KOSS Petrol Grass Trimmer with Line DEMON RQ580 – 51.7 cm³ 2-Stroke, 5.2 HP, Dual Line Bump Feed, Bike Handle

The DEMON RQ580 petrol grass trimmer from KOSS stands out in the 2-stroke class by pairing a high-displacement 51.7 cm³ engine with a robust solid steel drive shaft and a dual-line bump feed head. Unlike smaller 25–30 cm³ trimmers that bog down in thick weeds, this unit delivers 3.8 kW (5.2 HP) at up to 8000 RPM, letting you power through overgrown grass, brambles, and light brush without constant throttle management. The fixed shaft and 8 mm inner drive core transfer power with minimal vibration, while the included multi-tooth metal blade expands capability beyond line trimming to woody stems and dense undergrowth.

Highlights

• Powerful 51.7 cm³ air-cooled 2-stroke engine – 3.8 kW / 5.2 HP for demanding cutting tasks
• Dual cutting system: 420 mm line width with bump feed head, plus 255 mm metal blade for brush
• Ergonomic bike handle (U-handle) with double shoulder harness for all-day balance and control
• Solid steel drive shaft (8 mm inner / 26 mm outer tube) – no flex cable, no power loss
• Electronic CDI ignition and manual recoil start for reliable cold starts
• Large 1.2 L fuel tank with 25:1 petrol-oil mix ratio for extended run time

In daily use

Starting the RQ580 is straightforward: prime the carburettor, set the choke, and pull the recoil handle – the CDI ignition fires quickly even after storage. The bike handle spreads your grip wide, reducing wrist strain on slopes and around fences, while the double shoulder harness transfers weight to your hips. The bump feed head releases line with a light tap on the ground, and the 2.4–3.0 mm line compatibility lets you choose thicker line for tougher weeds. When switching to the metal blade, the 255 mm cutting width slices through saplings and thick stalks, but always use the included guard and wear appropriate PPE. The fixed shaft means no flex-cable lag, so the head responds instantly to throttle input.

Full specifications

• Engine type: 2-stroke, air-cooled
• Displacement: 51.7 cm³
• Max power: 3.8 kW / 5.2 HP
• Max engine speed: 8000 RPM
• Idle speed: 3000 RPM
• Fuel tank capacity: 1.2 L
• Fuel mix ratio: 25:1 (petrol:oil)
• Starting system: manual recoil
• Ignition: electronic CDI
• Cutting width (line): 420 mm
• Cutting width (blade): 255 mm
• Cutting head: dual line bump feed, multi-tooth metal blades included
• Line diameter compatibility: 2.4–3.0 mm
• Shaft: fixed, solid steel drive shaft (8 mm inner / 26 mm outer tube)
• Handle: ergonomic bike handle (U-handle)
• Harness: double shoulder harness
• Noise level (LwA): 113 dB(A)

Final note

The KOSS DEMON RQ580 is a serious tool for landowners, farmers, and professional gardeners who need petrol power and dual cutting capability without the weight of a brushcutter. Its high-displacement engine and rigid shaft make it a step above typical homeowner trimmers, while the included harness and bike handle keep it manageable for long sessions.