[bradfa]

2-strokes output more power. This isn't my proposal, this is a thing which exists in the world today, produced by various different engine manufacturers for sale to the public today in motorcycles.

Miniaturizing it to work on a hand-held lawn care device is just an engineering task.

[snovv_crash]

It needs a high pressure rail with fuel pump, electronic injection and ignition control. This adds considerably to the cost, which when you take it into the engineering optimization problem, starts pointing to electric plus batteries for these small sizes. You need about 100cc before it makes sense to start looking for fuel engines, or some application that requires really high energy density for long endurance at light weight (eg. surveillance drones).