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:

    Installing the clutch
    1. Install: Conical spring washer "1" NOTE: Install the conical spring washer as shown in the illustration. 2. Install: Clutch housing Thrust washer "1" NOTE: Be sure to install the thrust washer so that its sharp edge "a" is facing away from the clutch boss. 3. Instal ...

    Assembling the front wheel
    1. Install: Wheel bearings Oil seal a. Install the new wheel bearings and oil seal in the reverse order of disassembly. CAUTION:Do not contact the wheel bearing inner race "1" or balls "2". Contact should be made only with the outer race "3". NOTE: Use a socket " ...

    Installing the rear brake master cylinder
    1. Install: Copper washers "1" Brake hose "2" Rear brake light switch "3" WARNINGProper brake hose routing is essential to insure safe vehicle operation. Refer to "CABLE ROUTING" on page 2-33. CAUTION:When installing the brake hose onto the brake master ...

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