace only with the same or
equivalent type.
 Do not expose smart key to ex-
cessive heat, such as sunshine
or fire.
Chemical Burn Hazar d - do not in-
g est the battery.
 If the battery is swallowed , it
can cause severe internal burns
in just 2 hours an d can lea d to
d eath.
 If you think batteries mi ght have
b een swallowed or placed in-
si de any part of the body, seek
imme diate me
dical attention.
NOTICE
ECA15785

Use a cloth when openin g the
smart key case with a screw-
d river. Direct contact with har d
o bjects may d amage or scratch
the smart key.
 Take precautions to prevent the
waterproof seal from bein g
d amag ed or contaminate d by
d irt.
 Do not touch the internal cir-
cuits an d terminals. This may
cause malfunctions.
 Do not apply excessive force to
the smart key when replacin g
the battery.
 Make sure the battery is in-
stalle d correctly. Confirm the di-
rection of the positive “+” si de
of the battery.To replace the smart key battery
1. Open the smart key case as shown.
1. Smart key system indicator light “ ”
1
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Smart key system
3-9
3
2. The turn signal lights flash once
and the vehicle power turns off.
TIPWhen the main switch is turned to

confirmed (the smart key is either out-
side operation range or has been
turned off), the beeper will sound for 3
seconds and the smart key system in-
dicator light will flash for 30 seconds. During this 30 seconds, the main
switch can be freely operated.
 After 30 seconds, the vehicle
power will turn off automatically.
 To turn the vehicle power off im-
mediately, push the main switch
knob four times within 2 seconds.
EAU76534
OPEN
The fuel tank cap lid and the seat can
be opened:
1. With the smart key on and within operating range, push the main
switch knob.
2. While the smart key system indi- cator light is on, turn the main
switch to “OPEN”. To open the fuel tank cap li
d
Push the “FUEL” button to open the
fuel tank cap lid.
After refueling, push the fuel tank cap
lid until it is closed.
TIP See page 6-14 for fuel tank cap re-
moval and installation procedures.To open the seat
Push the “SEAT” button, and then lift
the rear of the seat.
To close the seat, push down on the
rear to lock it in position.TIP Make sure that the seat is securely
closed before starting off.
 The seat can also be opened with
the mechanical key. (See page
6-19.)
1. Push.
2. Turn.
1. “FUEL” button1
2
1
1.
1
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Instrument and control functions
6-12
6
EAU53142
ABSThe Yamaha ABS (Anti-lock Brake
System) features a dual electronic con-
trol system, which acts on the front and
rear brakes independently.
Operate the brakes with ABS as you
would conventional brakes. If the ABS
is activated, a pulsating sensation may
be felt at the brake levers. In this situa-
tion, continue to apply the brakes and
let the ABS work; do not “pump” the
brakes as this will reduce braking ef-
fectiveness.
WARNING
EWA16051
Always keep a sufficient d istance
from the vehicle ahead to match the
ri din g speed even with ABS.
 The ABS performs best with
lon g b rakin g d istances.
 On certain surfaces, such as
rou gh or g ravel roa ds, the b rak-
in g d istance may b e longer with
the ABS than without.The ABS is monitored by an ECU,
which will revert the system to conven-
tional braking if a malfunction occurs.
TIP The ABS performs a self-diagno-
sis test each time the vehicle first
starts off after the key is turned to
“ON” and the vehicle has traveled
at a speed of 10 km/h (6 mi/h) or
higher. During this test, a “click-
ing” noise can be heard from the
front of the vehicle, and if either
brake lever is even slightly ap-
plied, a vibration can be felt at the
lever, but these do not indicate a
malfunction.
 This ABS has a test mode which
allows the owner to experience
the pulsation at the brake levers
when the ABS is operating. How-
ever, special tools are required, so
please consult your Yamaha deal-
er.NOTICE
ECA20100
Be careful not to damag e the wheel
sensor or wheel sensor rotor; other-
wise, improper performance of the
ABS will result.
1. Front wheel sensor
2. Front wheel sensor rotor
1. Rear wheel sensor
2. Rear wheel sensor rotor
2
1
1
2
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Instrument and control functions
6-15
6
To install the fuel tank cap, turn it
clockwise until the “ ” mark is facing
forward. Close the fuel tank cap lid.
