| Spec | GX120 |
|---|---|
| Displacement | 122 cc |
| Bore × stroke | 60 × 43.5 mm |
| Net power | 3.2 hp (2.4 kW) @ 3,600 rpm |
| Net torque | 5.5 lb-ft (7.3 Nm) @ 2,500 rpm |
| Compression ratio | 8.3:1 |
| Oil capacity | 0.59 US qt (0.56 L) |
| Fuel tank | 2.1 US qt (2 L) |
| Dry weight | 28.9 lb (13.2 kg) |
| Ignition | Transistorized magneto |
| Starting | Recoil |
| Size (L × W × H, min) | 11.7 × 13.6 × 13.0 in (297 × 346 × 329 mm) |
Source: Honda Engines official specification pages (engines.honda.com/models/model-detail/mid-gx), checked 2 Nov 2026. Power is SAE J1349 net output measured by Honda; engines installed in equipment may vary. This site is independent and not affiliated with Honda.
Oil: how much and how to check
The GX120 holds 0.59 US quarts (0.56 L). Honda engines are filled to the edge of the oil filler neck with the engine level – don’t screw the dipstick in to check, just rest it in the neck. Overfilling is as bad as running low: excess oil can foul the plug and push out through the breather.