The truth on the YZM400??


25 replies to this topic
  • brentn

Posted October 27, 2010 - 02:25 PM

#1

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Does anyone have any specs on the YZM400 from 1997 that doug henry was riding?

I've heard all kinds of things from searching that it was

-426cc
-500cc
-550cc

and that it really was never a 400 at all despite what the model number is.
Also, did a yz400F ever win a championship in 1998/1999?

Just trying to put some things together here.
It seems finding this information is very hard and the general consensus on the matter is that it was a 400cc 4 stroke bike that won a championship....

  • gscx

Posted October 27, 2010 - 02:29 PM

#2

that bike is sick and basically a true works bike. I do know that a rider in Europe had the bike taken to a 500 or some huge number, at also had an aluminum frame. Did the AMA have the stock cylinder rule back then? That would make a difference

  • grayracer513

Posted October 27, 2010 - 03:19 PM

#3

The bike was a 400cc prototype that was totally unique, totally a works ride, and shared very little in common with the production 1998 YZ400F. The bike was essentially the brain child of a single Yamaha engineer who believed it could be done if the AMA would allow a displacement handicap. Yamaha approved the project, and ti was decided that the bike should have the smallest displacement the engineer thought he could get away with so as not to ask the AMA for too much and piss them off. 400cc was the size chosen.

As it turned out, the AMA, who had been trying to think of how they would deal with what they forsaw as inevitable government restrictions of two strokes because of emissions, never asked Yamaha how much they wanted and approved 550cc four strokes in the 250 class. Then they rethought it and retreated to 500cc. After they saw the bike run outdoors, and the screaming that came from the two-stroke camps, they backed away even farther to the current 450cc limit.

The bike did win an outdoor 250 championship in 1998, too.

From wikipedia:

"For 1997, Yamaha approached Henry with the idea of riding their prototype YZM400 four-stroke in competition. He accepted the offer. While he raced and led the early part of the 1997 Supercross season on a YZ250, Henry suffered a hand injury that forced him to withdraw during the middle of the series. He came back riding the four-stroke full time, and posted top-5 finishes at the first few Nationals, which was unprecedented for a four-stroke machine. Henry raced the bike at the final Supercross in Las Vegas, Nevada, and won the race in the prototype bike's first and only start. Tragedy would strike Henry yet again that summer, as he suffered two broken wrists at Budds Creek, mere feet away from the jump where he had his earlier injury. But Henry would battle back again.

"Henry would race the production version of the prototype four-stroke, the YZ400F, for 1998. This is the machine that started the four-stroke revolution in motocross. He battled through a strong but unspectacular supercross season where he finished 7th overall. The outdoor season would be Henry's chance to show the bike's true capabilities. After a win at his home track of Southwick, Henry followed up with a triumphant win in Budds Creek, the track that broke his arms and back. He would go on to defeat Jeff Emig, Jeremy McGrath, Ezra Lusk, Kevin Windham, Mickael Pichon, and Greg Albertyn, earning five overall wins in one of the most competitive seasons ever to take the 1998 250cc National Championship at Broome Tioga Sports Center. link Broome-Tiogs Sports Center He accomplished this with one whole round left."

http://en.wikipedia....nry_(motocross)

  • skoobeesnak

Posted October 27, 2010 - 03:43 PM

#4

I remember reading an article stating that it was always a 426cc that he raced and never a 400cc bike. If my memory is correct that came straight from Doug Henry in and interview. It was the bike that brought me back to offroad motorcycling after years away. I was considering the '99YZ400f or a KX500 at the time. I bought blue and have been very happy with it ever since.

I also seem to remember that Honda was lobbying hard for the limit to be 450cc as that was what they were developing.

  • brentn

Posted October 27, 2010 - 04:31 PM

#5

^that was one rumor I heard, another was that it was actually a 500. It would be nice to see an actual data sheet from yamaha on the bike, not likely to happen though.

I wonder how the current line of yz450's compare in performance to the completely custom works yzm400...

  • grayracer513

Posted October 27, 2010 - 05:46 PM

#6

I wonder how the current line of yz450's compare in performance to the completely custom works yzm400...

Having seen both, I can tell you that the 2006 YZ450 was a better bike than the YZM400 in many ways. The 2010 is better than that. Remember, the YZM was 13 years ago.

  • brentn

Posted October 27, 2010 - 06:22 PM

#7

Was it really a 3 speed tranny?

Where did you have the chance to see it?

Do you remember the gearing they were using?

Was it a 4 valve or 5 valve design?

