check engine YAMAHA NMAX 155 2021 User Guide

Operation and important ri din g points
8-2
8
EAU86741
Startin g the en gineThe ignition circuit cut-off system will
enable starting only when the side-
stand is up.
To start the engine1. Turn the main switch on.
2. Confirm the indicator and warning light(s) come on for a few sec-
onds, and then go off. (See page
6-1.)TIPDo not start the engine if the en-
gine trouble warning light remains
on.
 The ABS warning light should
come on and stay on until the ve-
hicle reaches a speed of 10 km/h
(6 mi/h).NOTICE
ECA24110
If a warnin g or in dicator li ght does
not work as d escribed a bove, have a
Yamaha dealer check the vehicle.3. Close the throttle completely.
4. While applying the front or rear
brake, push the start switch. 5. Release the start switch when the
engine starts, or after 5 seconds.
Wait 10 seconds before pressing
the switch again to allow battery
voltage to restore.
NOTICE
ECA11043
For maximum en gine life, never ac-
celerate har d when the en gine is
col d!
EAU45093
Startin g off1. While pulling the rear brake lever
with your left hand and holding the
grab bar with your right hand,
push the scooter off the center-
stand.
2. Sit astride the seat, and then ad- just the rear view mirrors.
3. Switch the turn signals on.
4. Check for oncoming traffic, and then slowly turn the throttle grip
(on the right) in order to take off.
5. Switch the turn signals off.1. Grab bar
1
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Periodic maintenance an d a djustment
9-2
9
EAU71021
TIP The annual checks must be performe d every year, except if a distance- based maintenance is performe d in-
stea d.
 From 30000 km (17500 mi), repeat the maintenance intervals starting from 6000 km (3500 mi).
 Items marked with an asterisk should be performed by a Yamaha dealer as they require special tools, data and tech-
nical skills.
EAU71041
Perio dic maintenance chart for the emission control systemNO. ITEM CHECK OR MAINTENANCE JOB ODOMETER READING
ANNUAL
CHECK
1000 km
(600 mi) 6000 km
(3500 mi) 12000 km
(7000 mi) 18000 km
(10500 mi) 24000 km
(14000 mi)
1 *Fuel line • Check fuel hoses for cracks or
damage.
• Replace if necessary. 
2 Spark plu g• Check condition.
• Adjust gap and clean.

•Replace. 
3 *Valve clearance • Check and adjust. 
4 *Fuel injection • Check engine idle speed. 
5 *Exhaust system • Check for leakage.
• Tighten if necessary.
• Replace gasket if necessary. 
6 *Evaporative emis-
sion control system • Check control system for dam-
age.
• Replace if necessary. 
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Periodic maintenance an d a djustment
9-5
9
20 En gine oil • Change (warm engine before
draining).
• Check oil level and vehicle for oil leakage. At the initial interval and when the oil change indicator flashes or
comes on. 
21 *Engine oil strainer • Clean. 
22 *Final transmission
oil • Check vehicle for oil leakage.

• Change. 
23 *Coolin g system • Check coolant level and vehicle
for coolant leakage. 
• Change. Every 3 years
24 *V-belt • Replace. When the V-belt replacement indicator flashes or comes on
25 *Front an
d rear
b rake switches • Check operation.

26 *Movin
g parts an d
cab les • Lubricate.

27 *Throttle
grip hous-
in g an d cab le • Check operation and free play.
• Adjust the throttle cable free play
if necessary.
• Lubricate the throttle grip housing and cable. 
28 *Li
ghts, si gnals an d
switches • Check operation.
• Adjust headlight beam.

NO. ITEM CHECK OR MAINTENANCE JOB
ODOMETER READING
ANNUAL
CHECK
1000 km
(600 mi) 6000 km
(3500 mi) 12000 km
(7000 mi) 1
8000 km

