Lawnmower engines are usually somewhere within the region of 3.5 - 5hp, which is fairly powerful. However these engines are slow, producing between 3500rpm and 4500rpm, the later figure where the engine is over-clocked. The good side to this however is that they produce plenty of torque to get a kart in motion. Been readily available makes them sometimes the last resort in kart engines. They require a lot of adoption and messing around with the drive to adapt them so they can drive a horizontal axle (the wheels). "If only we could just put the engine on it's side". If only!. However this is not the best of ideas as you risk top end failure - piston seizure etc.
The problem is the fact that the drive axle (power shaft/ crankshaft comes out from the underneath of the engine. Producing vertical drive, however our rear axle turns in a horizontal axis. And it is this problem of getting the power of the engine to the rear wheels. Anyways we will come to all that later here.
Meanwhile here is a typical picture of an average lawnmower engine we will be later adapting to fit a kart.
