Adjustment; Cylinder Compression - KYMCO AHG5 Service Manual

3. PERIODIC MAINTENANCE

7.2. Adjustment

Place a 9 mm box end wrench over the
locknut, and loosen the locknut. If the valve
clearance is tight back out the valve tappet
adjusting screw with the tappet adjustment
tool. If the clearance is too loose turn in the
adjusting screw until there is a light drag on
the feeler gauge. Hold the adjusting screw
locknut in place with the wrench to make
sure it doesn't interfere with the adjustment.
Lubricate the tappet adjusting screw threads
with fresh engine oil. Hold the adjuster in
place and tighten the locknut. Always
recheck the clearance after tightening the
locknut. Also, recheck after turning the
engine over and back to TDC on the
compression stroke.
Install the removed parts in the reverse
order of removal.
Make sure the O-rings on the crankshaft and
timing plugs are in good condition.
Replace them as needed. Install the timing
inspection and crankshaft caps to the right
side of the engine. Tighten the caps securely
but not overly with a large flat blade
screwdriver.

8. Cylinder Compression

Warm up the engine before compression
test.
Remove the center cover and spark plug
cap. Remove the spark plug.
Insert a compression gauge.
Open the throttle valve fully and push the
starter button to test the compression.
Compression: 12±2 kgf/cm
Torque: 0.7~1.1 kgf-m
Special tool:
Valve adjuster
If the compression is low, check for the
following:
If the compression is high, it indicates that
2
carbon deposits have accumulated on the
combustion chamber and the piston head.
3-10
DT X360
A120E00012

Leaky valves

Valve clearance to small

Leaking cylinder head gasket
 Worn pistons
 Worn piston/cylinder