The power density of a two-stroke push mower is usually 20%-30% higher than that of a four-stroke model. For example, the power of the engine in an ordinary model such as Husqvarna 125B can be as high as 3.5 horsepower, but it weighs just 9.8 kilograms, 35% lighter than a four-stroke model of identical specification. Its fuel mix is 1:50 (2% engine oil ratio). 0.9 liter refilling will be enough to cover 400 to 500 square meters of lawn, and its efficiency in running is three times more than the electric model. According to data provided by the US Environmental Protection Agency (EPA), this model consumes 0.6-0.8 liters of fuel per hour to operate, and running cost amounts to approximately $0.5 per hour, saving 15% on fuel cost compared to gas four-stroke models. Tests done by the Consumer Association of Australia in 2019 showed that at running on a 30-degree slope ground, the climbing torque of the 2-stroke push mower was 18% higher than that of the four-stroke model, which is better suited for complex terrain.
Its hydrocarbon (HC) emissions, however, reach 50g/kWh, three times the four-stroke model. Based on 2021 California Air Resources Board (CARB) standards, this equipment has been banned for sale in 13 states. When it comes to maintenance intervals, the spark plugs need to be replaced every 50 hours (150 hours for four-stroke engines), and the air filter cleaning cycle is cut by 40%. A typical case was a study conducted by the Technical University of Munich in Germany in 2018, which found that following repeated 2-stroke push mower operation use for 2 hours, the ambient air around the worker had a PM2.5 level of 120μg/m³, which is 4 times the standard. Economical analysis indicates that the total expense of a five-year cycle of usage (maintenance, parts replacement and fuel) is about $480, an increase of 22% on that of the four-stroke variant, while the return on investment (ROI) decreases by 9 percentage points.
Market statistics show that the 2-Stroke push mower holds 35% of the market share in the emerging markets simply because its unit price is as low as $199 (the average four-stroke model costs $279). But the Stage V emission standard adopted by the European Union in 2023 mandates that its nitrogen oxide (NOx) emissions should be below 8g/kWh, so mainstream players like STIHL have begun phasing out production of associated products step by step. User surveys indicate that 83% of customers believe that the operation of blending oil ratios is difficult, and 23% of users have damaged the engine through improper ratios. A classic case was that out of the year-by-year complaints recorded by the Canadian Lawn Care Association in 2022, maintenance cases involving 2 stroke push mower accounted for 41% of total cases. The most common points of failure were clogging of carburetors (63% of failure types) and piston ring wear (28%).
From the perspective of noise pollution, the sound pressure level of 2-stroke push mower would generally be as high as 95-102 decibels, 12%-20% higher than outdoor machinery safety limits recommended by the WHO (85 decibels). As indicated by a Ministry of the Environment survey conducted by Japan in 2020, the noise energy of such devices in the upper frequency band (2000-4000Hz) is 27% more than that of four-stroke devices. Long-term exposure increases the risk of hearing loss in the user by 1.8 times. The United States Occupational Safety and Health Administration (OSHA) mandates operators to wear noise-cancelling ear cups when operating the 2-stroke push mower for more than 2 hours continuously, while the safety limit for the four-stroke model is 4 hours. During the real test, vibration acceleration of the Ryobi RM231 model reached 12.3m/s² at full load, 2.46 times the ergonomic limit (5m/s²), and was likely to lead to arm vibration syndrome (HAVS). These ‘hidden costs’ reduce the overall performance score of the equipment by 15-20 percentage points compared with four-stroke products.