49cc DirtBike for Sale. Powerful 3.4HP ASUN two-stroke air-cooled motor (with kick-start) that's matched up to a 4 speed semi-automatic transmission with 2.50 x 10 off-road tires. Suspension is provided by telescoptic forks out front and an adjustable mono-shock in the rear. Maximum load is 150kg, and max speed is rated at 65km/h. Used, but in good condition.