SPECIFICATIONS
GX390
*1: The power rating of the engine indicated in this document is the net power output tested on a production engine for the
engine model and measured in accordance with SAE J1349 at 3,600 rpm (net power) and at 2,500 rpm (max net torque).
Mass production engines may vary from this value. Actual power output for the engine installed in the final machine will
vary depending on numerous factors, including the operating speed of the engine in application, environmental conditions,
maintenance, and other variables.
Model GX390R2 GX390RT2 GX390U2 GX390UT2 GX390T2
Description code GCBHK GCBCT GCBHK GCBCT GCBDT
Type 4 stroke, overhead valve, single cylinder, inclined by 25°
Displacement 389 cm3 (23.7 cu–in)
Bore x stroke 88.0 x 64.0 mm (3.5 x 2.5 in)
Net power (SAE J1349)*1 8.7 kW (11.7 HP) / 3,600 min-1 (rpm)
Continuous rated power 7.0 kW (9.4 HP) / 3,600 min-1 (rpm)
Maximum net torque (SAE J1349)*1 26.5 N·m (2.7 kgf·m, 19.5 lbf·ft) / 2,500 min-1 (rpm)
Compression ratio 8.2 ± 0.2: 1
Fuel consumption
(at continuous rated power)
3.5 Liters (0.92 US gal, 0.77 Imp gal) / h
Ignition system C.D.I.(Capacitor Discharge Ignition) type magneto ignition
Ignition timing B.T.D.C. 10° / 1,400 min-1 (rpm)
Spark plug BPR6ES (NGK) / W20EPR-U (DENSO)
Lubrication system Forced splash
Oil capacity 1.1 Liters (1.16 US qt, 0.97 Imp qt)
Recommended oil SAE 10W-30 API service classification SJ or later
Cooling system Forced air
Starting system Recoil, Recoil and Starter motor
Stopping system Ignition primary circuit open
Carburetor Horizontal type, butterfly valve
Air cleaner Dual element type, Cyclone type, Low profile type
Governor Mechanical centrifugal
Breather system Reed valve type
Fuel used Unleaded gasoline with a pump octane rating 86 or higher