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they do that exhaust like that to make it act like its a longer header for more torque. it adds a vaccumm effect. they do that on briggs 5hp headers to give it alot of torque but still get good high rpm hp.
 

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That's a sweet rig but they may not have sold as many as you might think. In 87 Kawie dealers were begging folks to take their left over 86 KX 500's...
 

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what I don't understand is why they ditched the YZM500 and kept the 490?? yes, the frame wasn't good on the 500 and the power output was scary, but the 490 was even worse, it had no rideability whatsoever and power was next to useless.

if yamaha had released this bike into production it could have sparked new interest in the open class and thrown the big four into a tech-race giving us 500cc's that was technological on par with the 125's and the 250's of the era, possibly never killing the open class at all...
 

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yamaha did try to get the 500 goin again in 91 with theyr wr500 but it was air cooled...correct me if im wrong but they baically made that to replace the 490 i believe is what theyr plans were...they only made the wr500 for 3 years because it didnt really take off as planned...looks basically the same as the yzm heres a pic...



 

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what I don't understand is why they ditched the YZM500 and kept the 490?? yes, the frame wasn't good on the 500 and the power output was scary, but the 490 was even worse, it had no rideability whatsoever and power was next to useless.

if yamaha had released this bike into production it could have sparked new interest in the open class and thrown the big four into a tech-race giving us 500cc's that was technological on par with the 125's and the 250's of the era, possibly never killing the open class at all...
I agree completely!

But if I remember right Suzuki wanted nothing to do with the open class either? In the end ama was the one that hammered the final nail in the coffin, but the manufactures did nothing to stop it.
 

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I agree completely!

But if I remember right Suzuki wanted nothing to do with the open class either? In the end ama was the one that hammered the final nail in the coffin, but the manufactures did nothing to stop it.
ama closed the open class under pressure from both yamaha and suzuki, suzuki tried getting into the open class with the rm500 in '85 i think but failed miserably thus stopping production of the 500 after a few years, yamaha teamed up with suzuki 'coz they knew the 490 was getting stomped on by the reds and greens.

yamaha should have given the YZM another year of R'nD and then released it, this would should have been enough to make honda and kawa update theire 500's, sales would have gone up and suzuki would have realized that there actually was a market for open-class bikes after all and joined in.
that way they would have kept updating the 500's every year like they did with the smaller bikes, and the YZ400F would have never seen the light of day...
1998 is kind of a D-Day for the 2-strokes...

just imagine if the big four had kept updating the 500's all the way until now.
we would have seen sophisticated, powervalved, alu-framed 2-stroke monsters from all the japs, Red, Green, Blue or yellow, your choice...
 

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4stokesLazy2strokesCrazy!
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yamaha did try to get the 500 goin again in 91 with theyr wr500 but it was air cooled...correct me if im wrong but they baically made that to replace the 490 i believe is what theyr plans were...they only made the wr500 for 3 years because it didnt really take off as planned...looks basically the same as the yzm heres a pic...



The wr500 IS a 490.
 

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ama closed the open class under pressure from both yamaha and suzuki, suzuki tried getting into the open class with the rm500 in '85 i think but failed miserably thus stopping production of the 500 after a few years, yamaha teamed up with suzuki 'coz they knew the 490 was getting stomped on by the reds and greens.

yamaha should have given the YZM another year of R'nD and then released it, this would should have been enough to make honda and kawa update theire 500's, sales would have gone up and suzuki would have realized that there actually was a market for open-class bikes after all and joined in.
that way they would have kept updating the 500's every year like they did with the smaller bikes, and the YZ400F would have never seen the light of day...
1998 is kind of a D-Day for the 2-strokes...

just imagine if the big four had kept updating the 500's all the way until now.
we would have seen sophisticated, powervalved, alu-framed 2-stroke monsters from all the japs, Red, Green, Blue or yellow, your choice...
ah ok my thinking was on the right path just backwards lol

I agree its really a shame the way things happend..
 

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if im thinking right the wr is a bit different i think they changed the stroke and the tranny...but i might be wrong...iv been known to do that sometimes...lol...
it's the same engine in both the YZ and WR, they just tried to update the chassi and handling.

but from what I've heard the WR was actually more dangerous to ride than the YZ490? anybody ever ridden one?
 

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4stokesLazy2strokesCrazy!
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if im thinking right the wr is a bit different i think they changed the stroke and the tranny...but i might be wrong...iv been known to do that sometimes...lol...
It has the same bore/stroke and is 487cc's as the 490.
Wiseco sell pistons for both with the same part number.
You might be on to something with the gear ratios in the tranny Yamaha is known for changing the ratios in the gear box and then calling the entire motor something else lol

The IT490/YZ490/WR500 are all the same motor.
Hells even the IT465/YZ465 is the same bottom end- you can bolt any IT/YZ/WR 490 top end right on the 465.

That's whats so great about them!
My own lil YZ400 has a YZ case with the IT gears, the IT's lighting coil, and the clutch and presure plate from a Banshee with R1 springs :)
if I wanted to I could also bolt on the top end of an IT425 and bore to a 450.
But I haven't found pistons to do that.....
 

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The IT490/YZ490/WR500 are all the same motor.
Hells even the IT465/YZ465 is the same bottom end- you can bolt any IT/YZ/WR 490 top end right on the 465.
Why would anyone want to do that? The 465 is a better balance between bore and stoke, they have less vibration, were easier to tune, and ran slightly cooler. That's the reason why I'm putting a 465 top end on my yz490 motor.

My own lil YZ400 has the clutch and pressure plate from a Banshee with R1 springs :)
Good to know...... Looks like a billet clutch basket is in my future.
 

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Bump here you go roach.................:thumbsup:
 

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It has the same bore/stroke and is 487cc's as the 490.
Wiseco sell pistons for both with the same part number.
You might be on to something with the gear ratios in the tranny Yamaha is known for changing the ratios in the gear box and then calling the entire motor something else lol
QUOTE]

from what ive heard in the time that i owned mine and looked for any info on it i could(very limited) they suposedly made it have a wider ratio tranny for open woods and fast outdoor tracks...but thats just what iv heard...
 

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it's the same engine in both the YZ and WR, they just tried to update the chassi and handling.

but from what I've heard the WR was actually more dangerous to ride than the YZ490? anybody ever ridden one?
yeah i owned my wr500 for about 4 years and loved it tons of power everywere im a big guy(upper 200lber) and it would roll back on the back whell with a simple twist of the throttle in 4th gear...only downside is not much info readily available...
 

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I had heard about the yammi 500's, and i knew they were very limited, but not exact numbers.

there are also RM500's floating around out there.

the CR has a 583cc bigbore out there now. i believe CPI makes it.
that would be INSANITY
 

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nah...insanity is the maico 625 and 700's...

those ATK intimidators only have low 80 HP stock. no aftermarket either. but the powerband is probably wider than a 4 stroke......

getting 100HP out of a CR500 is extremely hard, however the 500 Saber for the 250R pulls 100HP all day long. a properly designed 583 would pull 120+ HP no problem.
 
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