KYMCO Mongoose 90

3. INSPECTION/ADJUSTMENT
3-7
Gap, Wear, and Fouling Deposits
SPARK PLUG
Remove the ignition coil cap and spark
plug.
Check the spark plug for wear and fouling
deposits.
Clean any fouling deposits with a spark
plug cleaner or a wire brush.
Specified Spark Plug:
90cc/70cc/50cc-4T: NGK: CR7HSA
50cc-2T: NGK: BR8HAS
Measure the spark plug gap.
Spark Plug Gap:
0.6～0.7 mm (0.024～0.028 in)
CYLINDER COMPRESSION
Warm up the engine before compression
test.
Remove the spark plug.
Insert a compression gauge.
Open the throttle valve fully and push the
starter button to test the compression.
Compression:
90 cc: 16 kgf/cm²(1600 kPa, 227.2 psi)
70 cc: 14 kgf/cm²(1400kPa, 198.8 psi)
50 cc-4T: 14 kgf/cm²(1400kPa, 198.8 psi)
50 cc-2T: 12 kgf/cm²(1200kPa, 170.4 psi)
If the compression is low, check for the
following:
- Leaky valves
- Valve clearance too 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.
Cracks, Damage
Washer Deformation
Ignition Coil Cap/Spark Plug
When installing, first screw in the spar
k
plug by hand and then tighten it with a
spark plug wrench.
＊
Compression Gauge