Yamaha YZF-R125 Service Manual: Jumps out of gear

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 ...

Faulty clutch

Clutch slips 1. Clutch Improperly assembled clutch Improperly adjusted clutch cable Loose or fatigued clutch spring Worn friction plate Worn clutch plate 2. Engine oil Incorrect oi ...

Other materials:

Measuring the compression pressure
NOTE: Insufficient compression pressure will result in a loss of performance. 1. Measure: Valve clearance Out of specification →Adjust. Refer to "ADJUSTING THE VALVE CLEARANCE" on page 3-3. 2. Start the engine, warm it up for several minutes, and then turn it off. 3. Remove: ...

Checking the relays
Check each switch for continuity with the pocket tester. If the continuity reading is incorrect, replace the relay. 1. Disconnect the relay from the wire harness. 2. Connect the pocket tester ( × 1) and battery (12 V) to the relay terminal as shown. Check the relay operation. Out ...

Faulty lighting or signaling system
Headlight does not come on - Wrong headlight bulb - Too many electrical accessories - Hard charging - Incorrect connection - Improperly grounded circuit - Poor contacts (main or light switch) - Burnt-out headlight bulb Headlight bulb burnt out - Wrong headlight bulb - Faulty battery - Fau ...