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:

    Troubleshooting details
    This section describes the measures per fault code number displayed on the FI diagnostic tool. Check and service the items or components that are the probable cause of the malfunction following the order given. After the check and service of the malfunctioning part have been completed, re ...

    Checking the shift shaft
    1. Check: Shift shaft Bends/damage/wear Replace. Shift shaft spring Damage/wear Replace. Checking the stopper lever 1. Check: Stopper lever Bends/damage Replace. Roller turns roughly Replace the stopper lever. Stopper lever spring Damage/wear Replace. ...

    Preparation for removal and disassembly
    1. Before removal and disassembly, remove all dirt, mud, dust and foreign material. 2. Use only the proper tools and cleaning equipment. Refer to "SPECIAL TOOLS" on page 1-8. 3. When disassembling, always keep mated parts together. This includes gears, cylinders, pistons and other part ...

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