Did yamaha have it right the first time?

This is a very good article on the history and development of the four stroke in the modern era:

https://motocrossactionmag.com/supercross-history-the-bike-that-time-fo…

However what that article doesn't address is the yamaha side of things. In the mid to late 90's KTM was still a fledging niche company. Yamaha and the Japs were giants. Yamaha pushed for the four stroke rule with the AMA to begin with. Yamaha used 400cc as the building stone for development with Doug Henry. Through race testing and feedback from the public Yamaha decided that the 400 just wasnt quite enough. It still gave up a lot against the 250 two strokes at the time. If it was dry and hard pack (vegas '97) the 400 could match and beat the 250 two strokes. However if it was deep, soft, and loamy (aka TRACTION) the 400 struggled.

Yamaha then developed and created the most powerful engine Ive ever experienced, the YZ426. I remember my 01 YZ426. It didn't handle the best but jesus that thing had TOO MUCH power. The feeling was unanimous from testers to magazines to the general public. Even Button/Henry made comments about how difficult it could be at times to handle. The 426 only lived a couple years before Yamaha released the 450 in 03.

Dont forget Honda was developing their four stroke and Ryan Hughes raced the honda 450 in 01. The bore and stroke in the honda 450 was more of a torquey linear motor where as the 426 was more of a revver. The two bikes were very different. The reception to the honda motor and powerband was a lot more popular than the yamaha. Yamaha made the decision to increase bore and decrease stroke to achieve 449cc. The result was a much more managable and easier to ride bike.

At the time it didnt make sense. A 450 that is easier to ride and more manageable than a smaller 426? Yes. The 450 feels less powerful than the 426? yes.

This all came about in a relatively short time frame. Before the better valvetrains, higher compression, fuel injection, and pumper carbs the four strokes really did give up a lot to the 250 two strokes. It wasn't until the engines got lighter, the rotational masses got lighter that the four strokes started to flex their muscle by being bigger. The advent of better carbs and then fuel injection really made the four strokes shine. Now the modern 450 four stroke is torquier, snappier, and revs faster and further than those first generation four strokes.

Had the powers that be knew then what we knew now, the max displacement CC rule would have been much different. The manufacturers pushed for 550cc because they knew then with the technology available, and power to weight ratio it was 2 four stroke cc to every two stroke cc.

Now 250cc four strokes make more torque and HP than even the most modern 250cc two stroke.

So no, yamaha did not have it right the first time. Neither did KTM.