(10500 mi) 24000 km
(14000 mi)
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Periodic maintenance an d a djustment
9-6
9
EAU72790
TIP Engine air filter and V-belt air filter
• This model’s engine air filter is equipped with a disposable oil-coated paper element, which must not be cleaned with compressed air to avoid damaging it.
• The engine air filter element needs to be replaced and the V-belt air filter element needs to be serviced more fre-
quently when riding in unusually wet or dusty areas.
 Hydraulic brake service
• After disassembling the brake master cylinders and calipers, always change the fluid. Regularly check the brake fluid levels and fill the reservoirs as required.
• Every two years replace the internal components of the brake master cylinders and calipers, and change the brake fluid.
• Replace the brake hoses every four years and if cracked or damaged.
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Periodic maintenance an d a djustment
9-9
9 2. Install the windshield by installing
the screws.
EAU67161
Checkin g the spark plu gThe spark plug is an important engine
component, which is easy to check.
Since heat and deposits will cause any
spark plug to slowly erode, the spark
plug should be removed and checked
in accordance with the periodic main-
tenance and lubrication chart. In addi-
tion, the condition of the spark plug
can reveal the condition of the engine.
To remove the spark plu g
1. Place the vehicle on the center- stand.
2. Remove panels A and B. (See page 9-7.)
3. Remove the spark plug cap. 4. Remove the spark plug as shown,
with the spark plug wrench includ-
ed in the owner’s tool kit.
To check the spark plu g
1. Check that the porcelain insulator around the center electrode of the
spark plug is a medium-to-light
tan (the ideal color when the vehi-
cle is ridden normally).
TIPIf the spark plug shows a distinctly dif-
ferent color, the engine could be oper-
ating improperly. Do not attempt to
diagnose such problems yourself. In-
stead, have a Yamaha dealer check
the vehicle.
1. Spark plug cap
1
1. Spark plug wrench
1
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Periodic maintenance an d a djustment
9-11
9
EAU36113
CanisterThis model is equipped with a canister
to prevent the discharging of fuel vapor
into the atmosphere. Before operating
this vehicle, make sure to check the
following:
 Check each hose connection.
 Check each hose and canister for
cracks or damage. Replace if
damaged.
 Make sure that the canister
breather is not blocked, and if
necessary, clean it.
EAU66995
Engine oil an d oil strainerThe engine oil level should be checked
before each ride. In addition, the oil
must be changed and the oil strainer
cleaned at the intervals specified in the
periodic maintenance and lubrication
chart.
To check the en gine oil level
1. Place the vehicle on the center- stand. A slight tilt to the side can
result in a false reading.
2. Start the engine, warm it up for several minutes, and then turn it
off.
3. Wait a few minutes until the oil set- tles, remove the engine oil filler
cap, wipe the engine oil dipstick
clean, insert it back into the oil fill-
er hole (without screwing it in), and
then remove it again to check the
oil level. WARNING! The muffler
an d muffler protector become
very hot d uring use. To avoi d
possi ble burns, let the muffler
an d protector cool before re-
movin g the oil filler cap.
[EWA17810]
TIPThe engine oil should be between the
tip of the dipstick and the maximum
level mark.4. If the engine oil is not between the
tip of the dipstick and the maxi-
mum level mark, add sufficient oil
of the recommended type to raise
it to the correct level.
5. Insert the dipstick into the oil filler hole, and then tighten the oil filler
cap.
1. Canister
2. Canister breather
2
1
1. Oil filler hole
2. O-ring
3. Engine oil dipstick
4. Maximum level mark
5. Tip of the engine oil dipstick
3245
1
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Periodic maintenance an d a djustment
9-12
9
To chan
ge the en gine oil an d clean
the oil strainer 1. Start the engine, warm it up for several minutes, and then turn it
off.
2. Place an oil pan under the engine to collect the used oil.
3. Remove the engine oil filler cap and engine oil drain bolts A and B
to drain the oil from the crankcase.
NOTICE: When removin g the
en gine oil drain bolt B, the O-
rin g, compression sprin g, an d
oil strainer will fall out. Take
care not to lose these parts.
[ECAT1022]
4. Clean the engine oil strainer with solvent, and then check it for
damage and replace it if neces-
sary.
5. Install the engine oil strainer, com- pression spring, new O-ring and
engine oil drain bolt B.TIPMake sure that the O-ring is properly
seated.
6. Install engine oil drain bolt A andits new gasket, and then tighten
both drain bolts to their specified
torques.
7. Refill with the specified amount of the recommended engine oil, and
then install and tighten the oil filler
cap.TIPBe sure to wipe off spilled oil on any
parts after the engine and exhaust sys-
tem have cooled down.NOTICE
ECA24060
Make sure that no forei gn material
enters the crankcase.
1. Engine oil drain bolt A
2. Gasket
3. Oil strainer
4. Compression spring
5. O-ring
6. Engine oil drain bolt B
2 3
4
5
6
1
Ti ghtenin g torque:
Engine oil drain bolt A: 20 N·m (2.0 kgf·m, 15 lb·ft)
