Author Topic: Pre '75 legal ?  (Read 4986 times)

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Offline Husky500evo

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Pre '75 legal ?
« on: July 09, 2008, 09:31:34 pm »
I have aquired a '75 TNT 250 , which is pre '75 class legal going by the MA rulebook . The bike doesn't have a pipe at the moment , so I need to chase one up . My question is , can I use an up-pipe on this bike & still be legal ? Or do I have to find a photo of Jimmy Ellis or someone back in the day using an up-pipe , to be able to use one . In the MA rulebook it states at 18.3.0.4  that the exhaust may be modified but must generally follow the original lines . I have seen other brand pre '75 bikes ( that originally had down-pipes ) with snail pipes & up-pipes , but the owners maybe had documented proof that they were period legal . My reason for prefering an up pipe is not for performance gain , but rather for practicality, as most of the tracks in my area are not very down-pipe friendly. I also think that an up-pipe looks better . I have a picture of a TNT with an up-pipe that I will try to post . Unfortunately this picture has only been taken recently.
« Last Edit: July 09, 2008, 10:06:26 pm by Husky500evo »

Offline Tim754

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Re: Pre '75 legal ?
« Reply #1 on: July 09, 2008, 09:38:42 pm »
You have a dated piccy of the pipe type you want? That sounds like proof to me.  ;)Old magazines (hopefully with date of printing somewhere )are a great source of reliable info to back you up.  Cheers Tim
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Offline Tim754

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Re: Pre '75 legal ?
« Reply #2 on: July 09, 2008, 09:41:01 pm »
Hold it "1975 TNT" Firko ,somebody what Can Ams are kosher in Pre75 . I seem to remember some specified models as no go. Tim
 Ahh is Good I just found the book and looked,,,,,,,,, Husky you MUST have a !!!!!! 1974[ Model !!!!! OK
« Last Edit: July 09, 2008, 09:45:55 pm by Tim754 »
I may not agree with what you have to say, but I'll defend to the death your right to say it.
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Offline Husky500evo

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Re: Pre '75 legal ?
« Reply #3 on: July 09, 2008, 09:43:43 pm »

This picture came from the Swedish Can Am site , which I was directed to by forum member Kawboy a while back . The guy standing behind the bike is none other than Swedish former World Champion , Bengt Aberg . The pipe appears to be off an MX3 Can Am & the sidepanel maybe off a mid '70s KTM ? But I think that it looks ok apart from the seat cover & the front guard .
« Last Edit: July 09, 2008, 10:04:00 pm by Husky500evo »

Offline Husky500evo

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Re: Pre '75 legal ?
« Reply #4 on: July 09, 2008, 10:02:00 pm »
The way I understood it was that the TNT 175 & 250 were models that remained unchanged after '74 ,therefore being eligible .

Offline Tim754

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Re: Pre '75 legal ?
« Reply #5 on: July 09, 2008, 10:31:31 pm »
Husky lets call your fine bike a "1974 follow on"  Please.  ;)
I may not agree with what you have to say, but I'll defend to the death your right to say it.
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firko

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Re: Pre '75 legal ?
« Reply #6 on: July 09, 2008, 10:56:40 pm »
I'm not certain whats legal or not but when the Can Am shitfight erupted at the Barabool Nats a few years ago, ALL Can Ams after the 31st of December 1975 cut off were excluded by chief scrutineer Peter Drakeford. I seem to remember that the thinking behind the decision was that the '75 model differed from the '74. I'm not so sure about TNT models but the MX1 (1974) and MX2 (1975) are very different engine wise. I don't recall the rulebook stating that the '75 TNT 250 was a legal flow on but it may have changed. I don't have the 08 book.

Offline Husky500evo

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Re: Pre '75 legal ?
« Reply #7 on: July 09, 2008, 11:49:29 pm »
My '08 MA rulebook says Can Am 175 & 250 TNT models only , in the list of eligible pre '75 machines .
« Last Edit: July 10, 2008, 10:00:37 pm by Husky500evo »

Offline holeshot buddy

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Re: Pre '75 legal ?
« Reply #8 on: July 10, 2008, 09:54:20 pm »
heres a piccy of a 75 canam tnt ;D
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Offline holeshot buddy

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Re: Pre '75 legal ?
« Reply #9 on: July 10, 2008, 09:56:00 pm »
and heres a piccy of a works canam ;D
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Offline Freakshow

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Re: Pre '75 legal ?
« Reply #10 on: July 10, 2008, 11:20:04 pm »
the whole up down thing is pointless i think.  THey made em both up and down prior to 74 so in theory you can have it anyway you dam well please. its only an exhaust pipe, if you get some peanut on your case you can use the ruling under a 'special', thereby any item pre 74 is legal, if you could have made it or bought it given its technology was put into pratice pre 75.  The ruling never states a component has to have been on that model bike prior to 75. it can be from any bike prior to 75. if your worrying still, just cut up a mx 250 or get a replacement made as one. 

Put the pipe where you like...
« Last Edit: July 10, 2008, 11:23:55 pm by Freakshow »
74 Yamaha YZ's - 75 Yamaha YZ's
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For sale -  PRE 75 Yamaha MX stuff, frame, motors and parts also some YAM DT1,2,A and Suzi TS bikes and stuff

Offline JC

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Re: Pre '75 legal ?
« Reply #11 on: July 11, 2008, 02:10:10 pm »
Mark,

I don't think it matters either, up or down, but as you know, I'm not a scrutineer. 125/175TNTs had up-pipes from the beginning.  Its hardly a performance issue/advantage - more a practical one. They also look much better w up-pipe in my view.

250TNTs hardly changed until 77 TNT when they also came w up-pipes.  TNTs kept w Al cases I believe whereas MXs went mag from MX2, so flow-on rule would unquestionably apply I would have tho't.

Works 250s in Gary Jones era had down-pipes as I recall, but Ellis's bikes soon had up-pipes.

I would have tho't that since 'snake-pipes' were available "aftermarket" in 74 they'd be allowable on any bike they could fit.

JC

Offline Canam370

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Re: Pre '75 legal ?
« Reply #12 on: July 11, 2008, 08:44:30 pm »
Hello people. Nice to see the Can Am troops coming out to play finally! From my own experiences with using Can Am's pre-'75 the rear suspension travel needs to be limited to 4". The engines are almost illegally quick and the back-end likes to come play with the front in the choppy stuff! Stay on the gas or else.... Can Am 250's ran only with a downpipe until '76. The 125's and 175's used an up-pipe.The MX-1 125 ran a high pipe but the 250 MX1 & 2 ran downpipes until '77 and the introduction of the MX3. If you are going to run a high pipe you will need to change the airbox, sidecover and shave a few head fins off. I own a few orange tankers as well as white tank models and they are a lot easier to own now that a/m gear is being made to keep them going.
  Yeah, I remember that Barrabool stouch withe Drakie....the bikes he ruled illegal had MX6 swingarms fitted with well over the travel limits.
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