Yamaha YZF-R125 Owners Manual: Drive chain slack
The drive chain slack should be checked before each ride and adjusted if necessary.
To check the drive chain slack
- Place the motorcycle on the sidestand.
TIP
When checking and adjusting the drive
chain slack, there should be no weight
on the motorcycle.
- Shift the transmission into the neutral position.
- Move the rear wheel by pushing the motorcycle to locate the tightest portion of the drive chain, and then measure the drive chain slack as shown.
| Drive chain slack: 30.0-40.0 mm (1.18-1.57 in) |
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Drive chain slack
- If the drive chain slack is incorrect, adjust it as follows.
To adjust the drive chain slack
- Loosen the axle nut and the locknut on each side of the swingarm.
-
Axle nut
-
Drive chain slack adjusting bolt
-
Locknut
-
Alignment marks
- To tighten the drive chain, turn the drive chain slack adjusting bolt on each side of the swingarm in direction (a). To loosen the drive chain, turn the adjusting bolt on each side of the swingarm in direction (b), and then push the rear wheel forward. NOTICE: Improper drive chain slack will overload the engine as well as other vital parts of the motorcycle and can lead to chain slippage or breakage. To prevent this from occurring, keep the drive chain slack within the specified limits.
TIP
Using the alignment marks on each
side of the swingarm, make sure that
both drive chain pullers are in the same
position for proper wheel alignment.
- Tighten the axle nut, then the locknuts to their specified torques.
| Tightening torques: Axle nut: 85 Nm (8.5 m.kgf, 61 ft.lbf) Locknut: 16 Nm (1.6 m.kgf, 11 ft.lbf) |
Changing the brake fluid
Have a Yamaha dealer change the
brake fluid at the intervals specified in
the periodic maintenance and lubrication
chart. In addition, have the brake
hose replaced every four years or
whenev ...
Cleaning and lubricating the drive chain
The drive chain must be cleaned and
lubricated at the intervals specified in
the periodic maintenance and lubrication
chart, otherwise it will quickly wear
out, especially when riding in dusty ...
Other materials:
Checking the speed sensor
1. Check:
Speed sensor output voltage
Out of specification → Replace.
a. Connect the pocket tester (DC 20 V) to the
speed sensor coupler (wire harness end) as
shown.
Positive tester probe
gray "1"
Negative tester probe
gray/black "2"
b. Set the main switch to "ON".
c. ...
Sidestand
The sidestand is located on the left side
of the frame. Raise the sidestand or
lower it with your foot while holding the
vehicle upright.
TIP
The built-in sidestand switch is part of
the ignition circuit cut-off system, which
cuts the ignition in certain situations.
WARNING
The vehicl ...
Checking the primary drive gear
1. Remove:
Primary drive gear
Refer to "BALANCER GEAR" on page 5-53.
2. Check:
Primary drive gear
Damage/wear Replace the
primary drive
gear and clutch housing as a set.
Excessive noise during operation
Replace
the primary drive gear and clutch housing as
a set
...