Sorry, late to this conversation but I have to jump in. I did not read every single post so take this as a stand alone to the original comment and a few responses I perused quickly. Two stoke biases are cocooned in myopic and willful ignorance and/or not looking at the total picture. These aren't your grand daddy's piston port oil splattering 2 stokes. We're talking about insanely efficient, often orbital or direct injected machines with engineered oils that are burned at about a tenth the percentages of even 15 years ago.
A KTM 200 is an amazingly clean and efficient 2 stroke power creating device in relation to a similarly performing 4-stroke machine (an in fact similar power per pound is essentially NOT possible for a 4 stroke without some pricy exotica) . That "similar" performing 4 stroke will use FAR more exotic and expensive metals with very short service intervals necessitating their rather frequent replacement. Ever been to a titanium mining facility? I have. Trust me, environmentally speaking, It's like earth raping.
Now, I realize that little puffs of smoke are psychologically more disturbing to people but it's simply not "just" what you can see that represents pollution. Last time I checked, "For off road use only" 4 stroke motorcycles usually have whatever catalyst device they "might" have been delivered with removed. AND the Increased weight of that "somewhat" comparably performing (yeah, right) machine also means a lot more fuel used. And don't forget, the fuel going through that engine is in reality only a portion of the total pollution "footprint of the machine over it's life cycle (see titanium mining comment above).
Look at the total "footprint" (carbon and otherwise) of similar machines over the course of their entire "normal" operating lifecycle and you will get a VERY different picture of how dirty or clean they are. And by that standard a modern, lightweight, efficient recreational 2 stroke is at a minimum on par and usually far FAR ahead of the comparable 4 stroke bike. By that view a Prius is actually a fairly filthy vehicle (go look at a nickle mine and what those impacts do to the environment and explain to me how "clean" they are). And don't even get me started on the orbital injected hyper efficient marine outboards that the marine marketing departments just can't seem to get rid of despite decades of trying. In that world the 2-strokes are cleaner, more efficient, and far better performing by any measure and for some reason people just keep buying them. Go figure.
If it makes you "feel" better, get one of the newer off road electrics. They are actually getting quite impressive for closed course joy riding. Just don't go researching where they get all those rare earths and elements to build the batteries and components. It might upset you.
FloridaSteve screwed with this post 01-03-2013 at 12:13 PM