while on the topic of motorcycles in general...

this article is pretty damn scary
http://www.engr.colostate.edu/comm/n...n&cat=8&id=117

and i quote
"In the developed world, nearly all vehicles are powered by cleaner four-stroke engines. However, in developing nations, two-strokes are favored for personal transportation due to their low cost, durability and high power-to-weight ratio," said Lorenz. "Unfortunately, the simple two-stroke engine has so much pollution that one small tricycle may produce the same amount of pollution as 30 to 50 modern automobiles. The 250,000 tricycles in Manila contribute pollution equivalent to 10 million Honda Accords."