Yamaha YZF-R125 Service Manual: Poor medium-and-high-speed performance

Yamaha YZF-R125 Service Manual / Troubleshooting / Poor medium-and-high-speed performance

Refer to "STARTING FAILURES" on page 9-1.

Engine

1. Air filter

  • Clogged air filter element

Fuel system

1. Fuel pump

  • Faulty fuel pump

Faulty gear shifting

Shifting is difficult

Refer to "Clutch drags".

    Incorrect engine idling speed
    Engine 1. Cylinder and cylinder head Incorrect valve clearance Damaged valve train components 2. Air filter Clogged air filter element Fuel system 1. Throttle body Damaged or loo ...

    Shift pedal does not move
    Shift shaft Improperly adjusted shift rod Bent shift shaft Shift drum and shift forks Foreign object in a shift drum groove Seized shift fork Bent shift fork guide bar Transmission ...

    Other materials:

    Checking the front brake lever free play
    Checking the front brake lever free play Brake lever free play The brake lever free play should measure 2.0-5.0 mm (0.08-0.20 in) as shown. Periodically check the brake lever free play and, if necessary, have a Yamaha dealer check the brake system. WARNING An incorrect brake le ...

    Checking the relays
    Check each switch for continuity with the pocket tester. If the continuity reading is incorrect, replace the relay. 1. Disconnect the relay from the wire harness. 2. Connect the pocket tester ( × 1) and battery (12 V) to the relay terminal as shown. Check the relay operation. Out ...

    Adjusting the clutch cable free play
    1. Check: Clutch cable free play "a" Out of specification Adjust. 2. Adjust: Clutch cable free play a. Pull back the rubber cover "1" b. Loosen the locknut "2". c. Turn the adjusting bolt "3" in direction "a" or "b" until the specified clutch cable free play is obtained. ...

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