check engine YAMAHA YFM50R 2007 User Guide

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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. Allow the engine compression to do most
of the braking for you. Improper braking may cause
a loss of traction.
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.
WARNING
EWB01620
Always follow proper procedures for going
down hills as described in this Owner’s Manu-
al.
Note: a special technique is required when
braking as you go down a hill.

Always check the terrain carefully before
you start down any hill.

Shift your weight backward.

Never go down a hill at high speed.

Avoid going down a hill at an angle that
would cause the ATV to lean sharply to one
side. Go straight down the hill where possi-
ble.

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7
*
Rear brake

Check operation and correct if necessary.

Check brake lever free play and adjust if neces-
sary.
√√√√√

Replace brake shoes. Whenever worn to the limit
8
*
Wheels

Check runout and for damage, and replace if nec-
essary.
√ √√√
9
*
Tires


Check tread depth and for damage, and replace if
necessary.

Check air pressure and balance, and correct if
necessary.
√ √√√
10
*
Wheel bearings


Check for looseness or damage, and replace if
necessary.
√ √√√
11
*
Drive shaft univer-
sal joint


Lubricate with lithium-soap-based grease.
√√√
12
*
Chassis fasteners


Make sure that all nuts, bolts, and screws are
properly tightened.
√√√√√
13
*
Shock absorber
assemblies


Check operation and correct if necessary.

Check for oil leakage and replace if necessary.
√√√
14
*
Knuckle shafts


Lubricate with lithium-soap-based grease.
√√√
15
*
Steering shaft


Lubricate with lithium-soap-based grease.
√√√
16
*
Steering system


Check operation and repair or replace if damaged.

Check toe-in and adjust if necessary.
√√√√√
17
*
Carburetor


Check choke operation and correct if necessary.

Check engine idling speed and adjust if neces-
sary.
√√√√
NO. ITEMCHECK OR MAINTENANCE
JOBINITIAL EVERY
Whichev-
er comes
firstmonth 1 3 6 6 12
km
(mi)320
(200)1200
(750)2400
(1500)2400
(1500)4800
(3000)
hours 20 75 150 150 300

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*
Crankcase breather
system

Check breather hose for cracks or other damage,
and replace if necessary.
√√√
19 Engine oil

Change.

Check ATV for oil leakage, and correct if neces-
sary.
√ √√√
20 Final gear oil

Change.

Check ATV for oil leakage, and correct if neces-
sary.
√√
21
*
Moving parts and
cables


Lubricate.
√√√√
22
*
Throttle lever hous-
ing and cable


Check operation and correct if necessary.

Check throttle cable free play and adjust if neces-
sary.

Lubricate throttle lever housing and cable.
√√√√√
23
*
Exhaust system


Check for leakage and replace gasket(s) if neces-
sary.

Check for looseness and tighten all screw clamps
and joints if necessary.
√√√
24 Spark arrester

Clean.
√√√
25
*
Front and rear brake
switches


Check operation and correct if necessary.
√√√√√
26
*
Battery


Check electrolyte level and specific gravity, and
correct if necessary.

Make sure that the breather hose is properly
routed.
√√√√√
NO. ITEMCHECK OR MAINTENANCE
JOBINITIAL EVERY
Whichev-
er comes
firstmonth136612
km
(mi)320
(200)1200
(750)2400
(1500)2400
(1500)4800
(3000)
hours 20 75 150 150 300

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EBU23211
Checking the spark plug
The spark plug is an important engine component,
which is easy to check. Since heat and deposits
will cause any spark plug to slowly erode, the spark
plug should be removed and checked in accor-
dance with the periodic maintenance and lubrica-
tion chart. In addition, the condition of the spark
plug can reveal the condition of the engine.
To remove the spark plug
1. Remove the spark plug cap.
2. Remove the spark plug as shown, with thespark plug wrench included in the owner’s tool
kit.
To check the spark plug
1. Check that the porcelain insulator around the
center electrode of the spark plug is a medi-
um-to-light tan (the ideal color when the ATV
is ridden normally).
NOTE:

If the spark plug shows a distinctly different color,
the engine could be operating improperly. Do not
attempt to diagnose such problems yourself. In-
stead, have a Yamaha dealer check the ATV.
1. Spark plug cap
1

1. Spark plug wrench
1

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2. Check the spark plug for electrode erosion
and excessive carbon or other deposits, and
replace it if necessary.
To install the spark plug
1. Measure the spark plug gap with a wire thick-
ness gauge and, if necessary, adjust the gap
to specification.2. Clean the surface of the spark plug gasket
and its mating surface, and then wipe off any
grime from the spark plug threads.
3. Install the spark plug with the spark plug
wrench, and then tighten it to the specified
torque.NOTE:

If a torque wrench is not available when installing
a spark plug, a good estimate of the correct torque
is 1/4–1/2 turn past finger tight. However, the spark
plug should be tightened to the specified torque as
soon as possible.
4. Install the spark plug cap.
EBU23251
Engine oil
The engine oil level should be checked before
each ride. In addition, the oil must be changed at
the intervals specified in the periodic maintenance
and lubrication chart. Specified spark plug:
NGK/CR7HSA
Spark plug gap:
0.6–0.7 mm (0.024–0.028 in)
1. Spark plug gap
Tightening torque:
Spark plug:
12.5 Nm (1.25 m·kgf, 9.0 ft·lbf)

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To check the engine oil level
1. Place the ATV on a level surface.
2. Start the engine, warm it up for several min-
utes, and then turn it off.
3. Wait a few minutes until the oil settles before
checking.
4. Remove the engine oil filler cap, and then
wipe the dipstick off with a clean rag.
5. Insert the dipstick into the filler hole (without
screwing it in), and then remove it again to
check the oil level.NOTE:

