lock YAMAHA YFM90R 2021 User Guide

9-20
9
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).
TIPIf the specified idling speed cannot be obtained as
described above, have a Yamaha dealer make the
adjustment. EBU38470Adjusting the throttle lever free play
1. Throttle stop screwEngine idling speed:1600–1800 r/min
(a)
(b)
1
1. Rubber cover
2. Throttle lever free play adjusting nut
3. Locknut
4. Throttle lever free playThrottle lever free playW1.5

9-21
9Periodically check the throttle lever free play and
adjust if necessary.
TIPThe engine idling speed must be checked and ad-
justed before adjusting the throttle lever free play. 1. Slide the rubber cover away from the locknut.
2. Loosen the locknut.
3. To increase the throttle lever free play, turn
the throttle lever free play adjusting nut in di-
rection (a). To decrease the throttle lever free
play, turn the adjusting nut in direction (b).
4. Tighten the locknut.
5. Slide the rubber cover to its original position.EBU24062Valve clearanceThe valve clearance changes with use, resulting in
improper air-fuel mixture and/or engine noise. To
prevent this from occurring, the valve clearance
must be adjusted by a Yamaha dealer at the inter-
vals specified in the periodic maintenance chart.
EBU29602BrakesReplacement of brake components requires pro-
fessional knowledge. Brake service should be
performed by a Yamaha dealer.
WARNING
EWB02572Operating with improperly serviced or adjust-
ed brakes could lead to a loss in braking ability
and an accident. EBU34512Checking the front and rear brake
shoesThe front and rear brake shoes must be checked
for wear at the intervals specified in the periodic
maintenance chart. Without disassembling the
brake, this can be performed by checking the po-
sition of the brake lever free play adjusting bolts or
nut.
Front brakes
To check front brake shoe wear, check the posi-
tion of the adjusting bolts. If a bolt extends more
than 12 mm (0.47 in) from its locknut, the brake
shoes need to be replaced.
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9-23
9
EBU24334Adjusting the front brake lever free
playPeriodically check the front brake lever free play
and adjust if necessary.1. Loosen the upper locknut and fully turn in the upper adjusting bolt.
2. Loosen the lower locknut.
3. Turn the lower adjusting bolt in direction (a) to increase the lever free play, and in direction
(b) to decrease it. 4. Tighten the lower locknut.
5. While applying the front brake, turn out the
upper adjusting bolt until the upper and lower
cable lengths are equal. The cable joint will
become vertical.1. Front brake lever free playFront brake lever free play:20.0–25.0 mm (0.79–0.98 in)
1
1. Upper locknut
2. Upper adjusting bolt
3. Lower locknut
4. Lower adjusting bolt
1 2
4
3 (a)
(b)
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9-24
9
6. Tighten the upper locknut.
TIPAfter adjusting the brake lever free play, check the
front brake shoes for wear.
EBU33784Adjusting the rear brake lever free playPeriodically check the rear brake lever free play
and adjust if necessary.
Turn the adjusting nut in direction (a) to increase
the brake lever free play, and in direction (b) to de-
crease it.
1. Cable joint1
aa´
a=a´
1. Rear brake lever free playRear brake lever free playW
30.0

9-26
9
2. Loosen the rear brake lever free play adjust- ing nut. 3. Loosen the locknut.
1. Bolt
1. Nut
1
1
1. Rear brake lever free play adjusting nut
1. Drive chain slack adjusting nut
2. Locknut
1
1
2
(a)
(b)
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9-27
94. To tighten the drive chain, turn the drive chain
slack adjusting nut in direction (a). To loosen
the drive chain, turn the adjusting nut in direc-
tion (b) and push the rear wheels forward.
NOTICE: Improper drive chain slack will
overload the engine as well as other vital
parts of the ATV and can lead to drive
chain slippage or breakage. To prevent
this from occurring, keep the drive chain
slack within the specified limits.
[ECB00543]
5. Tighten the locknut, and then the bolts and nuts to their specified torques.
6. Adjust the rear brake lever free play. (See page 9-24.)
EBU24885Lubricating the drive chainThe drive chain must be cleaned and lubricated at
the intervals specified in the periodic maintenance
chart, otherwise it will quickly wear out, especially
when riding in dusty or wet areas. Service the
drive chain as follows.NOTICEECB00562The drive chain must be lubricated after wash-
ing the ATV or riding in the rain or wet areas.
Tightening torques:Locknut:22 N·m (2.2 kgf·m, 16 lb·ft)
Bolt: 45 N·m (4.5 kgf·m, 33 lb·ft)
Nut: 54 N·m (5.4 kgf·m, 40 lb·ft)
1. O-ring
1
1
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10-1
10
EBU25861
CLEANING AND STORAGE
EBU25903CleaningFrequent, thorough cleaning of your ATV will not
only enhance its appearance but will improve its
general performance and extend the useful life of
many components.1. Before cleaning the ATV: a. Block off the end of the exhaust pipe toprevent 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, apply degreaser with a paint brush. Do not apply
degreaser to the chain, sprockets or wheel
axles.
3. Rinse the dirt and degreaser off with a garden hose. Use only enough pressure to do the
job. WARNING! Wet brakes may have re-
duced stopping ability, increasing the
chance of an accident. Test the brakes af-
ter washing. Apply the brakes several
times at slow speeds to let friction dry out
the linings.
[EWB02312]
NOTICE: Excessive wa- ter pressure may cause water seepage
and deterioration of wheel bearings,
brakes, transmission seals and electrical
devices. Many expensive repair bills have
resulted from improper high-pressure de-
tergent applications such as those avail-
able in coin-operated car washers.
[ECB00712]
4. Once most of the dirt has been hosed off,
wash all surfaces with warm water and mild,
detergent-type soap. An old toothbrush or
bottle brush is handy for hard-to-reach pla-
ces.
5. Rinse the ATV off immediately with clean wa- ter and dry all surfaces with a chamois, clean
towel or soft absorbing cloth.
6. Dry the chain and lubricate it to prevent it from rusting.
7. Clean the seat with a vinyl upholstery cleaner to keep the cover pliable and glossy.
8. Automotive type wax may be applied to all painted and chrome plated surfaces. Avoid
combination cleaner-waxes. Many contain
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10
e. Install the spark plug and the spark plug
cap.
6. Lubricate all control cables and the pivoting points of all levers.
7. Put the frame on stands or blocks to raise all wheels off the ground. (Alternatively, turn the
wheels each month to prevent the tires from
degrading in one spot.)
8. Cover the muffler outlet with a plastic bag to prevent moisture from entering it.
9. Remove the battery and fully charge it. (See page 9-31.)
UBD365E0.book Page 3 Monday, January 27, 2020 9:05 AM