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1.1Fault diagnostic procedure for poor engine idling
Engine does not idle
Check the cylinder
compression pressure
I n s u f f i c i e n t
compression
p r e s s u r e i n
cylinder
① Check the external joints
for any leakage
② Check the air is distributed
at correct time
③ C h e c k i f t h e v a l v e
clearance is too small
④ Check the sealing between
valve and the valve seat
⑤ Check if the piston ring is
broken or stuck in the ring
groove or lack of elasticity
⑥ Check the piston ring and
cylinder for any abrasion
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Chapter 4 Motorcycle Fault Diagnostic Procedure
Section 1 Engine Fault Diagnostic Procedure
Engine idles at too high speed
Pull the throttle and check
if it is completely closed
yes
Turn off the ignition switch,
stop for about 10 s, restart
after the idle stepper motor
returns
Normal compression
pressure in cylinder
Check the throttle body
idling bypass airway
carbon deposition in bypass airway
Clean the idle bypass airway
Still no idle speed after cleaning
Use the diagnostic tool to check
Engine idles poorly
No
Check if the throttle control cable is
pulled flexibly in the cable sleeve
and if the throttle spring is too soft
If the idle speed is
still too high, use
Check if the spark
the fault diagnostic
plug electrode
tool to check
yes
Adjust the
electrode
clearance
Engine idles unstably
Check if ignition timing
is proper or not
Use the diagnostic tool
to check
yes
No
① C h e c k i f t h e C D I
ignition is faulty
② Check the magnetic
motor flywheel and trigger
coil for any looseness
No
C h e c k t h e c o m b u s t i b l e
mixture ratio
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