
Instrument operation
25
same time, the maximum engine speed is
limited.
If the oil pressure warning is activated, imme-
diately reduce the engine speed, return to
shore, and then check the engine oil level.
(See page 33 for information on checking the
engine oil level.) If the oil level is sufficient,
have a Yamaha dealer check the watercraft.
EJU45660Engine overheat warning
If the engine temperature rises significantly,
the “WARNING” indicator light comes on.
While the engine overheat warning is activat-
ed, the maximum engine speed is limited.
If the engine overheat warning is activated,
immediately reduce the engine speed, return
to shore, and then make sure that water is
being discharged from the cooling water pilot
outlet while the engine is running. If there is
no discharge of water, stop the engine, and
then check the jet intake for clogging. (See
page 72 for information on the jet intake.)NOTICE:
If you cannot locate and correct
the cause of the overheating, consult a
Yamaha dealer. Continuing to operate at higher speeds could result in severe en-
gine damage.
[ECJ00042]
EJU45681
Check engine warning
If a sensor malfunction or a short circuit is de-
tected, the “WARNING” indicator light blinks
once for several seconds.
If the check engine warning is activated, im-
mediately reduce the engine speed, return to
shore, and have a Yamaha dealer check the
engine.
EJU45690Communication disconnecting warning
If communication disconnecting is detected,
the “WARNING” indicator light and “L-
MODE” indicator light blink.
If the communication disconnecting warning
is activated, have the watercraft serviced by
a Yamaha dealer as soon as possible.
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Equipment operation
26
EJU40336
EquipmentEJU3105AHood
The hood is removable.
Remove the hood to access the engine com-
partment.
To remove the hood:
(1) Lift the steering pole and support it withthe lock pin. (2) Turn the latch knob to the “OPEN” posi-
tion, and then pull up on the hood latch
to unlatch the hood.
(3) Grasp the hood using the handgrips pro- vided at the front and rear of the hood.
Lift the hood up and to the rear to re-
move it.
1Steering pole
1 Lock pin
1
1
1Hood latch
2 Hood latch knob
1 Handgrip
1
2
1
1
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Operation and handling requirements
31
EJU31823
Fuel requirementsEJU45582FuelEWJ00283
Gasoline and gasoline vapors are ex-
tremely flammable. To avoid fires and
explosions and to reduce the risk of in-
jury when refueling, follow these in-
structions.
Gasoline is poisonous and can cause in-
jury or death. Handle gasoline with care.
Never siphon gasoline by mouth. If you
should swallow some gasoline, inhale a
lot of gasoline vapor, or get some gaso-
line in your eyes, see your doctor imme-
diately. If gasoline spills on your skin,
wash with soap and water. If gasoline
spills on your clothing, change your
clothes.
ECJ00322
Do not use leaded gasoline. Leaded
gasoline can seriously damage the en-
gine.
Avoid getting water and contaminants in
the fuel tank. Contaminated fuel can
cause poor performance and engine
damage. Use only fresh gasoline that
has been stored in clean containers.
TIP:
This mark identifies the recommended fuel
for this watercraft as specified by European
regulation (EN228).
Check that the gasoline nozzle has the
same identifier when fueling.
Gasohol
There are two types of gasohol: gasohol con-
taining ethanol and gasohol containing meth-
anol.
Gasohol containing ethanol can be used if
the ethanol content does not exceed 10%
and the fuel meets th e minimum octane rat-
ings. E-85 is a fuel blend containing 85% eth-
anol and therefore must not be used in this
watercraft. All ethanol blends containing
more than 10% ethanol can cause fuel sys-
tem damage or engine performance prob-
lems.
