The dynamic performance of two-stroke push mower is good in cutting thick grass: Typical models such as Husqvarna 125L are equipped with a 25cc engine, with power of 1.2kW (approximately 1.6 horsepower), maximum torque of 0.8N·m, blade speed of 9000rpm (linear speed of 20m/s), and cut grass stems with diameter of ≤5mm (grass height ≤25cm). United States Department of Agriculture tests show that when it cuts high-density Bermuda grass (320 plants per square meter), its cutting efficiency stands at 85% (90% for four-stroke models), but after continuous operation for 30 minutes, the power attenuation is 12% (5% for four-stroke models). With a fuel ratio of 50:1 (gasoline: engine oil), the fuel consumption is 0.8 liters per hour, and the operating cost is approximately 0.6 US dollars per hour (electricity is taken at 0.1 US dollars per kWh, and the price of an electric lawn mower is 0.2 US dollars per hour).
The load capacity and the thickness of the blade directly determine the thick grass treatment effect: There are two stroke models with primarily double-edged steel blades (2.5mm thick, 25°edge Angle), with a grass chip throw distance of 1.8m and a cutting width of 38cm. In a Kentucky bluegrass lawn with a grass height of 20cm and a moisture content of 70%, the single-pass cutting completion rate is just 65%, and the operation must be repeated 2-3 times (1-2 times for four-stroke models), lowering the efficiency by 40%. Yet, with the conversion of high-torque blades (such as Oregon 90-347), the torque can be increased by 15% (up to 0.92N·m), and the processing capacity for grass chips can be increased from 15L/hour to 20L/hour. It is suitable for courtyards with a size of ≤800㎡.
Environmentally, the two-stroke model runs smoothly in terrain with a slope of ≤30°. However, engine load rate is more than 85% with the grass layer density of ≥400 plants per square meter, increasing cylinder temperature to 180℃ (four-stroke engine, below 160℃), and increasing the carbon deposit rate of the spark plug by 300% (every 10 hours cleaning required). Statistics by the US Environmental Protection Agency (EPA) reveal that its HC+NOx emissions are equivalent to 28g/kWh (0g for electric mowers), and it is regulated by use restrictions in stringently emission regions such as California.
Real-world applications verify the performance limit: A Florida operator treated 25cm tall St. Augustine grass (stem diameter of 4mm) with 2 stroke push mower. The efficiency of operation dropped to 50㎡/ hour (120㎡/ hour when the normal grass height was 10cm), and the engine had to be shut down every 15 minutes to cool to avoid cylinder pulling. In the comparative test, under the same working conditions, the working capacity of the EGO Power+ 56V electric lawn mower (torque 1.1N·m) was 80㎡/ hour, but the cost was three times higher (300 US dollars vs 100 US dollars).
Maintenance costs and longevity costs should be traded off: On two-stroke versions, air filter needs to be replaced at 25 hours ($3) and spark plugs at 50 hours ($5). Annual maintenance cost is around $45 (a mere $20 on electric models). But its mechanical construction is simple, and the time to rectify malfunctions is 40% shorter than the four-stroke engine (average repair time is 0.5 hours as opposed to 0.8 hours). In developing world markets (e.g., India), with the widespread availability and low cost of fuel (gasoline at $0.9 /L), two-stroke models continue to hold 75% of market share, and are best for handling dense weeds (e.g., elephant grass) in the tropics.
Groundbreaking technology enhances potential: Mitsubishi launched the TLE43 engine in 2023, which increased the power for thick grass usage to 1.4kW (+16%) through layer-by-layer scavenging technology, improved fuel efficiency by 12% (0.7L/hour), and reduced emissions to 18g/kWh. The factory advises that in case of extremely thick grass, the “segmented cutting” method (cutting initially to 15cm and later fine-cutting to 8cm) may be applied in order to increase the overall effectiveness of the 2-stroke push mower by 35%.