Poor Performance At Idle Speed; Unsatisfactory Performance At Medium-High Speed; Difficulties In Changing Gear; Gear Change Impossible - Yamaha SZR 660 Service Manual

POOR PERFORMANCE
AT
IDLE
SPEED/
UNSATISFACTORY PERFORMANCE AT MEDIUM-HIGH SPEED
DIFFICULTIES
IN
CHANGING GEAR
TRBL
SHTG
9
POOR PERFORMANCE
AT
IDLE
SPEED
—
Carburetor
PROBABLE CAUSES
•
The
starter piston fails to return freely
•
Pilot
jet
obstructed
or toose
•
Pilot air
jet
obstructed
•
Pilot air
screw wrongly
set
•
Idle
speed
wrongly
set
(throttle
vatve
locking
screw)
•
Throttle
cable free
play wrongly
set
•
Carburettor flooded
DIFFICULTIES
IN
CHANGING GEAR
GEAR CHANGE
IMPOSSIBLE
-
Clutch
Electrical
system.
Valves
Defective battery
Defective spark plug
Defective
ignition unit
Pick-up
coil defective
Defective
ignition coil
Valve
free play
wrongly
set
Engine
oil
UNSATISFACTORY
PERFORMANCE
AT MEDIUM-HIGH SPEED
See "FAILURE
TO
START/DIFFICULTIES
IN
STARTING".
(FUEL
SYSTEM, ELECTRICAL SYSTEM, COMPRESSION SYSTEM
and
Valve
Clearance}
THE GEAR PEDAL
FAILS
TO
MOVE
—
Gear
shaft
Carburetor
PROBABLE CAUSES
•
Petrol
contains water or impurities or
is
adulterated
•
Infiltrations of air
• Deformation
of fioat
Defective
diaphragm
Needle
valve
worn
or
scratched
Needle valve housing
insufficiently
sealed
Needle stop
position incorrect
Needle
clip
position incorrect
Fuel level set
wrongly
Main
jet
obstructed or loose
Main nozzle obstructed
or foose
Gear cam,
gear fork
Transmission
DISENGAGING
GEARS
—
Gear shaft
—
Air filter
Air fitter
element obstructed
Fuel
pump
Fuel
pump
defective
Gear
fork
Gear
cam
PROBABLE CAUSES
•
Clutch cable wrongly
set (clutch fails release)
•
Wrong
position of driving tever
•
irregular
engagement
of
push
iever
and push
rod
• Pressure
plate
deformed
•
Clutch springs not
preloaded uniformly
• Reference
marks
not
aligned
• Push
rod broken
• Clutch gear assy nut loose
or thrust
rod de-
formed
• Primary driven
gear bearing defective
• Driven
plates
deformed
•
Driving plates deformed
• Clutch cable
damaged
• Oil level
over
maximum
•
Excessive
viscosity
of engine
oil
• Degradation
PROBABLE CAUSES
•
Gear
shaft
deformed
Groove
with impurities or foreign
bodies
Gear
fork stuck
Fork guide bar deformed
Transmission gears stuck
Gears
stuck by impurities or foreign
bodies
Wrong
transmission
assembly
PROBABLE CAUSES
•
Gear tever set wrongly
•
Drum
stop
lever fails
to return freely
• Gear
forks
worn
Transmission
Shaft
cam
with thrust
free
play
Gear cam
groove worn
Gear
clutches
worn
9-3 9-4