Yamaha XC125 User Manual

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SPARK PLUG INSPECTION ADJ
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When cranking the engine, ground the spark
plug lead to prevent sparking.
• If pressure falls below the minimum level:
1)Squirt a few drops of oil into the cylin-
der.
2)Measure the compression again.
Compression Pressure
(with oil introduced into cylinder)
Reading Diagnosis
Higher than Worn or damaged __
without oil piston rings.
Defective ring(s), valves,
Same as without
oil cylinder head gasket or
piston is possible.
Above maximum Inspect cylinder head,
valve surfaces, or piston
level
crown for carbon deposits.
SPARK PLUG INSPECTION
1. Inspect:,
• Electrode (_)
Wear/Damage -_ Replace.
® Insulator color _)
(_ Normal condition is a medium to light
tan color.
_) Distinctly different color -* Check the
engine condition.
_ Sparkplug gap
2. Clean:
® Spark plug
Clean the spark plug with a spark plug
cleaner or wire brush.
3. Inspect:
o Spark plug type
Incorrect -+ Replace.
2-12
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Yamaha XC125 Specifications

General

Displacement	125cc
Bore x Stroke	52.4 mm x 57.9 mm
Fuel System	Fuel Injection
Front Suspension	Telescopic fork
Rear Suspension	Unit Swing
Seat Height	780 mm
Engine Type	4-stroke, SOHC, 2-valve
Starter System	Electric
Transmission	V-Belt Automatic
Front Brake	Single disc
Rear Brake	Drum
Engine	Single cylinder, 4-stroke, air-cooled, SOHC