Although you are right about it not being quite that simple anymore, your example is bad.

The YFZ450 is in a high state of tune from the factory.
The Banshee has a motor developed in the 1960's, and in an extremely tame state of tune... on top of that.

Mod the banshee so that both motors are in equal states of tune in relation to their top potentials, and see which is more powerful.

Example: on a scale of 1 to 10, 10 being absolutely modded to the max, the YFZ engine is probably a 7 completely stock, with little to extract.
On this same scale, the banshee probably comes from the factory as a 2, of 10.

Mod the banshee motor to 7/10's of its top potential, and race the hill. Here we have a better comparison of 2 stroke vs 4.

 

the banshee may get more horsepower , but the yfz will get all the torque and we all know wich one will get the tire to hook up, the yfz. i have built both and the banshee will look awsome on a dyno but put them side by side in the real world and it takes alot more horsepower from a 2 stroke to compete with a lesser 4 stroke. the power has got to be controlled and not just spin the tires my yfz with a little under 60 horse has no problem beating my buddys banshee with around 80 horse.

 

Never does a race come down soley to how many ponies you have, The moment you start spinning your done.

 

Where I ride.... Glamis, Dumont, Pismo, Its ALL about the "ponies".
Traction isnt a problem. Thats what paddles do.

 

Im not a sandman, but it never hurts to have 50-55hp haha

 

bro, if you havnt....

you MUST experience THIS

and THIS.

and lastly, this one.

These are some pictures I took my last dumont trip.

edit> that spot where I took all those pictures is WAY up there... very high.
Numerous ways to get up, but there is one face that runs ALL the way up, and it is extremely steep.
Just the ticket for the KX500 with 10 paddle. [img]i/expressions/face-icon-small-smile.gif[/img] (I dont know that guy on the red bike, btw. All the dunes, and he rides up next to me)

 

Stock for stock in a 1/4 mile pavement drag I think it would be a close match. On dirt I think a newer 450 would take the lead until they hit their top speed then the 500 would go by pretty quickly.

But this is about a 426 and I think a CR500 would walk the 426 fairly well regardless of where the race takes place.

As for the dyno charts, I have seen the 500 2-strokes anywhere from 48 - 60hp stock. With the 450's around 45 - 55hp stock. So they really are fairly close on a dyno.

About the street bikes doing over 100 in first well ... they can and they do. The new ZX10 I beilieve does 110 in first. I know for a fact that an 05 R1 does 107 in first banging off the rev limiter.

Also keep in mind that the 500 2-strokes are designs from the mid 80's. Some of the new 250 2-strokes make just as much power as the 500's.

 

KX500's put out big juice! 63-65hp stock from the factory. Dont forget that two stroke motors have higher power-to-weight ratios than four strokes. And rev alot higher!

 

Not true, and NOT true.

Not speaking of CR500's, as I have little experience with them. But, my 93' KX can and does eat the 450's alive. The 450's are fast, yes indeed. Fast enough to compete with 250 2 strokes on a track. (faster than the 250 2 strokes, not as fast or powerful as the CR/KX500)

Your second comment is completely untrue. There is NO 250 that makes the power/torque, or is in the same league as the big bore, powervalved 2 stroke KX500.
The CR500s were toned down as the years went by, making the 1985 CR500 the most powerful.
KX500s are the same, most years. Engine unchanged. They are powervalved, and really fast. 250's, even brand new, arnt even comparable.

 

i agree i ride 80% in the sand and i love the dunes here in utah and have had many 2 strokes, then the raptor came out and i had to have one and started missing my 2 strokes and swore i wouldnt buy another 4 stroke then rode a cannondale and loved it then the yfz came out and now i love it and the dale and the yfz rev very fast and very high almost have that 2 stroke feel with a bunch more torque and as far as power to weight most the new 450,s have more power and comparable weight to make them really go. but do i think 2 strokes are coming to an end, no way to much new 2 stroke sled engines are now burning clean and pumping out a ton of power so im sure one company will go against the grain and suprise us very soon.