WARNING
EWA10132
Make sure that the fuel tank cap is
properly installed
before ri din g.
Leakin g fuel is a fire hazar d.
EAU13213
FuelMake sure there is sufficient gasoline in
the tank.
WARNING
EWA10882
Gasoline an d gasoline vapors are
extremely flammab le. To avoid fires
an d explosions an d to re duce the
risk of injury when refueling , follow
these instructions.1. Before refueling, turn off the en- gine and be sure that no one is sit-
ting on the vehicle. Never refuel
while smoking, or while in the vi-
cinity of sparks, open flames, or
other sources of ignition such as
the pilot lights of water heaters
and clothes dryers.
2. Do not overfill the fuel tank. 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. 3. Wipe up any spilled fuel immedi-
ately. NOTICE: Immediately
wipe off spille d fuel with a clean,
d ry, soft cloth, since fuel may
d eteriorate painte d surfaces or
plastic parts.
[ECA10072]
4. Be sure to securely close the fuel tank cap.
WARNING
EWA15152
Gasoline is poisonous an d can
cause injury or death. Han dle gaso-
line with care. Never siphon gasoline
b y mouth. If you shoul d swallow
some gasoline or inhale a lot of g as-
oline vapor, or get some gasoline in
your eyes, see your doctor imme di-
1. “ ” mark
2. Fuel tank cap
1 2
1. Fuel tank filler tube
2. Maximum fuel level
1
2
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Instrument and control functions
6-18
6
NOTICE
ECA24020
Make sure that the keyhole cover is
installe d when the mechanical key is
not bein g use d.To close the seat
Push the rear of the seat down to lock
it in place.TIPMake sure that the seat is properly se-
cured before riding.
EAU37482
Helmet hold ersThe helmet holders are located under
the seat.
To secure a helmet to a helmet hol d-
er 1. Open the seat. (See page 6-17.)
2. Attach a helmet to a helmet hold- er, and then securely close the
seat. WARNING! Never ri de with
a helmet attached to the helmet
hol der, since the helmet may hit
o bjects, causin g loss of control
an d possi bly an acci dent.
[EWA10162]
To release a helmet from a helmet
hol der
Open the seat, remove the helmet from
the helmet holder, and then close the
seat.
1. Helmet holder
1
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Periodic maintenance an d a djustment
9-8
9
3. Remove the right floorboard mats
by pulling them up.
4. Remove the bolts and screw, then pull the panel outward. To install the panel
1. Place the panel in the original po-
sition, and then install the bolts
and screw.
2. Place the right floorboard mats in their original position and push
them downward to secure them.
3. Install the bolt and the quick fas- teners.
4. Install panel A.
Panel C
To remove the panel1. Remove the windshield by remov- ing the screws. 2. Remove the panel by removing
the screws.
To install the panel
1. Place the panel in the original po- sition, and then install the screws.
1. Bolt
2. Quick fastener
1. Floorboard mat1
2
1
1. Bolt
2. Screw
12
1. Windshield
2. Screw
1. Panel C
2. Screw
1
2
1
2
2
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Periodic maintenance an d a djustment
9-16
9
a
dde d to the coolant, have a
Yamaha dealer check the anti-
freeze content of the coolant as
soon as possi ble, otherwise the
effectiveness of the coolant will
b e re duce d.
[ECA10473]
6. Install the coolant reservoir cover.
7. Place the right floorboard mat in
the original position and push it
downward to secure it.
EAU33032
Chan gin g the coolant
The coolant must be changed at the in-
tervals specified in the periodic main-
tenance and lubrication chart. Have a
Yamaha dealer change the coolant.
WARNING! Never attempt to remove
the ra diator cap when the en gine is
hot.
[EWA10382] EAU67174
Air filter an
d V- belt case air fil-
ter elementsThe air filter element should be re-
placed and the V-belt case air filter el-
ement should be cleaned at the
intervals specified in the periodic main-
tenance and lubrication chart. Service
the air filter elements more frequently if
you are riding in unusually wet or dusty
areas. The air filter check hose and V-
belt case air filter check hose must be
frequently checked and cleaned if nec-
essary.
Cleanin g the air filter check hose
1. Coolant reservoir capCoolant reservoir capacity (up to
the maximum level mark):
0.13 L (0.14 US qt, 0.11 Imp.qt)
1
1. Air filter check hose
1
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