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:

Checking the coolant level
1. Stand the vehicle on a level surface. NOTE: Place the vehicle on a suitable stand. Make sure the vehicle is upright. 2. Check: Coolant level The coolant level should be between the maximum level mark "a" and minimum level mark "b". Below the minimum level mark →  Add t ...

Adjusting the rear disc brake
1. Check: Brake pedal position (distance "a" from the center of the rider footrest to the center of the brake pedal) Out of specification Adjust. 2. Adjust: Brake pedal position a. Loosen the locknut "1". b. Remove the cotter pin "2", washer "3", and pin "4". c. Turn t ...

Installing the cylinder head
1. Install: Cylinder head NOTE: Pass the timing chain through the timing chain cavity. 2. Tighten: Cylinder head bolts "1" Cylinder head bolts "2" NOTE: Lubricate the cylinder head bolts and washers with engine oil. Tighten the cylinder head bolts in the proper tighten ...