engine YAMAHA BIG BEAR PRO 400 2003 Service Manual

8-7
EBL00262PERIODIC 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.EE.book Page 7 Monday, June 18, 2001 10:18 AM

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
EBU00824
Engine oil
Engine oil level measurement
1. Place the machine on a level place.
2. Warm up the engine for several minutes and
stop it.
3. Remove the oil filler cap and wipe the dipstick
off with a clean rag. Insert the dipstick 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 inspect the oil level.
5. The oil level should be between the maxi-
mum and minimum marks. If the level is low,
add oil to raise it to the proper level.CAUTION:_ Be sure no foreign material enters the crank-
case. _
EE.book Page 13 Monday, June 18, 2001 10:18 AM

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 machine on a level place.
2. Warm up the engine for several minutes and
stop it.
3. Place a container under the engine to collect
the used oil.
4. Remove the clamp.
5. Remove the 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. _
EE.book Page 15 Monday, June 18, 2001 10:18 AM

8-17 1. Filter cover bolt (× 3)
2. Oil filter cover
1. Boulon de couvercle de filtre (× 3)
2. Couvercle du filtre à huile
1. Perno de la tapa del filtro (× 3)
2. Tapa del filtro de aceite
1. Oil filter 2. O-ring (× 2)
1. Filtre à huile 2. Joint torique (× 2)
1. Filtro de aceite 2. Junta tórica (× 2)
6. Remove the shift pedal.
7. Remove the oil filter cover and oil filter.
8. Clean the oil strainer and oil filter with solvent.
9. Inspect the O-ring and replace it if damaged.
10. Install the oil filter, O-ring, oil filter cover, com-
pression spring, oil strainer and drain bolt.
Tighten the drain bolt to the specified torque.CAUTION:_ Before installing the drain bolt, be sure to in-
stall the O-ring, compression spring and oil
strainer. _
Tightening torque:
Drain bolt (engine):
32 Nm (3.2 m·kgf)
Filter cover bolt:
10 Nm (1.0 m·kgf)
EE.book Page 17 Monday, June 18, 2001 10:18 AM

8-19
11. Fill the engine with oil and install the oil filler
cap.CAUTION:_ Be sure no foreign material enters the crank-
case. _12. Warm up the engine for several minutes at
idle speed. Check for oil leakage while warm-
ing up.CAUTION:_ If oil leakage is found, stop the engine immedi-
ately and check for the cause. _
Recommended oil: See page 10-2.
Oil quantity:
Periodic oil change:
2.4 L
With oil filter replacement:
2.5 L
Total amount:
3.4 L
EE.book Page 19 Monday, June 18, 2001 10:18 AM

8-21 1. Oil gallery bolt 2. Cloth
1. Boulon de rampe de graissage 2. Chiffon
1. Perno del conducto de aceite 2. Trapo
Oil pressure check
1. Put a cloth around the cylinder.
2. Slightly loosen the oil gallery bolt in the cylin-
der head.
3. Start the engine and keep it idling until oil be-
gins to seep from the oil gallery. If no oil
comes out after one minute, turn the engine
off so it will not seize and check for the cause.
4. Restart the engine and check the oil pres-
sure.
5. After checking, tighten the oil gallery bolt to
specification.CAUTION:_ Be sure to inspect the oil pressure after replac-
ing the engine oil. _6. Install the clamp.Tightening torque:
Oil gallery bolt:
7 Nm (0.7 m·kgf)
EE.book Page 21 Monday, June 18, 2001 10:18 AM

8-23 1. Bolt (× 3)
1. Boulon (× 3)
1. Perno (× 3)
1. Oil filler bolt
1. Boulon de l’orifice de remplissage
1. Perno del orificio de llenado
EBU00462
Transfer gear oil replacementNOTE:When replacing the transfer gear oil, replace the
engine oil also.1. Remove the transfer gear case guard.
2. Place the machine on a level place.
3. Place a container under the transfer gear
case.
4. Remove the oil filler bolt and drain bolt to
drain the oil.
5. Install the drain bolt and tighten to specifica-
tion.
Tightening torque:
Drain bolt (transfer gear case):
20 Nm (2.0 m·kgf)
EE.book Page 23 Monday, June 18, 2001 10:18 AM

8-25 1. Drain bolt
1. Boulon de vidange
1. Perno de drenaje
6. Fill the transfer gear case with oil.CAUTION:
Be sure no foreign material enters the transfer
gear case.7. Install the filler bolt and tighten to specifica-
tion.
8. Check for oil leakage. If oil leakage is found,
check for the cause.
9. Reinstall the transfer gear case guard.Recommended oil: See page 10-2
Quantity:
Transfer gear oil and engine oil with
filter replacement:
2.8 L
Tightening torque:
Filler bolt (transfer gear case):
23 Nm (2.3 m·kgf)
EE.book Page 25 Monday, June 18, 2001 10:18 AM

8-37 1. Spark plug cap
1. Capuchon de bougie
1. Tapa de bujía
1. Spark plug wrench
1. Clé à bougie
1. Llave de bujías
EBU00680
Spark plug inspection
Removal
1. Remove the spark plug cap.
2. Use the spark plug wrench in the tool kit to re-
move the spark plug as shown.
Inspection
The spark plug is an important engine component
and is easy to inspect. The condition of the spark
plug can indicate the condition of the engine.
The ideal color on the white insulator around the
center electrode is a medium-to-light tan color for a
ATV that is being ridden normally.
Do not attempt to diagnose such problems your-
self. Instead, take the ATV to a Yamaha dealer.
You should periodically remove and inspect the
spark plug because 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, you should re-
place the spark plug with the specified plug.
Specified spark plug:
DR8EA (NGK)
EE.book Page 37 Monday, June 18, 2001 10:18 AM

8-45 1. Air filter element
1.Élément du filtre à air
1. Elemento filtrante
1. Element plate 2. Air filter element
3. Guide
1. Plaque d’élément 2.Élément du filtre à air
3. Guide
1. Placa del elemento 2. Elemento filtrante
3. Guía
3. Remove the air filter element, and separate it
from the guide.
4. Wash the element gently but thoroughly in
solvent.
WARNING
Always use parts cleaning solvent to clean the
air filter element. Never use low flash point sol-
vents or gasoline to clean the air filter element
because the engine could catch fire or ex-
plode.5. Squeeze the excess solvent out of the filter
and let it dry.CAUTION:
Do not twist the filter element when squeezing
it.6. Inspect the element. If damaged, replace it.
7. Apply SAE10W30 motor oil to the element.NOTE:The element should be wet but not dripping.
EE.book Page 45 Monday, June 18, 2001 10:18 AM