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

  1. Place the motorcycle on the sidestand.

TIP
When checking and adjusting the drive chain slack, there should be no weight on the motorcycle.

  1. Shift the transmission into the neutral position.
  2. 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)


  1. Drive chain slack

  1. If the drive chain slack is incorrect, adjust it as follows.

To adjust the drive chain slack

  1. Loosen the axle nut and the locknut on each side of the swingarm.


  1. Axle nut

  2. Drive chain slack adjusting bolt

  3. Locknut

  4. Alignment marks

  1. 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.

  1. 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 cylinder head breather hose
    1. Remove: Left side panel Refer to "GENERAL CHASSIS" on page 4-1. 2. Check: Cylinder head breather hose "1" Cracks/damage → Replace. Loose connection → Connect properly. CAUTION:Make sure the cylinder head breather hose is routed correctly. ...

    Installing the shift forks and shift drum assembly
    1. Install: Shift fork-L "1" Shift fork-C "2" Shift fork-R "3" Shift drum assembly "4" Springs Shift fork guide bar "5" NOTE: The embossed marks on the shift forks should face towards the right side of the engine and be in the following sequence: "R", "C", "L". 2. Check: Tr ...

    Fuel tank cap
    Fuel tank cap Fuel tank cap lock cover Unlock. To remove the fuel tank cap Open the fuel tank cap lock cover. Insert the key into the lock and turn it 1/4 turn counterclockwise. The lock will be released and the fuel tank cap can be removed. To install the fuel tank ca ...

    2026 Copyright www.yam-r125.net |