The true facts of the matter: not all high performance 4 strokes are equal. some are reliable (Yamaha). 4 strokes get expensive after they blow up but will not blow up when some inexpensive measures are taken such as replacing worn valves, springs, pistons and cam chains. About the time a 2 stroke 250 needs a piston, replate, p/v seals ($350), a fourstroke should recieve a piston, fresh stainless valves & springs, camchain ($350). It is pretty much a wash unless you run your bike into the ground. In this case the 2 stroke will be cheaper to rebuild. By far the most important thing is buying a low hour, well maintained machine, and not whether it is a 2 or 4 stroke.