Check engine compression at normal operating temperature at specified cranking speed. Release fuel pressure. See FUEL SYSTEM . Remove left air duct and disconnect power transistor connectors. Remove left harness connector bracket and ornamental rocker covers. Disconnect harness connector between ignition coil and power transistor. Remove ignition coil bracket and bracket with ignition coils. Remove all spark plugs. Depress accelerator pedal fully to hold throttle valve wide open. See COMPRESSION SPECIFICATIONS table.

NOTE: If cylinder compression in one or more cylinders is low, repeat inspection using a small amount of oil poured into each cylinder. If compression pressure increases, piston rings may be worn or damaged. If compression pressure does not increase, a valve may be sticking or seating improperly. If compression in any 2 adjacent cylinders is low and does not change after oil is added, there is a leak past head gasket. Make repairs as needed and reinspect.

COMPRESSION SPECIFICATIONS ⁽¹⁾

Application

psi (kg/cm² )

Standard

185 (13.0)

Minimum

142 (10.0)

Maximum Variation Between Cylinders

14 (1.0)

⁽¹⁾	Readings taken at cranking speed (300 RPM).

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Engine Compression: Compression

Use the Manual With the Right Hardware

When to See a Mechanic

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