water pump YAMAHA GP800R 2021 Owners Manual

1-14
E
EJU00315a
Watercraft characteristics
●Jet thrust turns the watercraft. Releasing
the throttle completely produces only min-
imum thrust. If you are traveling at speeds
above trolling, you will have rapidly
decreasing ability to steer without throttle.
You may still have some turning ability
immediately after releasing the throttle,
but once the engine slows down, the
watercraft will no longer respond to han-
dlebar input until you open the throttle
again or you reach a trolling speed. Prac-
tice turning in an open area without
obstructions until you have a good feel for
this maneuver.
●This watercraft are water-jet propelled.
The jet pump is directly connected to the
engine. This means that jet thrust will pro-
duce some movement whenever the
engine is running. There is no “neutral”
position.
●Keep away from intake grate 1 while the
engine is on. Items such as long hair,
loose clothing, or PFD straps can become
entangled in moving parts resulting in
severe injury or drowning.
●Never insert any object into the jet thrust
nozzle 2 while the engine is running.
Severe injury or death could result from
coming in contact with the rotating parts
of the jet pump.
●Stop the engine and remove the clip 3
from the engine shut-off switch 4 before
removing any debris or weeds, which may
have collected around the jet intake.

2-13
E
EJU00366
Engine overheat warning
system
This model is equipped with an engine
overheat warning system.
If the engine starts to overheat, the warn-
ing light and the engine overheat warning
indicator begin to blink, the buzzer sounds,
and the engine speed will be limited to about
3,400 r/min.
When this occurs, check for water dis-
charge at the cooling water pilot outlet. If
there is no discharge of water, reduce the
engine speed and beach the watercraft, and
then check the intake grate and impeller for
clogging.
WARNING
Before attempting to remove weeds or
debris from the intake grate or impeller,
shut the engine off and remove the clip
from the engine shut-off switch. Severe
injury or death could result from coming
in contact with the rotating parts of the
jet pump.
CAUTION:
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
engine damage.
NOTE:
Press the reset button on the multifunction
information center to stop the buzzer.

3-11
E
EJU00451a
Jet unit
Carefully check the jet intake for weeds,
debris, or anything else that might restrict
the intake of water. If the intake is clogged,
cavitation could occur, reducing jet thrust,
and possibly damaging the jet pump.
In some cases, the engine may overheat
because of lack of cooling water, and dam-
age to the engine could result. Engine cool-
ing water is fed to the engine by the jet
pump. (See page 5-4 for jet intake cleaning
procedures.)
WARNING
●Keep away from intake grate while
engine is on. Items such as long hair,
loose clothing, or PFD straps can
become entangled in moving parts
resulting in severe injury or drowning.
●Stop the engine and remove the clip
from the engine shut-off switch before
removing any debris or weeds, which
may have collected around the jet
intake.
EJU00004n
Engine shut-off cord (lanyard)
Check that the engine shut-off cord is not
frayed or broken. If the cord is damaged,
replace it; never try to repair it or tie it
together.

3-17
E
5. While lightly squeezing the throttle lever,
push the start switch (green button).
WARNING
On this watercraft, the engine is con-
nected directly to the jet pump. Starting
the engine immediately generates some
thrust. Apply only enough throttle to
keep the engine running.
6. Release the start switch as soon as the
engine starts to run.
CAUTION:
●Never push the start switch while the
engine is running.
●Do not operate the start switch for
more than 5 seconds, otherwise the
battery will be discharged and the
engine will not start. Also, the starter
motor may be damaged. If the engine
does not start in 5 seconds, release
the start switch, wait 15 seconds, and
try again.
7. After the engine has warmed up, move
the choke lever back to its original posi-
tion.
NOTE:
If the choke lever is left turned on, the
engine will stall.

3-27
E
EJU00499
Turning the watercraft
Steering control depends on the combi-
nation of handlebar position and the amount
of throttle.
Water sucked in through the intake grate
is pressurized by the impeller in the jet
pump. As the pressurized water is expelled
from the pump through the jet thrust nozzle,
it creates thrust to move and steer the
watercraft. The higher the engine speed, the
more thrust is produced.
The amount of jet thrust, in addition to the
position of the handlebars, determines how
sharply you turn.
A. More throttle produces higher thrust, so
the watercraft will turn more sharply.
B. Less throttle produces lower thrust, so
the watercraft will turn more gradually.
C. Releasing the throttle completely pro-
duces only minimum thrust. If you are
traveling at speeds above trolling, you
will have rapidly decreasing ability to
steer without throttle. You may still have
some turning ability immediately after
releasing the throttle, but once the
engine slows down, the watercraft will no
longer respond to handlebar input until
you apply throttle again or you reach a
trolling speed.
At trolling speed, the watercraft can be
turned gradually by handlebar position
alone using just the amount of thrust
available at idle.
D. If the engine is stopped while riding,
there is no thrust. The watercraft will go
straight even though the handlebars are
turned.
You need throttle to steer.

