It definately can be done,like grumpy said-change the flywheel to a ring-gear type,fit the starter motor-starter switch or just a push button type,install the battery (motor bike size will do)and connect it all up.the wiring is simple and can be sorced from here.you only need the battery to activate the starter motor because the coil(s)will provide their own power for spark.every now and then just charge the battery up with a car charger.one of my ride ons is like this and it gets charged about every two months over night because my inbuilt regulater/rectifier (electronic)is blown...ken
