Repair Procedures

Compression Pressure Test

If there is a lack of power, excessive oil consumption, or poor fuel economy, measure the compression pressure.

1. 1
   Warm up the engine to normal operating temperature (80–95 °C).
2. 2
   Remove the air duct. (Refer to Intake and Exhaust System - Air Cleaner)
3. 3
   Remove the battery. (Refer to Engine Electrical System - "Battery")
4. 4
   Remove the air cleaner assembly. (Refer to Air Intake and Exhaust System - "Air Cleaner").
5. 5
   Remove the expansion tank. (Refer to Intake and Exhaust System - "Expansion Tank")
6. 6
   Remove the ignition coils. (Refer to Engine Electrical System - "Ignition Coil")
7. 7
   Remove the spark plugs. (Refer to Engine Electrical System - "Spark Plug")
8. 8
   Check the compression pressure in the cylinder.

   1. Insert the compression gauge into the spark plug hole.
   2. Fully open the throttle valve.
   3. Crank the engine over 7 times to measure the compression pressure.

      Always use a fully charged battery to obtain an engine speed of 250 rpm or more.

   4. Repeat steps 1) through 3) for each cylinder.

      This measurement must be performed as quickly as possible.

      Compression pressure: 1373 kPa (14.0 kgf/cm², 199 psi) (250–400 rpm) Minimum pressure: 1226 kPa (12.5 kgf/cm², 178 psi) Difference between each cylinder: 98 kPa (1.0 kgf/cm², 14 psi) or less
   5. If compression in one or more cylinders is low, add a small amount of engine oil into the cylinder through the spark plug hole, then repeat steps 1) through 3) for the cylinders with low compression.

      a.	If adding oil improves compression, the piston rings and/or cylinder bore are likely worn or damaged.

      b.	If the pressure remains low, a valve may be stuck or improperly seated, or there may be a leak past the cylinder head gasket.

9. 9
   Reinstall the spark plugs.
10. 10
    Install the ignition coils and connectors.
11. 11
    Install the expansion tank. (Refer to Intake and Exhaust System - "Expansion Tank")