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:

Checking the valves and valve guides
The following procedure applies to all of the valves and valve guides. 1. Measure: Valve-stem-to-valve-guide clearance Out of specification Replace the valve guide. Valve-stem-to-valve-guide clearance = Valve guide inside diameter "a" - Valve stem diameter "b" 2. Replace: ...

Tires
To maximize the performance, durability, and safe operation of your motorcycle, note the following points regarding the specified tires. Tire air pressure The tire air pressure should be checked and, if necessary, adjusted before each ride. WARNING Operation of this vehicle with impro ...

Self-diagnostic function table
If the ECU detects an abnormal signal from a sensor while the vehicle is being driven, the ECU illuminates the engine trouble warning light and provides the engine with alternate operating instructions that are appropriate for the type of malfunction. When an abnormal signal is received fro ...