The engine oil should be between the minimum
and maximum level marks.
6. If the engine oil is at or below the minimum
level mark, add sufficient oil of the recom-
mended type to raise it to the correct level.
7. Insert the dipstick into the oil filler hole, and
then tighten the engine oil filler cap.
To change the engine oil
1. Place the ATV on a level surface.
2. Start the engine, warm it up for several min-
1. Engine oil filler cap
2. Dipstick
12

1. Maximum level mark
2. Minimum level mark
1
2

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utes, and then turn it off.
3. Place an oil pan under the engine to collect
the used oil.
4. Remove the engine oil filler cap, and then re-
move the engine oil drain bolt to drain the oil
from the crankcase.
5. Check the O-ring for damage and replace it if
necessary.
6. Install the engine oil drain bolt, and then tight-
en it to the specified torque.7. Add the specified amount of the recommend-
ed engine oil, and then install and tighten the
engine oil filler cap.CAUTION:
ECB00300

In order to prevent clutch slippage (since the
engine oil also lubricates the clutch), do not
mix any chemical additives. Do not use oils
with a diesel specification of “CD” or oils of
a higher quality than specified. In addition,
do not use oils labeled “ENERGY CONSERV-
ING II” or higher.

Make sure that no foreign material enters the
crankcase.
8. Start the engine, and then let it idle for several
1. Engine oil drain bolt
1

Tightening torque:
Engine oil drain bolt:
20 Nm (2.0 m·kgf, 14.5 ft·lbf)
Recommended oil:
See page 10-1.
Oil quantity:
0.80 L (0.85 US qt) (0.70 Imp.qt)

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minutes while checking it for oil leakage. If oil
is leaking, immediately turn the engine off and
check for the cause.
9. Turn the engine off, and then check the oil lev-
el and correct it if necessary.
EBU23403
Final gear oil
The final gear case must be checked for oil leak-
age before each ride. If any leakage is found, have
a Yamaha dealer check and repair the ATV. In ad-
dition, the final gear oil level must be checked and
the oil changed as follows at the intervals specified
in the periodic maintenance and lubrication chart.
To check the final gear oil level
1. Place the ATV on a level surface.
NOTE:

The final gear oil level must be checked on a cold
engine.
2. Remove the final gear oil filler cap, wipe the
dipstick off with a clean rag, insert it back into
the oil filler hole (without screwing it in), and
then remove it again to check the oil level.
NOTE:

The final gear oil should be between the minimum
and maximum level marks.
3. If the oil is at or below the minimum level mark,
add sufficient oil of the recommended type to
raise it to the correct level.
4. Insert the dipstick into the oil filler hole, and
then tighten the oil filler cap.
1. Final gear oil filler cap
2. Dipstick
3. Maximum level mark
4. Minimum level mark
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plode.
5. Squeeze the excess solvent out of the sponge
material and let it dry.
CAUTION:

ECB00440
Do not twist the sponge material when squeez-
ing it.
6. Check the sponge material and replace it if
damaged.
7. Apply a quality foam air filter oil to the sponge
material.
NOTE:

The sponge material should be wet but not drip-
ping.
8. Install the sponge material into the air filter el-
ement.
9. Place the air filter element in the original posi-
tion, and then hook the holder.
10. Install the air filter case cover by hooking the
holders onto the air filter case.
11. Install the panel by installing the bolts.
NOTE:

The air filter element should be cleaned every 20–
40 hours. It should be cleaned and lubricated moreoften if the ATV is operated in extremely dusty ar-
eas. Each time the air filter element maintenance
is performed, check the air inlet of the air filter case
for obstructions.
CAUTION:

ECB00460

Make sure that the air filter element is prop-
erly seated in the air filter case.

Never operate the engine with the air filter el-
ement removed. This will allow unfiltered air
to enter the engine, causing rapid engine
wear and possible engine damage. Addition-
ally, operation without the air filter element
will affect carburetor jetting with subsequent
poor performance and possible engine over-
heating.
EBU27630
Cleaning the spark arrester
Be sure the exhaust pipe and muffler are cool be-
fore cleaning the spark arrester.
1. Remove the screws.

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EBU23940
Adjusting the carburetor
The carburetor should be checked and, if neces-
sary, adjusted at the intervals specified in the peri-
odic maintenance and lubrication chart. The
carburetor is an important part of the engine and
requires very sophisticated adjustment. Therefore,
most carburetor adjustments should be left to a
Yamaha dealer, who has the necessary profes-
sional knowledge and experience. The adjustment
described in the following section, however, may
be performed by the owner as part of routine main-
tenance.
CAUTION:

ECB00480
The carburetor has been set and extensively
tested at the Yamaha factory. Changing these
settings without sufficient technical knowl-
edge may result in poor performance of or
damage to the engine.
EBU24000
Adjusting the engine idling speed
The engine idling speed must be checked and, if
necessary, adjusted as follows at the intervals
specified in the periodic maintenance and lubrica-tion chart.
NOTE:

A diagnostic tachometer is needed to make this
adjustment.
1. Start the engine and warm it up.
NOTE:

The engine is warm when it quickly responds to the
throttle.
2. Attach the tachometer to the spark plug lead.
3. Check the engine idling speed and, if neces-
sary, adjust it to specification by turning the
throttle stop screw at the carburetor. To in-
crease the engine idling speed, turn the throt-
tle stop screw in direction (a), and to decrease
it, turn the screw in direction (b).