2003 YAMAHA BIG BEAR PRO 400 engine

7-7
Riding your ATV requires skills acquired
through practice over a period of time.
Take the time to learn the basic techniques well
before attempting more difficult maneuvers.
Not recommended for children under 16 years
of age.
WARNING
_ A child under 16 should never operate an ATV
with engine size greater than 90cc. Use by chil-
dren of ATVs that are not recommended for
their age can lead to severe injury or death of
the child. _
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7-35
Select a large, flat area off-road to become familiar
with your ATV. Make sure that this area is free of
obstacles and other riders. You should practice
control of the throttle, brakes, shifting procedures,
and turning techniques in this area before trying
more difficult terrain. Always avoid riding on paved
surfaces: the ATV is designed for off-road use
only, and handling maneuvers are more difficult to
perform on pavement.
Set the parking brake and follow the instruction on
page 6-3 to start the engine. Once it has warmed
up you are ready to begin riding your ATV. As you
get on the ATV, be sure not to accidentally move
the shift pedal. Remember that the engine and ex-
haust pipe will be hot when riding and afterwards;
do not allow skin or clothing to come in contact
with these components.
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7-37
With the engine idling, lift the shift pedal to the 1st
gear position and then release the parking brake.
Apply the throttle slowly and smoothly. The centrif-
ugal clutch will engage and you will start to accel-
erate. Once the ATV has attained adequate
speed, release the throttle and lift the shift pedal to
the 2nd gear position. Release the shift pedal and
apply the throttle smoothly. Use this same proce-
dure as you move into the higher gears. Be sure to
coordinate the use of the throttle and shift pedal
properly. If the throttle is applied too abruptly or if
the throttle is not released during shifting, or if the
shift pedal is not released before applying the
throttle, the front wheels may lift off the ground re-
sulting in a loss of directional control. Avoid higher
speeds until you are thoroughly familiar with the
operation of your ATV.CAUTION:_ Do not shift gears without releasing the throt-
tle. Damage to the engine or drive train may oc-
cur. _
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7-39
When slowing down or stopping, release the throt-
tle and apply the brakes smoothly and evenly. As
you slow down, shift to a lower gear. Be sure that
the engine has sufficiently slowed before engaging
a lower gear. Improper use of the brakes or shift-
ing can cause the tires to lose traction, reducing
control and increasing the possibility of an acci-
dent.
WARNING
_ Make sure the engine has sufficiently slowed
before shifting to a lower gear. Engaging a low-
er gear when the engine speed is too high
could cause the wheels to stop rotating. _
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7-57
RIDING DOWNHILL
When riding your ATV downhill, shift your weight
as far to the rear and uphill side of the ATV as pos-
sible. Move back on the seat and sit with your
arms straight. Choose a low gear which will allow
the engine compression to do most of the braking
for you. Improper braking may cause a loss of trac-
tion.
Use caution while descending a hill with loose or
slippery surfaces. Braking ability and traction may
be adversely affected by these surfaces. Improper
braking may also cause a loss of traction.
Whenever possible, ride your ATV straight down-
hill. Avoid sharp angles which could allow the ATV
to tip or roll over. Carefully choose your path and
ride no faster than you will be able to react to ob-
stacles which may appear.
U4SH6A.book Page 57 Thursday, May 30, 2002 1:25 PM

8-1
EBU00516
1-PERIODIC MAINTENANCE AND
ADJUSTMENTPeriodic inspection, adjustment and lubrication will
keep your machine in the safest and most efficient
condition possible. Safety is an obligation of the
machine owner. The most important points of ma-
chine inspection, adjustment and lubrication are
explained on the following pages.
WARNING
Never service an engine while it is running.
Moving parts can catch clothing or parts of the
body, causing injury. Electrical components
can cause shocks or can start fires. Turn off
the engine when performing maintenance un-
less otherwise specified. Have a Yamaha deal-
er perform service if you are not familiar with
machine service.
U4SH6A.book Page 1 Thursday, May 30, 2002 1:25 PM

8-7
EBU00262PERIODIC MAINTENANCE/LUBRICATION
ITEM ROUTINEINITIAL EVERY
1
month3
months6
months6
months1
year
Valves*•Check valve clearance.
•Adjust if necessary.Spark plug•Check condition.
•Adjust gap and clean.
•Replace if necessary.Air filter•Clean.
•Replace if necessary.Every 20–40 hours
(More often in wet or dusty areas.)
Carburetor*•Check idle speed/starter operation.
•Adjust if necessary.Crankcase breather
system*•Check breather hose for cracks or damage.
•Replace if necessary.Exhaust system*•Check for leakage.
•Retighten if necessary.
•Replace gasket(s) if necessary.Fuel line*•Check fuel hose for cracks or damage.
•Replace if necessary.Engine oil
•Replace (Warm engine before draining).Transfer gear oil
Engine oil filter
•Replace.Engine oil strainer
•Clean.Final gear oil
•Check oil level/oil leakage.
•Replace every 12 months.Differential gear oil
Front brake*•Check operation/fluid leakage/see NOTE page 8-8.
•Correct if necessary.Rear brake*•Check operation.
•Adjust if necessary.Clutch*•Check operation.
•Adjust if necessary.U4SH6A.book Page 7 Thursday, May 30, 2002 1:25 PM

8-13 1. Oil filler cap
1. Bouchon de remplissage d’huile
1. Tapa del orificio de llenado de aceite
1. Dipstick 2. Maximum level mark
3. Minimum level mark
1. Jauge 2. Repère de niveau maximum
3. Repère de niveau minimum
1. Varilla 2. Marca de nivel máximo
3. Marca de nivel minimo
EBU01233
Engine oil
Engine oil level measurement
1. Place the ATV on a level surface.
2. Warm up the engine for several minutes, and
then stop it.
3. Remove the engine oil filler cap and wipe off
the dipstick with a clean rag. Insert the dip-
stick in the filler hole without screwing it in.NOTE:_ Wait a few minutes until the oil level settles before
checking. _4. Remove the dipstick and check the oil level.
5. The oil level should be between the maxi-
mum and minimum level marks. If the engine
oil is below the minimum level mark, add the
specified amount of the specified engine oil to
raise it to the specified level.CAUTION:_ Make sure that no foreign material enters the
crankcase. _
U4SH6A.book Page 13 Thursday, May 30, 2002 1:25 PM