Yamaha does not recommend gasohol con- taining methanol because it can cause fuel
system damage and engine performance
problems. Recommended fuel:
Regular unleaded gasoline with a
minimum octane rating of 86
(Pump octane number) = (R + M)/2
90 (Research octane number)
E5E10
UF4R71E0.book Page 31 Monday, May 10, 2021 1:14 PM

Operation and handling requirements
32
To fill the fuel tank:
(1) Before refueling, stop the engine. Do notstand or sit on the watercraft. Never refu-
el while smoking, or while in the vicinity
of sparks, open flames, or other sources
of ignition.
(2) Place the watercraft in a well-ventilated area and in a horizontal position.
(3) Remove the hood, and then ventilate the engine compartment. (See page 26 for
hood removal and installation proce-
dures.)
(4) Loosen the fuel filler cap and remove it.
(5) Slowly add fuel to the fuel tank.
(6) Stop filling when the fuel level just reach- es the bottom of the filler tube. Do not fill
up 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. Do not leave the watercraft
with a full tank in direct sunlight.
(7) Wipe up any spilled fuel immediately with a dry cloth.
(8) Securely install the hood in its original position, and then install the fuel filler cap
by tightening it until it clicks.
1Fuel filler cap
Fuel tank capacity:
19 L (5.0 US gal, 4.2 Imp.gal)
1
1Fuel tank filler tube
2 Maximum fuel level
2
1
UF4R71E0.book Page 32 Monday, May 10, 2021 1:14 PM

Operation and handling requirements
33
EJU40291
Engine oil requirementsEJU45591Engine oilECJ00282
Use only 4-stroke engine oil. Usage of 2-
stroke engine oil could result in severe en-
gine damage.
Why Yamalube
YAMALUBE oil is a Genuine YAMAHA Part
born of the engineers’ passion and belief that
engine oil is an important liquid engine com-
ponent. We form teams of specialists in the
fields of mechanical engineering, chemistry,
electronics 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 bal-
ance of additives to make sure the final oil
clears our performance standards. Thus,
Yamalube mineral, semisynthetic and syn- thetic oils have their own distinct characters
and value. Yamaha’s experience gained over
many years of research and development
into oil since the 1960’s helps make
Yamalube the best choice for your Yamaha engine. Checking the engine oil level
EWJ00341
Engine oil is extremely hot immediately af-
ter the engine is turned off. Coming in con-
tact with or getting any engine oil on your
clothes could result in burns.
ECJ00392
Do not run the engine with too much or
not enough oil in the oil tank, otherwise
the engine could be damaged.
Make sure that debris and water do not
enter the oil tank filler hole. Debris and
water in the engine oil can cause serious
engine damage.
TIP:
When checking the engine oil level on land,
the engine must be running while water is
being supplied to the cooling water pas-
sages. (See “Flushing the cooling water
passages” on page 57 for information on
supplying water.)
When checking the engine oil level on wa-
ter, moor the watercraft so that it will not
drift away.
To check the engine oil level:
(1) With the engine stopped, place the wa- tercraft in a precisely level position on
land or launch the watercraft.
(2) Look in all directions, and then start the engine. (See page 48 for information on
starting the engine.)
(3) Run the engine at idling speed for 6 min- utes or more. Run the engine an addi-
tional 5 minutes if the ambient
temperature is 20 °C (68 °F) or less.
(4) Stop the engine.
(5) Remove the hood. (See page 26 for hood removal and installation procedures.)
Recommended engine oil:
YAMALUBE 4W or 4-stroke motor oil
Recommended engine oil type: SAE 10W-30, 10W-40, 20W-40,
20W-50
Recommended engine oil grade: API SG, SH, SJ, SL
UF4R71E0.book Page 33 Monday, May 10, 2021 1:14 PM

Operation and handling requirements
34
(6) Loosen the oil tank filler cap and removeit, and then wipe the attached dipstick
clean.
(7) Screw the oil tank filler cap into the filler hole until it stops. Remove the oil tank
filler cap again and make sure that the
engine oil level is between the minimum
and maximum level marks.