  • bluethumper98

Posted October 27, 2010 - 07:32 PM

#8

I have a 98 yz400 and that thing is fast, brutal wfo. Not refined and developed like a new 450 but a great bike regardless.

  • brentn

Posted October 27, 2010 - 08:17 PM

#9

The yzm400 was 10 times the bike the yz400f was, would be nice to see exactly what it was capable of, like a dyno sheet! :excuseme:

  • Polar_Bus

Posted October 28, 2010 - 01:40 AM

#10

Was it really a 3 speed tranny?

Where did you have the chance to see it?

Do you remember the gearing they were using?

Was it a 4 valve or 5 valve design?


Many factory works Yamaha's use 3 speed trannies for supercross only tracks. No 4th gear(s), less ounces of weight...


I remember reading a mag tech article years ago on Tim Ferry's works supercross bike, and they commented it utilized a 3 speed. I also read some supercross pro's also use crazy odd gearing for supercross as well (like a 22T front sprocket) has something to do with "torquing" the swingarm (or lack of) through stadium whoops

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  • grayracer513

Posted October 28, 2010 - 06:26 AM

#11

Was it really a 3 speed tranny?

Where did you have the chance to see it?

Do you remember the gearing they were using?

Was it a 4 valve or 5 valve design?

As I recall, the SX bike was 3, and the MX bike was 4. Tim Ferry's '04 YZ450 was a 3 speed.

I saw the bike IRL at Glen Helen. Henry didn't win, but it was impressive. I've seen video of some of his other races that year. The current pro bikes are faster/better, trust me. Time goes on.

No idea on whether it was a 4 or 5 valve, although given that Yamaha was still pretty set on the Genesis concept at the time, I'd guess 5.

  • harrperf

Posted October 28, 2010 - 10:48 AM

#12

I heard rumor those bikes were RIGHT on the weight limit and that weight was ADDED where it was wanted for handling.

The last of the "truly" works bikes - although the RMZ 450 carmichael raced was quite unique too.

  • grayracer513

Posted October 28, 2010 - 12:07 PM

#13

I heard rumor those bikes were RIGHT on the weight limit and that weight was ADDED where it was wanted for handling.

There was a lot of "unobtainium" used in them, I'll say that.

  • jayh300

Posted October 28, 2010 - 12:14 PM

#14

There was a lot of "unobtainium" used in them, I'll say that.


nice term gray...:excuseme:

  • brentn

Posted October 28, 2010 - 01:03 PM

#15

can you imagine actually owning this bike?
It must be worth to a collector probably 50 grand. Would probably be worth that back in 98 considering all the custom fabbing and research that went into it by the best engineers at yamaha!

  • HRC

Posted October 29, 2010 - 04:24 AM

#16

In 1997...as you all know Doug Henry took care of the development of the YZFM 400 in US. In Europe Rinaldi Yamaha took care of the development of the YZFM 400 with riders Andrea Bartolini #5 (Italy) and Peter Johansson #6(Sweden).

From what I remember, Swedish rider Peter Johansson said in interviews....that the YZFM was a 400cc...and nothing else.

One of thoose ultra trick YZFM 400cc bikes had the cost of around 300000 $. Ofcourse...in those numbers where mechanics and development people included.


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The YZFM is still alive though here in Europe.....Rinaldi Yamaha have been taking care of the development ever since 1997 to this day.



A little off topic.....vintage:

YZM500cc 1988

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Edited by HRC, October 29, 2010 - 04:50 AM.


  • Polar_Bus

Posted October 29, 2010 - 04:56 AM

#17

can you imagine actually owning this bike?
It must be worth to a collector probably 50 grand. Would probably be worth that back in 98 considering all the custom fabbing and research that went into it by the best engineers at yamaha!


I believe "technically" works R&D raced bikes are supposed to be "destroyed" when retired, however...... many restored "works" vintage bikes are begining to surface into the hands of collectors..

  • HRC

Posted October 30, 2010 - 11:58 AM

#18

Sorry...I´m going to hijack this thread with some amazing photos of the YZM500cc from 1988 that I found....

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Bring back the real factory machines !!!!!!!:excuseme:

  • brentn

Posted October 31, 2010 - 11:29 AM

#19

WOW! We were discussing this in the two stroke forum about how Yamaha never made a 500 only the 490. Truth be told, they did!
Look at the jug on that thing!
Looks like someone privately owns it in those photo's, one lucky person right there!

  • SEOINAGE

Posted October 31, 2010 - 05:50 PM

#20

Seems like an awesome 500 right there. Do the short shorts go with it?





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