What??? Racerhead #13

[JohnN]

Here is the reason that the four-stroke is killing the two-stroke, statements like this from MX Sports Marketing Director Nick McCabe. He was talking about the new KTM electric and equated it with the 2 vs 4 debate..

"There is a real race for each of these companies to develop the battery technology, as once the battery life becomes a non-issue it can then be transferred over to automobiles, which could eventually do to cars what the four-stroke did to the two-stroke if the world of off road dirt bikes - but that is still a very long way off. One fun fact to keep in mind: Honda, Suzuki, and BMW were motorcycle manufacturers long before they ventured into automobiles, and KTM, with their unique Xbow vehicle, is no stranger to taking chances. "

Please head over to the Racer X Online site and tell them what you think...

http://www.racerxonline.com/article/racerhead-13-03-26.aspx

[JETZcorp]

If electricity does to cars what the 4T did to motocross, we might just have to give Detroit a few more bailouts.

[Chris2T]

the 4 stroke did nothing to the 2 stroke, only legislation did

[JETZcorp]

That is true.  When they were allowed to compete head-to-head at equal displacement, the two-strokes absolutely wiped the thumpers out, to the point that no one even thought of racing a thumper until the double-displacement rule took effect.

[offroader]

The double displacement rule was always in effect as far as i remember.At least in the original 250 class.If memory serves me the displacemnt limit used to be 500 or 550 for the old style 4 strokes.Once Yamaha came out with the 400f and the rest of the manufacturers started making the new style f1 based 450's and told the buying public they are the very best that is when the 4t's took over.The buying public falling for the latest and greatest and not buying 2t's is what killed the 2t.At least here in the USA.

[JETZcorp]

I don't know how far back you're remembering, but it was equal displacement right 1996.  At that point, I think it became 250 vs 550, but when KTM rolled out a 525 and murdered the Japanese on paper, that was rolled back to 450.  That's going from memory, though.

By the way, has anyone read the Wiki article on the YZ450F?  It's a joke.

The Yamaha YZ400F was developed to fit into this category. It solved the power dilemma by borrowing superbike technology and giving the YZ a five valve head, liquid cooling and a 12.5-1 compression ratio.

Excuse me, but precisely how does water-cooling give it an advantage over... water-cooled two-strokes?  Let's not forget that the magical five-valve head was replaced with a four-valve for the 2010 model, as pointed out and praised in that article!  Growl!

[JohnN]

The double displacement rule was always in effect as far as i remember.At least in the original 250 class.If memory serves me the displacemnt limit used to be 500 or 550 for the old style 4 strokes.Once Yamaha came out with the 400f and the rest of the manufacturers started making the new style f1 based 450's and told the buying public they are the very best that is when the 4t's took over.The buying public falling for the latest and greatest and not buying 2t's is what killed the 2t.At least here in the USA.

The double displacement rule came into effect in the early to mid 1990's as I understand... I have looked for the rules and have not been able to find and confirm this though. If someone does know, please post it here.

At the time the rule was passed no one thought that the 4 strokes would beat the two-strokes even with the displacement advantage. Then a lone Yamaha engineer took it upon himself to build the very first modern four-stroke motocross bike. When he brought the idea to his bosses they just laughed at him at first... t took a while before they got behind the machine...

Then when the four-strokes were still having problems beating the two-strokes, the AMA put into effect the unleaded fuel rule, which gave the four-strokes even more of an advantage.

The first racers to switch over to the four-strokes were the vets... it was easy to ride. Then as more and more showed up at the track and began doing well, more people bought them and bought into the whole four-strokes are better marketing hype... sales of two=strokes all but disappeared.

Over the past two years there has been a shift in this situation... while not every single four-stroke is a time bomb, enough were to force some people out of the sport all together and others to seek out alternatives. The two-stroke has begun to look like a great machine again. Light, fast and fun...

2010 will be a banner year for two-strokes... it's happening already!

[JETZcorp]

The rule change was 1996 according to Wiki, but the citation is a dead link, so yeah.

[opfermanmotors]

[JETZcorp]

Well, there we go.  The fact remains, if you were stupid enough to want to enter a 450cc four-stroke in professional motocross in, say, 1980, you'd have to face off with 440 Maicos and YZ465 two-strokes.  It wouldn't even be like shooting fish in a barrel.  It'd be like shooting a barrel of fish.  With a GAU-8.

[opfermanmotors]

1997 June American Motorcyclist states that the rule was actually perhaps in 1994 and it was for 550cc (which is why Yamaha was 150cc below the actual limit with the 400).  It also loosely implies the arbitrary 550 was because well, you fire every other revolution   But I speculate there.  There were also weight requirements, etc. for the 400 but those are irrelevant here anyway.

So, the context of interest from that magazine:

"By 1994 there was renuewed interested in developing four strokes, so the AMA raised that displacement limit.  Since then, engines that hit once every other revolution have been allowed to grow to 550cc in the 250 class.  That rule has attracted four-stroke entries from smaller manufacturers-Husaberg and KTM."

[opfermanmotors]

Please note that the article states there was little interest until 1997 from the bigger japn companies, almost implying the rule change may not have been forced by the big 4.

[opfermanmotors]

actually, let me read this a bit more, you can find the issue it's page 28.   Anyhow, what I piece together a summary:

1994 -> Rule change, 4 jokes = 550cc
Jap companies do not compete though because they do not want to gamble.  Rule book states yo umust produce at least 400 bikes production a year of that bike or whatever to compete.
1997 - AMA says hey, let's let you guys around that rule, have a 1 year exception.  Yamaha says, OK, thanks AMA, I'll produce a 400cc crap bike and beat smaller displacement bikes. 

Wow that worked.  And so it shall be done.

[JETZcorp]

That's surprising.  Knowing Honda's history with four-strokes, I would've expected them to get all wide-eyed, carve a big chunk of the Civic engine and stick it in a bike the instant the rule change was announced.  It is rather curious that Yamaha were the ones to start the four-stroke thing, and now they're the only major Japanese factory to keep trucking on with the two-strokes on a large scale.

On the subject of Japanese bikes, I just want to see Kawasaki return to the rotary-valve two-stroke.  Those engines were so mean, you just couldn't believe what you were watching.  We're talking about 100cc flat-trackers with full-grown men on them screaming around corners sideways, then pulling the front-end up on the straight.  Man, I'd like to get me a 100 Green-Streak, but I digress (fairly often, apparently.)

[opfermanmotors]

Ya, still can't find a definite reference for 1994 aside from that one, of course the 1996 rule is all hearsay.  Given what the mag says I think it's strong for a 1994 intercept and the speculatio around 1996 was due to Yamaha taking advantage of it only in 1997, which was actually due to another special rule, unless both rules came at the same time.  Although, it states smaller manufacturers were taking advantage of it, so had to have some time to do that before hand.  We can see if KTM or Huesaburg were competeing in 250 class with larger 4 strokes in 94-96 era.