Two Strokes Are Better Here's Why
First off there is the simple power to weight issue. The above statement is incorrect, "not only is their power to weight ratio on par with the 2 strokes" since we are simply talking about two stroke vs. four stroke and not about ludicrous AMA rules. It is only fair to compare a 250cc two stroke against a 250cc four stroke instead of a 450cc. The two stroke is still king by far.
I also think it is incorrect to state that it is an environmental issue since these are closed course race bikes and not subject to emission testing. On that note I have found that currently the four strokes are much more offensive when it comes to noise pollution.
As far as engine pollution, it is a thing of the past. The semi direct injection and direct injection two strokes have already been integrated into other power sports and have proven that the two stroke can be not only lighter and more powerful than the four strokes, but also attain higher emissions standards and very similar fuel consumption.
For example, in the snowmobile world Skidoo launched the first semi-direct injected snowmobile years ago. And this year they are releasing a direct injected model. Artic Cat has had electronic fuel injection via throttle body for 27 years!! Of course you wonder how come my bike doesn't have it? There are several reasons, none of them how ever, are because four strokes are better.
A short list: The AMA allows a double displacement advantage in the lights class for four strokes and a 200cc advantage in the supercross class. This is just one example of the short sight of the AMA. Another reason is four strokes make manufacturers lots of money. When everyone saw what was winning on TV they went and bought one.
Now many people are in fact shifting back to the two stroke for several types of GNCC/woods racing.
Another benefit of the two stroke is the cheap and easy maintenance. The four strokes have gained considerable power and lost a considerable amount of reliability. They also require constant adjusting of the valves on top of normal upkeep. If you blow up or just decide to replace your top end in your two stroke your looking at est. $80 to worst case $500 dollars of damage. On a four stroke engine rebuilds may be fewer but if you burn up a four stroke you may be looking at a $1500 dollar bill. That will cover some enthusiast’s two stroke costs for a few years!
The after-market is also making a killing on four stroke parts, over 5 times the price for an exhaust that is easier to fabricate? See a trend?
Personally, I don't care what bike anyone rides, but four strokes, the AMA, and even the manufacturers to a point are killing our sport. It is becoming an elitist activity just to ride and maintain a dirt bike let alone race. What if the AMA does a 180 and gives two strokes the advantage? Many people won't be able to afford the switch back since many don't budget to buy a new bike every year.
If the manufacturers finally make the decision to use the technology that has been sitting on the shelf for twenty years, “although they will say it is the latest breakthrough" then 3/4 of the complaints about two strokes will be gone. You will have a high performance, lightweight, efficient, and cheaper alternative to four strokes. Not to mention how much quieter they are. But the longer they wait the more money they can suck out of their four stroke campaign.