2004 YAMAHA BIG BEAR PRO 400 engine

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.
U4SH6B.book Page 35 Tuesday, May 27, 2003 4:39 PM

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. _
U4SH6B.book Page 39 Tuesday, May 27, 2003 4:39 PM

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.
U4SH6B.book Page 57 Tuesday, May 27, 2003 4:39 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.
U4SH6B.book Page 1 Tuesday, May 27, 2003 4:39 PM

8-7
EBU00262
PERIODIC MAINTENANCE/LUBRICATION
ITEM ROUTINEINITIAL EVERY
1
month3
months6
months6
months1
year
Valves*Check valve clearance.
Adjust if necessary.Spark plugCheck condition.
Adjust gap and clean.
Replace if necessary.Air filter elementClean.
Replace if necessary.Every 20–40 hours
(More often in wet or dusty areas.)
Carburetor*Check starter (choke) operation.
Adjust engine idling speed.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 element
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.U4SH6B.book Page 7 Tuesday, May 27, 2003 4:39 PM

8-13 1. Engine oil filler cap
1. Bouchon de remplissage d’huile de moteur
1. Tapa del orificio de llenado de aceite de motor
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
EBU12332
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 minimum
and maximum level marks. If the engine oil is
below the minimum level mark, add sufficient
oil of the recommended type to raise it to the
correct level.CAUTION:_ Make sure that no foreign material enters the
crankcase. _
U4SH6B.book Page 13 Tuesday, May 27, 2003 4:39 PM

8-15 1. Clamp
1. Bride
1. Mordaza
1. Drain bolt (engine oil) 2. O-ring
3. Compression spring 4. Oil strainer
1. Boulon de vidange (huile de moteur) 2. Joint torique
3. Ressort de compression 4. Crépine à huile
1. Perno de drenaje (aceite del motor) 2. Junta tórica
3. Muelle de compresión 4. Colador de aceite
Engine oil replacement and oil filter cleaning
1. Place the ATV on a level surface.
2. Warm up the engine for several minutes, and
then stop it.
3. Place a container under the engine to collect
the used oil.
4. Remove the clamp by removing the screw.
5. Remove the engine oil filler cap and drain bolt
to drain the oil.CAUTION:_ When removing the drain bolt, the compres-
sion spring, oil strainer and O-ring will fall out.
Take care not to lose these parts. _
U4SH6B.book Page 15 Tuesday, May 27, 2003 4:39 PM