you could try extending the front frame and moving the front suspension forwards to add an i6 from an etk or the hopper
yeah thats cool, I just really like the idea of extending the whole front to fit a huge engine, might do it myself at some point
how about something unconventional, like a large stirling engine? then you'd have to change the gearing/differential to make it not top out at like 16km/h. or maybe a small 2-stroke v8?
50cc 2-stroke 1 cylinder and power options would be 125cc and 150cc Edit: Needs also semi-auto option for ultimate rolling backwards the hill experience.
i remember someone in the megamod pack added a sports bike engine to the pigeon. 660cc 14k reving 180more or less hp engine.