E
4
EJU00515
MAINTENANCE AND
CARE
Storage....................................................... 4-1
Flushing the cooling system ................... 4-1
Lubrication............................................... 4-3
Fuel system............................................. 4-4
Battery ..................................................... 4-5
Cleaning the watercraft........................... 4-6
Maintenance and adjustments............... 4-7
Owner’s/Operator’s Manual and tool
kit ............................................................. 4-8
Periodic maintenance chart .................... 4-9
Inspecting the fuel system .................... 4-10
Inspecting the oil injection system........ 4-12
Inspecting the steering cable................ 4-13
Inspecting and adjusting the throttle
cable ...................................................... 4-13
Inspecting the QSTS mechanism ........ 4-14
Cleaning and adjusting the spark
plugs ...................................................... 4-15
Lubrication points .................................. 4-16
Inspecting the battery ........................... 4-19
Adjusting the carburetor ....................... 4-21
Replacing the fuse ................................ 4-22
Bleeding the oil injection pump............. 4-22
Adjusting the Yamaha Adjustable
Sponson (Y.A.S.) .................................. 4-23
Specifications......................................... 4-24

4-10
E
EJU00537
Inspecting the fuel system
WARNING
Gasoline and its vapors are highly flam-
mable and explosive.
Check the fuel system for leaks, cracks,
or malfunctions. If any problem is found, do
the necessary repair or replacement as
required. If repair is necessary, consult a
Yamaha dealer.
Check:
●Carburetor for leakage.
●Fuel pump for malfunction or leakage.
●Fuel tank for water or dirt.
●Fuel tank for damage, cracks or leakage.
●Fuel hose joint for leakage.
●Fuel hose for cracks or other damage.
●Fuel filter for leakage.
●Fuel cock for leakage.
●Air vent check valve for leakage.
●Fuel tank filler cap for damage.
WARNING
Failure to check for and repair any fuel
leakage may result in fire or explosion.

4-12
E
EJU00544
Inspecting the oil injection
system
Check the oil injection system for leakage,
cracks, or malfunctions. If necessary, have a
Yamaha dealer repair the oil injection sys-
tem.
Check:
●Oil tank for damage, cracks or leakage.
●Oil tank for water or dirt.
●Oil hose and joint for damage or cracks.
●Oil filter for dirt.
●Oil pump for leakage.
Oil tank
Check the oil tank for leakage or water in
the tank. If water is found in the oil injection
system or if the oil tank needs to be cleaned
have a Yamaha dealer service the water-
craft.
Oil filter
Check the oil filter 1 for dirt and clogs. If
the oil filter is clogged, remove it from the oil
tank together with the oil level sender and
clean it.

4-16
E
NOTE:
●Wipe off any water on the spark plug or
inside the cap before installing the spark
plug cap. Push the spark plug cap down
until it clicks.
●If a torque wrench is not available when
you are fitting a new spark plug, a good
estimate of the correct torque is 1/4 turn
to 1/2 turn past finger tight. Have the
spark plug adjusted to the correct torque
with a torque wrench as soon as possible.
WARNING
Be careful not to damage the insulator
when removing or installing a spark plug.
A damaged insulator could allow sparks
to escape, which could lead to explosion
or fire.
EJU00553a
Lubrication points
To keep moving parts sliding or rotating
smoothly, coat them with water-resistant
grease.
Recommended water resistant grease:
Yamaha Marine Grease/
Yamaha Grease A
●Throttle cable (carburetor end)
●Oil pump cable
●Choke cable (carburetor end)

4-24
E
EJU00588
Specifications
MODEL
ITEMUnit GP800R
WATERCRAFT CAPACITY
Maximum people on board Number of people 2
Maximum load capacity kg (lb) 160 (353)
DIMENSIONS
Length mm (in) 2,930 (115.4)
Width mm (in) 1,150 (45.3)
Height mm (in) 1,020 (40.2)
Dry weight kg (lb) 268 (591)
PERFORMANCE
Maximum output kW (PS) @ r/min 88.2 (120)@ 7,000
Maximum fuel consumption L/h (US gal/h, Imp gal/h) 49.0 (12.9, 10.8)
Cruising range at full throttle hr. 1.2
Trolling speed r/min 1,250–1,350
ENGINE
Engine type 2-stroke
Number of cylinders 2
Engine displacement
cm
3 (cu in)784 (47.8)
Bore & stroke mm (in) 80.0 ×
78.0 (3.15 ×
3.07)
Compression ratio 6.6:1
Lubrication system Variable oil injection
Cooling system Water cooled
Starting system Electric starter
Ignition system Digital CDI
Spark plug BR8ES (NGK)
Spark plug gap mm (in) 0.7–0.8 (0.028–0.031)
Battery capacity V-AH 12-19
Charging system Flywheel magneto
DRIVE UNIT
Propulsion system Jet pump
Jet pump type Axial flow, single stage
Impeller rotation Counterclockwise (viewed from rear)
Transmission Direct drive from engine
Jet thrust nozzle angle Degree 23 + 23
Trim nozzle angle Degree -5, 0, 5, 10, 15
FUEL AND OIL
Recommended fuel Regular unleaded gasoline
Minimum octane rating PON
RON86
90
Recommended engine oil YAMALUBE 2-W, or an equivalent NMMA-
certified TC-W3 marine oil
Fuel tank capacity
Total L (US gal, Imp gal) 60 (15.9, 13.2)
Reserve L (US gal, Imp gal) 10 (2.6, 2.2)
Oil tank capacity L (US gal, Imp gal) 5.5 (1.45, 1.21)