Poor Medium-And-High-Speed Performance; Faulty Gear Shifting; Faulty Clutch - Yamaha YBR250 2007 Service Manual

PERFORMANCE/FAULTY GEAR SHIFTING
POOR MEDIUM-AND-HIGH-
SPEED PERFORMANCE
Refer to "STARTING FAILURES".
ENGINE
Air filter
• Clogged air filter element

FAULTY GEAR SHIFTING

SHIFTING IS DIFFICULT
Refer to "CLUTH DRAGS"
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
• Seized transmission gear
• Foreign object between transmission gears
• Improperly assembled transmission

FAULTY CLUTCH

CLUTCH SLIPS
Clutch
• Improperly assembled clutch
• Improperly adjusted clutch cable
• Loose or fatigued clutch spring
• Worn friction plate
• Worn clutch plate
Engine oil
• Incorrect oil level
• Incorrect oil viscosity (low)
• Deteriorated oil
POOR MEDIUM-AND-HIGH-SPEED
FAULTY CLUTCH
FUEL SYSTEM
Fuel pump
• Faulty fuel pump
JUMPS OUT OF GEAR
Shift shaft
• Incorrect shift pedal position
• Improperly returned stopper lever
Shift forks
• Worn shift fork
Shift drum
• Incorrect axial play
• Worn shift drum groove
Transmission
• Worn gear dog
CLUTCH DRAGS
Clutch
• Unevenly tensioned clutch springs
• Warped pressure plate
• Bent clutch plate
• Swollen friction plate
• Bent clutch push rod
• Damaged clutch boss
• Burnt driven gear bushing
Engine oil
• Incorrect oil level
• Incorrect oil viscosity (high)
• Deteriorated oil
8-3
TRBL
?
SHTG