what started the 4 stroke revolution?

[spoolin7]

i haven't really followed dirt much the past few years, but i've tried to keep up with some of the stuff that's going on. i know the 4 strokes have pretty much taken over, which i used to think was a good thing until i recently got my first 2 stroke. not saying the 4 strokes don't still kick ass, cuz they do. i just used to hate 2 strokes until recently.

anyways, who started the whole thing? i know yamaha came out with the first 4 stroke moto-x bike, then honda soon followed. who started the push to get 2 strokes gone? and why?

 

[Octane250F]

Yamaha did. Basically when the YZ 400 came out in '98 and Doug Henry won the 250 National championship it ended the dominance of 2-stroke MX bikes.

 

[Rich Rohrich]

i know yamaha came out with the first 4 stroke moto-x bike,

Husqvarna and Husaberg had competitive big bore four-stroke MX bikes long before the YZ400F was even an idea. Yamaha merely made them reliable and affordable.

 

[trial_07]

That yamaha 426 wasn't too reliable!

 

[Rich Rohrich]

That yamaha 426 wasn't too reliable!

The steel valve YZF 400 & 426 are the most reliable engines of the modern era.

 

[Octane250F]

That yamaha 426 wasn't too reliable!

A riding buddy of mine just sold a '01 YZ 426 that was bored out to a 444. The guy who owned it before him MX raced it for 4 years in 250 A and never had to rebuild the motor. It still started on the 2nd-4th kick and didnt burn oil. It was very fast too. :cool:
Id say it was pretty reliable.

 

[OldTimer]

My question is when was it decided that the 4 stroke could compete at 450cc verses 250cc 2 stroke? I suspect that 4 stroke dominance would shortly follow that ruling. Or perhaps that it took some time to develop a 4 stroke that could perform at the current level even with the displacement advantage.
So which was it, the chicken or the egg?

BTW - Hooray for me! For the first time ever my post passed the spell check on the first run!!! :nod: :cool: :) :ride:

 

[XRpredator]

My question is when was it decided that the 4 stroke could compete at 450cc verses 250cc 2 stroke? I suspect that 4 stroke dominance would shortly follow that ruling. Or perhaps that it took some time to develop a 4 stroke that could perform at the current level even with the displacement advantage.
So which was it, the chicken or the egg?

It was the chicken.

Prior to '97, when Henry ran the pre-pro OWH2 (YZ400F), the AMA set the displacement "advantage" at 540cc. Lance Smail was actually the first guy to qualify for a supercross main back in '97, but it was the Daytona SX, and there was a different qualification system back then to get 30 riders in the main. Heck, he got third in the LCQ at Seattle on his one-off KTM540. (you shoulda heard the guy on the Husaberg peggin' the rev-limiter in the day qualifiers!)

Guy Cooper ran a KTM540 in 2002 and garnered several holeshots during the outdoor season. Not bad for a guy over 40. The 'advantage' was lowered to 450cc in 2003.

 

[FD6MD]

The advantage was actually 650cc for a long time.

It was lowered to 550cc in the mid-late 90s.

 

[motometal]

My question is when was it decided that the 4 stroke could compete at 450cc verses 250cc 2 stroke? I suspect that 4 stroke dominance would shortly follow that ruling. Or perhaps that it took some time to develop a 4 stroke that could perform at the current level even with the displacement advantage.
So which was it, the chicken or the egg?

BTW - Hooray for me! For the first time ever my post passed the spell check on the first run!!! :nod: :cool: :) :ride:

spell check? seriously? I didn't even know you could do that...

 

[OldTimer]

The advantage was actually 650cc for a long time.

I can see why. I had a '93 Suzuki DR650 and one day ran across a guy riding a YZ 250. He smoked my head on the trails, but I was certain I'd take him on the street as we sprinted to another set of trails down the road. I speed shifted whilst revving the nuts off my bike all the way down the road and that YZ passed me like I was on a bicycle. I decided then that I was done with four strokes. I realize that that model wasn't designed to RACE anything, but geeze a 650 vs a 250?
Anyhow, 4 strokes have come a long way since then, but I'm still jaded.