Ignition Timing; Cylinder Compression - KYMCO NEXXON 50 Service Manual

2
. INSPECTION/ADJUSTMENT

IGNITION TIMING

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• The CDI unit is not adjustable.
• If the ignition timing is incorrect,
check the ignition system.
Remove the ignition timing eye hole cap on
the left crankcase cover.
Check the ignition timing with a timing light.
When the engine is running at idle speed, the
ignition timing is correct if the index mark
on the left crankcase cover aligns with the
"F" mark on the flywheel.

CYLINDER COMPRESSION

Warm up the engine before compression test.
Stop the engine, then remove the spark plug
and insert a compression gauge.
Open the throttle valve fully and crank the
engine with the starter motor or kick lever.
Measure the compression.
Compression: 13±2kg/cm²
If the compression is low, check for the
following:
‧Leaky valves
‧Valve clearance to small
‧Leaking cylinder head gasket
‧Worn piston rings
‧Worn piston/cylinder
If the compression is high, it indicates that
carbon deposits have accumulated on the
combustion chamber and the piston head.
Eye Hole
Timing Light
"F" Mark
NEXXON 50
Compression Gauge
2-6