Ok, I know how to ride quads and all that but what exactly is in the interals? I know all about car/truck engines.....especially the hemi engine, but i dont know chit about atv engines.

Is it with the smaller engines, 1 piston (combustion chamber) and with the bigger quads, two? I noticed with the 400exs, they can run dual exhaust since they have to exhaust ports. Does that mean that theres 2 combustion chambers? Can you guys just help me out with the basics of it? You don't have to explain how it works, just wondering what the hell is inside these haha. thanks