Engine oil drain bolt B:
20 N·m (2.0 kgf·m, 15 lb·ft)
Recommen ded en gine oil:
See page 11-1.
Oil quantity: 0.90 L (0.95 US qt, 0.79 Imp.qt)
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Periodic maintenance an d a djustment
9-13
9 8. Start the engine, and then let it idle
for several minutes while checking
it for oil leakage. If oil is leaking,
immediately turn the engine off
and check for the cause.
9. Turn the engine off, and then check the oil level and correct it if
necessary.
10. Reset the oil change tripmeter and oil change indicator “OIL”. (See
page 6-8 for reset procedures.)
EAU85450
Why Yamalu beYAMALUBE oil is a Genuine YAMAHA
Part born of the engineers’ passion
and belief that engine oil is an impor-
tant liquid engine component. We form
teams of specialists in the fields of me-
chanical engineering, chemistry, elec-
tronics and track testing, and have
them develop the engine together with
the oil it will use. Yamalube oils take full
advantage of the base oil’s qualities
and blend in the ideal balance of addi-
tives to make sure the final oil clears
our performance standards. Thus,
Yamalube mineral, semisynthetic and synthetic oils have their own distinct
characters and value. Yamaha’s expe-
rience gained over many years of re-
search and development into oil since
the 1960’s helps make Yamalube the
best choice for your Yamaha engine.
EAU67822
Final transmission oilThe final transmission case must be
checked for oil leakage before each
ride. If any leakage is found, have a
Yamaha dealer check and repair your motorcycle. In addition, the final trans-
mission oil must be changed as follows
at the intervals specified in the periodic
maintenance and lubrication chart. 1. Start the engine and warm up the final transmission oil by riding the
motorcycle for several minutes.
2. Stop the engine and then place the motorcycle on the center-
stand.
3. Place an oil pan under the final transmission case to collect the
used oil.
4. Remove the final transmission oil filler cap and its O-ring from the fi-
nal transmission case.
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Periodic maintenance an d a djustment
9-15
9
EAU20071
CoolantThe coolant level should be checked
before each ride. In addition, the cool-
ant must be changed at the intervals
specified in the periodic maintenance
and lubrication chart.
EAUN2930
To check the coolant level
1. Place the vehicle on the center- stand.TIPThe coolant level must be
checked on a cold engine since
the level varies with engine tem-
perature.
 Make sure that the vehicle is posi-
tioned straight up when checking
the coolant level. A slight tilt to the
side can result in a false reading.2. Check the coolant level in the
coolant reservoir.TIPThe coolant should be between the
minimum and maximum level marks.
3. If the coolant is at or below theminimum level mark, remove the
right floorboard mat by pulling it
up.
4. Remove the coolant reservoir cov- er. 5. Remove the coolant reservoir cap,
add coolant to the maximum level
mark, and then install the reservoir
cap. WARNING! Remove only
the coolant reservoir cap. Never
attempt to remove the ra diator
cap when the en gine is hot.
[EWA15162]
NOTICE: If coolant is not
availa ble, use d istilled water or
soft tap water instea d. Do not
use har d water or salt water
since it is harmful to the en gine.
If water has been used instead
of coolant, replace it with cool-
ant as soon as possi ble, other-
wise the coolin g system will not
b e protecte d a gainst frost an d
corrosion. If water has been
1. Maximum level mark
2. Minimum level mark
1. Floorboard mat
1
2
1
1. Coolant reservoir cover
1
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Periodic maintenance an d a djustment
9-19
9
EAU21386
Checkin g the throttle grip free
playMeasure the throttle grip free play as
shown.
Periodically check the throttle grip free
play and, if necessary, have a Yamaha
dealer adjust it.
EAU21403
Valve clearanceThe valves are an important engine
component, and since valve clearance
changes with use, they must be
checked and adjusted at the intervals
specified in the periodic maintenance
chart. Unadjusted valves can result in
improper air-fuel mixture, engine
noise, and eventually engine damage.
To prevent this from occurring, have
your Yamaha dealer check and adjust
the valve clearance at regular intervals.TIPThis service must be performed when
the engine is cold.
EAU69761
TiresTires are the only contact between the
vehicle and the road. Safety in all con-
ditions of riding depends on a relatively
small area of road contact. Therefore, it
is essential to maintain the tires in good
condition at all times and replace them
at the appropriate time with the speci-
fied tires.
Tire air pressure
The tire air pressure should be
checked and, if necessary, adjusted
before each ride.
WARNING
EWA10504
Operation of this vehicle with im-
proper tire pressure may cause se-
vere injury or death from loss of
control.  The tire air pressure must be
checked and a djuste d on col d
tires (i.e., when the temperature
of the tires equals the am bient
temperature).
 The tire air pressure must be
a d juste d in accor dance with the
ri din g speed and with the total
1. Throttle grip free playThrottle g rip free play:
3.0–5.0 mm (0.12–0.20 in)
1
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