When did the Mx 4t limit change from 550 to 450

skiz
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skiz
The link below shows a page from, I believe, the 1997 AMA Mx rule book which shows a 4t limit at 550cc. What year was the limit lowered to 450.?
https://comoto.imgix.net/blog_content_image/image/41356/gallery/AMA_rul…
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cwtoyota
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cwtoyota 3/28/2020 2:06pm
3/28/2020 2:06pm
skiz wrote:
The link below shows a page from, I believe, the 1997 AMA Mx rule book which shows a 4t limit at 550cc. What year was the...
The link below shows a page from, I believe, the 1997 AMA Mx rule book which shows a 4t limit at 550cc. What year was the limit lowered to 450.?
https://comoto.imgix.net/blog_content_image/image/41356/gallery/AMA_rul…
My memory says it was for the 2003 season.
ATKpilot99
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ATKpilot99 3/28/2020 2:10pm
3/28/2020 2:10pm
skiz wrote:
The link below shows a page from, I believe, the 1997 AMA Mx rule book which shows a 4t limit at 550cc. What year was the...
The link below shows a page from, I believe, the 1997 AMA Mx rule book which shows a 4t limit at 550cc. What year was the limit lowered to 450.?
https://comoto.imgix.net/blog_content_image/image/41356/gallery/AMA_rul…
cwtoyota wrote:
My memory says it was for the 2003 season.
Pretty sure you're correct. They also started allowing 450s in the 250 class in the GPs that year.
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ShipLap
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ShipLap 3/28/2020 2:20pm
3/28/2020 2:20pm
According to Todd Jendro, they (the AMA) made a mistake in allowing four strokes to have an almost 200% displacement advantage over two strokes. By the time they realized the mistake, they lacked the will to correct it.
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skiz
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skiz 3/28/2020 3:11pm
3/28/2020 3:11pm
I think this is the sequence

1993 last year of the AMA 500cc
1994 first year that 550cc 4t is allowed in 250cc class but 400 unit production was also required
1997 continued to allow 550cc 4t in the 250cc class but EXEMPTED production requirement until 2nd year of competition
2003 limit was reduced to 450cc 4t in the 250cc class
2006 that class was changed to MX class
2009 that class was renamed 450cc class

2003 FIM changes their class names to Mx1, Mx2, Mx3 and cc limits for 4t are increased to 250, 450, and 650. Limits for 2t remains 125, 250, and 500
2014 Mx3 is gone and Mx1 is renamed MxGP
cable
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cable 3/28/2020 4:03pm
3/28/2020 4:03pm
brings back memories of guy cooper pulling holehsots on the 540cc ktm at 40 something years old.
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Johnny Depp
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Johnny Depp 3/28/2020 8:35pm
3/28/2020 8:35pm
Ask John Dowd.. He's the reason the rule was changed. Hole Shot King!



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scott_nz
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scott_nz 3/28/2020 9:10pm
3/28/2020 9:10pm
cable wrote:
brings back memories of guy cooper pulling holehsots on the 540cc ktm at 40 something years old.
Shayne King ran the supercross series on one as well,
Ryan625
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Ryan625 3/28/2020 9:24pm
3/28/2020 9:24pm
cable wrote:
brings back memories of guy cooper pulling holehsots on the 540cc ktm at 40 something years old.
That was my first thought when I saw this thread. Pulled them by miles lol

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