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

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:

Coolant
The coolant level should be checked before each ride. In addition, the coolant must be changed at the intervals specified in the periodic maintenance and lubrication chart. To check the coolant level Place the vehicle on a level surface and hold it in an upright position. TIP ...

Disassembling the front wheel
1. Remove: Oil seal Wheel bearings a. Clean the surface of the front wheel hub. b. Remove the oil seal "1" with a flat-head screwdriver. NOTE: To prevent damaging the wheel, place a rag "2" between the screwdriver and the wheel surface. c. Remove the wheel bearings "3" with a ge ...

Main switch/steering lock
Main switch/steering lock The main switch/steering lock controls the ignition and lighting systems, and is used to lock the steering. The various positions are described below. ON All electrical circuits are supplied with power, the meter lighting, taillight, license plate light and ...