Yamaha FT50C Service Manual page 249

Symptom: The engine idle speed is not steady, but increases or decreases.
• Check the carburetors.
• Check the air intake system.
• Check the ignition system.
Check the operation of the car-
buretor throttle valves.
Do the valves
close simul-
taneously?
No
Check the operation of the car-
buretor throttle valves by
removing the throttle cables and
link rods.
Do the valves
close simul-
taneously?
No
Check and disassemble the car-
buretors, and then clean them if
necessary.
62Y5A11
Yes
Check the ignition timing.
Out of specifi-
cation?
Yes
Replace the CDI unit.
Check the throttle cable opera-
Yes
tion and lubricate it if necessary.
Power unit
Check the second-
ary air intake on the
O-ring and manifold
No
plate, and the gas-
kets of the vacuum
check bolts.
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