There's no way around the fact that two-strokes are becoming more rare, harder to find and increasingly obscure in the motocross world. It's a crying shame that so many kids don't get to experience what I call the "fun factor," namely hard-hitting two-stroke power.
Some freestyle motocrossers still recognize the advantageous power-to-weight ratio found in modern two-strokes. Considering the average stock 250cc two-stroke made in the last ten years has roughly 45 horsepower and only weighs about as much as a 250cc four-stroke. That's like having the same bike, only with seven or eight more horsepower.
Now, imagine taking a 250cc two-stroke and increasing its displacement by 50cc's. That's what MXA does to their KTM 250SX. Check it out to learn more. Motocross Action Magazine, April 2010 issue, pg. 164. Just flip to the glossary and click on the article "We Build a KTM 300SX Big Bore."