2021 YAMAHA GP800R engine

4-15
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EJU00552a
Cleaning and adjusting the
spark plugs
The spark plug is an important engine
component and is easy to inspect. The con-
dition of the spark plug can indicate some-
thing about the condition of the engine. For
example, if the center electrode porcelain is
very white, this could indicate an intake air
leak or carburetion problem in that cylinder.
Do not attempt to diagnose any problems
yourself. Have a Yamaha dealer service the
watercraft.
Remove and inspect the spark plug peri-
odically; heat and deposits will cause the
spark plug to slowly break down and erode.
If electrode erosion becomes excessive, or if
carbon and other deposits are excessive,
replace the spark plug with the specified
plug.
Measure the spark plug gap a with a
wire thickness gauge before installing the
spark plug. Adjust the gap to specification if
necessary.
To reinstall spark plug:
1. Clean the gasket surface.
2. Wipe any dirt from the threads of the
spark plug.
3. Screw the spark plug to the correct
torque. Standard spark plug: BR8ES
Spark plug gap:
0.7–0.8 mm (0.028–0.031 in)
Spark plug torque:
25 N·m (2.5 kgf·m, 18 ft·lb)

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EJU00573
Adjusting the carburetor
The carburetor is a vital part of the engine
and requires very sophisticated adjustment.
Most adjusting should be left to a Yamaha
dealer who has the professional knowledge
and experience to perform it. However, the
operator may adjust the trolling speed as
part of the usual maintenance routine.
CAUTION:
The carburetor was set at the Yamaha
factory after many tests. If the settings
are disturbed by someone who does not
have the necessary technical knowledge,
poor engine performance and damage
may result.
EJU00577a
Adjusting the trolling speed
1. Put the watercraft in the water.
2. Start the engine and warm it up for 1 or
2 minutes. Using a diagnostic tachome-
ter or, if necessary, the tachometer in the
multifunction information center, adjust
the engine speed to specification.
3. Turn the throttle stop screw 1 clockwise
to increase engine speed if necessary.
Turn it counterclockwise to decrease
engine speed if necessary.
Trolling speed: 1,250–1,350 r/min

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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)

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EJU00595
Troubleshooting
If you have any trouble with your watercraft, use this section to check for the possible
cause.
If you cannot find the cause, or if the procedure for replacement or repair is not described
in this Owner’s/Operator’s Manual, have a Yamaha dealer perform the necessary service.
EJU00596a
Troubleshooting chart
TROUBLE POSSIBLE CAUSE REMEDY PAGE
Engine does not
startStarter motor does not turn over
Engine shut-
off switchClip not in place Install clip
2-8
Fuse Burned out Replace the fuse and
check wiring4-22
Battery Run down Recharge 4-19
Poor terminal connec-
tionsTighten as required
4-19
Terminal corroded Clean 4-5
Starter motor Faulty Have serviced by
Yamaha dealer—
Starter motor turns over
Fuel cock Turned to “OFF” Turn the fuel cock to
“ON”2-7
Fuel Empty Refill as soon as possi-
ble3-3
Stale or contaminated Have serviced by
Yamaha dealer4-10
Fuel tank Water or dirt present Have serviced by
Yamaha dealer4-11
Spark plug Fouled or defective Clean or replace 4-15
Spark plug cap Not connected or loose Connect properly 4-15
Crankcase Filled with water Crank engine with plug
out until clean5-8
Fuel filter Clogged or water
pooledHave serviced by
Yamaha dealer4-11
Choke Choke valve can not be
closed surely by lever
operationHave serviced by
Yamaha dealer —

