ttoks

with current 4 stroke engines, you will struggle to get a good enough power to weight ratio to get good performance, however if enough time was put into developing a good 4 stroke, you will have a very good engine, a great example is dirtbikes, which were, up until ten years ago an all two stroke affair, until the yamaha YZF400 was introduced, not as ft as the two stroke of the time, but it got peoples attention, fast forward to today, and 450cc 4 stroke are absolutely dominating the 250CC class so badly there aren't any competitive 250 two stroke in it anymore, and so starting in 2010, it will be 350cc 4 stroke to 250cc two strokes, it isn't a case of 4 stroke need to be twice the size to make the power, thats far from true.

IF the development is put into making an overhead cam, 4 valve big bore (as in large bore to a short stroke) 4 stroke, which uses a self contained lubrication system to remove all oil from the fuel, it will be a case of .40 4 stroke competing with .21 and .28 two stroke engines.

for amusement, heres a pic of a revo with an O.S .52 (not a .90, silly me[sm=bananahead.gif]) 4 stroke in it, which is actually competitive with the two strokes.