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:

Avoid Carbon Monoxide Poisoning
All engine exhaust contains carbon monoxide, a deadly gas. Breathing carbon monoxide can cause headaches, dizziness, drowsiness, nausea, confusion, and eventually death. Carbon Monoxide is a colorless, odorless, tasteless gas which may be present even if you do not see or smell any en ...

Battery
A poorly maintained battery will corrode and discharge quickly. The electrolyte level, battery lead connections and breather hose routing should be checked before each ride and at the intervals specified in the periodic maintenance and lubrication chart. WARNING Electrolyte is pois ...

Checking the brake fluid level
Front brake Front brake Minimum level mark Rear brake Rear brake Minimum level mark Insufficient brake fluid may allow air to enter the brake system, possibly causing it to become ineffective. Before riding, check that the brake fluid is above the minimum level mark an ...