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Engine runs irregu-
larly or stallsFuel Empty Refill as soon as possi-
ble3-3
Stale or contaminated Have serviced by
Yamaha dealer4-10
Choke Lever is moved to on Move back to original
position2-8
Fuel filter Clogged or water
pooledHave serviced by
Yamaha dealer4-11
Fuel tank Water or dirt present Have serviced by
Yamaha dealer4-11
Spark plug Fouled or defective Replace 4-15
Incorrect heat range Replace 4-15
Gap incorrect Adjust 4-15
Spark plug cap Loose Connect properly 4-15
Cracked, torn, or dam-
agedHave serviced by
Yamaha dealer—
Electrical wir-
ingLoose connection Tighten or connect
properly—
Carburetor Incorrect idle adjust-
mentAdjust idle
4-21
Clogged Have serviced by
Yamaha dealer—
Warning light or
indicator blinksFuel level Empty Refill as soon as possi-
ble3-3
Engine oil level Empty Refill immediately 3-4
Oil filter clogged Clean 4-12
Engine over-
heatedJet intake clogged Clean
5-4
Low battery
voltageBattery voltage low Charge 4-19
Battery terminal con-
nected wrongConnect properly
4-19 TROUBLE POSSIBLE CAUSE REMEDY PAGE

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Wate rcr af t slow or
loses powerCavitation Jet intake clogged Clean 5-4
Impeller damaged or
wornHave serviced by
Yamaha dealer—
Engine over-
heatedJet intake clogged Clean
5-4
Fuel filter Clogged Have serviced by
Yamaha dealer4-11
Spark plug Fouled or defective Replace 4-15
Incorrect heat range Replace 4-15
Gap incorrect Adjust 4-15
Spark plug
capsLoose Connect properly
4-15
Electrical wir-
ingLoose connection Tighten or connect
properly—
Fuel Stale or contaminated Have serviced by
Yamaha dealer4-10
Bilge Water in bilge Drain 3-7 TROUBLE POSSIBLE CAUSE REMEDY PAGE

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EJU00597
Emergency procedures
EJU00598
Cleaning the jet intake and
impeller
If weeds or debris get caught in the intake
or impeller, cavitation can occur, causing jet
thrust to decrease even though engine
speed rises. If this condition is allowed to
continue, the engine will overheat and may
seize. If there is any sign that the jet intake
or impeller is clogged with weeds or debris,
beach the watercraft and check the intake
and impeller. Always stop the engine before
beaching the watercraft.
WARNING
Before attempting to remove weeds or
debris from the jet intake or impeller
areas, shut the engine off and remove
the clip from the engine shut-off switch.
Severe injury or death could result from
contact with the rotating parts of the jet
pump.
1. Turn the watercraft on its side as shown.
CAUTION:
●Place a suitable clean cloth or carpet-
ing underneath the watercraft to pro-
tect it from abrasions and scratches.
●Always turn the watercraft over onto
its port (left) side.
●When turning the watercraft on its
side, support the bow so the handle-
bars cannot be bent or damaged.

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2. Remove any weeds or debris from
around the drive shaft, impeller, pump
housing, and jet thrust nozzle.
If debris is difficult to remove, consult
your Yamaha dealer.
CAUTION:
Always avoid operating your watercraft in
areas where weed growth is thick. If trav-
eling in weeded areas is unavoidable,
operate the engine alternately at partial
throttle and full throttle. Weeds tend to
accumulate more at a steady speed and
at trolling speed. If weeds clog the intake
or impeller area and cause cavitation, fol-
low the cleaning procedure above.
EJU00599
Jumping the battery
If the watercraft battery has run down, the
engine can be started using a 12-volt bat-
tery and jumper cables.
WARNING
Battery electrolyte is poisonous and dan-
gerous, causing severe burns, etc. Elec-
trolyte contains sulfuric acid. Avoid
contact with skin, eyes or clothing.
Antidotes
External: Flush with water.
Internal: Drink large quantities of water
or milk. Follow with milk of magnesia,
beaten egg or vegetable oil. Call physi-
cian immediately.
Eyes: Flush with water for 15 minutes
and get prompt medical attention.
Batteries give off explosive gases. Keep
sparks, flame, cigarettes, etc. well away.
If using or charging the battery in an
enclosed area, make sure that it is well
ventilated. Always shield your eyes when
working near batteries.
KEEP OUT OF THE REACH OF CHILDREN.