How much power is needed?

[robispurple]

Hey, I want to make an off road two seat go kart/buggy. I've been looking at all different kinds of engine setups. Horizontal engine, single cylinder dirt bike engine, and even street bike engines. I want the engine to be strong enough to push the kart(i don't know how much it will weigh maybe 200lbs) and two average sized passengers(150lbs) at, at least 25-30 mph. I'm not sure whats best please provide your opinion and experience. I'm a first timer when it comes to the kart world. Thank you for your help.

 

[Doc Sprocket]

I really believe you should have the overall design pretty much nailed down before making a firm decision on the engine.

Without much further information, I'd say a bike engine is the best bet.