engine YAMAHA BIG BEAR PRO 400 2003 Workshop Manual

8-47
8. Reinstall the element to the element guide.
9. Reinstall the element assembly and parts re-
moved for access.NOTE:The air filter element should be cleaned every 20 ~
40 hours. It should be cleaned and lubricated more
often if the machine is operated in extremely dusty
areas. Each time filter element maintenance is
performed, check the air inlet to the filter case for
obstructions. Check the air cleaner rubber joint to
the carburetor and manifold fittings for an air-tight
seal. Tighten all fittings securely to avoid the pos-
sibility of unfiltered air entering the engine.CAUTION:
Never operate the engine with the air filter ele-
ment removed. This will allow unfiltered air to
enter, causing rapid engine wear and possible
engine damage. Additionally, operation with-
out the filter element will affect carburetor jet-
ting with subsequent poor performance and
possible engine overheating.
EE.book Page 47 Monday, June 18, 2001 10:18 AM

8-49
EBU00296
Carburetor adjustment
The carburetor is a vital part of the engine and re-
quires very sophisticated adjustment. Most adjust-
ing should be left to a Yamaha dealer who has the
professional knowledge and experience to do so.
However, the idling speed may be performed by
the owner as a part of the usual maintenance rou-
tine.CAUTION:
The carburetor was set at the Yamaha factory
after many tests. If the settings are disturbed
by someone without sufficient technical
knowledge, poor engine performance and
damage may result.
EE.book Page 49 Monday, June 18, 2001 10:18 AM

8-51 1. Throttle stop screw
1. Vis d’arrêt de l’accélérateur
1. Tornillo de tope del acelerador
EBU00301
Idle speed adjustmentNOTE:A diagnostic tachometer must be used for this pro-
cedure.1. Start the engine and warm it up for a few min-
utes at approximately 1,000 to 2,000 r/min.
Occasionally rev the engine to 4,000 to
5,000 r/min. The engine is warm when it
quickly responds to the throttle.
2. Connect the tachometer and set the idle to
the specified idling speed by adjusting the
throttle stop screw. Turn the screw in to in-
crease engine speed, and out to decrease
engine speed.
Specified idle speed:
1,350 ~ 1,450 r/min
EE.book Page 51 Monday, June 18, 2001 10:18 AM

8-53 1. Locknut 2. Adjuster
1. Contre-écrou 2. Dispositif de réglage
1. Contratuerca 2. Ajustador
EBU00303
Valve clearance adjustment
The correct valve clearance changes with use, re-
sulting in improper fuel/air supply or engine noise.
To prevent this, the valve clearance must be ad-
justed regularly. This adjustment however, should
be left to a professional Yamaha service techni-
cian.
EBU00305
Select lever safety system cable adjustment
The select lever safety system cable stretches
with use, resulting in improper function.
To prevent this, the cable must be adjusted regu-
larly. This adjustment, however, should be left to a
Yamaha dealer.
EE.book Page 53 Monday, June 18, 2001 10:18 AM

8-55 1. Adjusting bolt 2. Locknut a. 3 ~ 5 mm
1. Bouchon de réglage 2. Contre-écrou
1. Perno de ajuste 2. Contratuerca
1. Brake pad a. Wear limit: 1 mm
1. Plaquette de frein a. Limite d’usure: 1 mm
1. Pastillas del freno a. Límite de desgaste: 1 mm
EBU00307
Throttle lever adjustmentNOTE:Adjust the engine idling speed before adjusting the
throttle lever free play.1. Loosen the locknut.
2. Turn the adjusting bolt until the throttle lever
free play is 3 ~ 5 mm.
3. Tighten the locknut.
EBU00312
Front brake pad inspection
Inspect the brake pads for damage and wear. If
the thickness is less than the specified value, have
a Yamaha dealer replace the pads.NOTE:The wheels need to be removed to inspect the
brake pads. See page 8-81 for removal proce-
dures.
EE.book Page 55 Monday, June 18, 2001 10:18 AM