(8) If the engine oil level is significantly above the maximum level mark, consult
a Yamaha dealer. If the engine oil level is
below the minimum level mark, slowly
add engine oil.
(9) Repeat steps 6–8 until the engine oil is at the proper level.
(10) Securely install the oil tank filler cap and turn it until it stops. (11) Securely install the hood in its original
position.
1Oil tank filler cap/Dipstick
1 Dipstick
2 Maximum level mark
3 Minimum level mark
1
213
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Operation and handling requirements
35
EJU40022
Draining the bilge waterECJ01302
Do not run the engine at full throttle when
bilge water remains in the engine com-
partment. The bilge water can splash into
the engine, which can result in severe
damage.
EJU44262Draining the bilge water on land
To drain the bilge water on land:
(1) Loosen the stern drain plugs and removethem.
(2) Raise the bow of the watercraft, such as by placing the watercraft on a slope, to
drain the bilge water from the engine
compartment.
(3) After the bilge water has drained from the stern drain plug holes, wipe up any re-
maining moisture in the engine compart-
ment with a dry cloth.
(4) Check that the stern drain plugs and O- rings on the plugs are not damaged and
that there is no foreign material on the
threads or O-rings on the plugs.
NOTICE: Before installing the stern
drain plugs, clean the drain plug
threads and the O-rings on the plugs
to remove any foreign materials, such
as dirt or sand. Otherwise, the stern drain plugs could be damaged, allow-
ing water to enter the engine compart-
ment. Check the O-rings on the stern
drain plugs and make sure that the
plugs are tightened securely before
launching the watercraft. Otherwise,
water may flood the engine compart-
ment and cause the watercraft to sub-
merge.
[ECJ00364]
(5) Securely install the stern drain plugs by
tightening them until they stop.
EJU40536Draining the bilge water on water
A small quantity of bilge water will remain in
the engine compartment even after the bilge
water is drained on water. To completely
drain the bilge water, remove the watercraft
from the water and drain the bilge water on
land.
Jet vacuum bilge draining system
While the watercraft is operating, bilge water
in the engine compartment is drawn in by the
vacuum that is generated in the jet pump and
discharged from the watercraft through the
jet thrust nozzle.
To drain the bilge water on water:
Operate the watercraft as straight as possible
and above planing speed for at least 2 min-
utes. NOTICE: Do not run the engine at full
throttle for at least 1 minute after the en-
gine has been restarted. Bilge water in the
1 Stern drain plug
1
1O-ring
1
UF4R71E0.book Page 35 Monday, May 10, 2021 1:14 PM
![YAMAHA SUPERJET 2021 Owners Manual Operation and handling requirements
36
engine compartment can splash into the
engine, which can result in severe dam-
age.
[ECJ00554]EJU45602
Transporting on a trailer
When transporting the watercraf YAMAHA SUPERJET 2021 Owners Manual Operation and handling requirements
36
engine compartment can splash into the
engine, which can result in severe dam-
age.
[ECJ00554]EJU45602
Transporting on a trailer
When transporting the watercraf](/manual-img/51/51248/w960_51248-42.png)
Operation and handling requirements
36
engine compartment can splash into the
engine, which can result in severe dam-
age.
[ECJ00554]EJU45602
Transporting on a trailer
When transporting the watercraft on a trailer,
secure the tie downs to the trailer through the
bow eye and stern eyes. Use a rubber shock
cord to secure the steering pole to the water-
craft.
NOTICE: Do not attach ropes or tie
downs to any part of the watercraft other
than the bow eye and stern eyes to secure
the watercraft to the trailer. Otherwise, the
watercraft may be damaged. Wrap the
ropes or tie downs with towels or rags
where they touch the body of the water-
craft to avoid scratches or damage. Do
not secure the steering pole with ropes or
tie downs and do not secure it to the trail-
er. Also, do not transport the watercraft
UF4R71E0.book Page 36 Monday, May 10, 2021 1:14 PM