8-79
EBU00570
Cable inspection and lubrication
WARNING
Inspect cables frequently and replace if dam-
aged. Corrosion can result when the outer cov-
ering of control cables becomes damaged.
Cables can also become frayed or kinked. Op-
eration of controls could be restricted, which
could cause an accident or injury.Lubricate the inner cables and the cable ends. If
the cables do not operate smoothly, ask a Yamaha
dealer to replace them.
EBU00652
Brake and shift pedal/brake lever lubrication
Lubricate the pivoting parts of each lever and ped-
al.Recommended lubricant:
Engine oil
Recommended lubricant:
Engine oil
EE.book Page 79 Monday, June 18, 2001 10:18 AM

8-99
EBU00440Troubleshooting chart1. Fuel
Check if there is fuel
in the fuel tank.There is fuel.Turn the fuel
cock to “OFF”.Remove the fuel pipe
from the fuel cock. Fuel cock
clogged.
Clean fuel
cock. Some fuel.Turn the fuel
cock to “RES”.Restart engine.
No fuel.
Supply fuel
2. Compression
Use electric starter
to see if there is
compression.There is compression.
No compression.
3. Ignition
Remove plug and
check electrodes.WetWipe clean with
dry cloth.
DryAttach plug cap and
ground to chassis.Use the
electric starter.Spark good.Ignition system
normal.
Spark weak.
Adjust plug gap
or replace plug. No spark.
Ask a Yamaha dealer to inspect. 4. Battery
Use electric starter.Engine turns over
quickly.Battery good.
Engine turns over
slowly.
Check fuel
flow. Turn the fuel
cock to “ON”.
Compression normal.Ask a Yamaha dealer to inspect.
Recharge, check
connections.
No fuel.
EE.book Page 99 Monday, June 18, 2001 10:18 AM

9-1
EBU00420
1-CLEANING AND STORAGE
A. CLEANING
Frequent, thorough cleaning of your machine will
not only enhance its appearance but will improve
its general performance and extend the useful life
of many components.
1. Before cleaning the machine:
a. Block off the end of the exhaust pipe to pre-
vent water entry. A plastic bag and strong
rubber band may be used.
b. Make sure the spark plug and all filler caps
are properly installed.
2. If the engine case is excessively greasy, ap-
ply degreaser with a paint brush. Do not ap-
ply degreaser to the wheel axles.
3. Rinse the dirt and degreaser off with a garden
hose. Use only enough pressure to do the
job.
EE.book Page 1 Monday, June 18, 2001 10:18 AM

9-5
7. Automotive type wax may be applied to all
painted and chrome plated surfaces. Avoid
combination cleaner-waxes. Many contain
abrasives which may mar the paint or protec-
tive finish.
When finished, start the engine and let it idle
for several minutes.
WARNING
Wet brakes may have reduced stopping ability,
increasing the chance of an accident. Test the
brakes after washing. Apply the brakes several
times at slow speeds to let friction dry out the
linings.
EE.book Page 5 Monday, June 18, 2001 10:18 AM

9-7
EBU00427
B. STORAGE
Long term storage (60 days or more) of your ma-
chine will require some preventive procedures to
guard against deterioration. After thoroughly
cleaning the machine, prepare for storage as fol-
lows:
1. Fill the fuel tank with fresh fuel and add fuel
stabilizer (if available).NOTE:Use of fuel stabilizer eliminates the need to drain
the fuel system. Consult a Yamaha dealer if the
fuel system is to be drained instead.2. Remove the spark plug, pour about one ta-
blespoon of SAE 10W30 or 20W40 motor oil
in the spark plug hole and reinstall the spark
plug. Ground the spark plug wire and turn the
engine over several times to coat the cylinder
wall with oil.
3. Lubricate all control cables.
4. Block up the frame to raise all wheels off the
ground.
EE.book Page 7 Monday, June 18, 2001 10:18 AM