Vintage nats allowable bike mods

[35elsinore]

Just wondering if any one can shed some light on whether a alloy swing arm on a 74 cr125 is allowed. Mine is rusted out am are finding very hard to locate another good one, yet a new alloy swing arm is available with shocker mount in original position. I cant find anything in the GCR's about swing arms and dont consider it to be the frame. Hope to hear from anyone involved in scrutineering for these gems at national level.
Thanks

[JohnnyO]

No they're not legal for pre '75 as they weren't available back in the day.

[35elsinore]

Thanks for your quick reply, not what I was hoping to hear. I understand DG, FMF etc aftermarket heads are OK to use but dont believe they were available pre75 either and are obviously performance enhancing in keeping the engine temp down. I guess that over time some things get excepted as the norm but lines have to be drawn. If anyone has a good 74 cr125 swing for sale it would be appreciated so as this old gem doesnt have to stay in the shed for the nats.

[Iain Cameron]

35 Elsinore yes dg had cr 125 & 250 chromoly s/arm only in 74 but a company called Boyd and Stellings where making alloy swing arms from 1972 for Yamaha so check out old mags

[Iain Cameron]

also check out a thread called "aftermarket parts in pre 75 "

[Gippslander]

This was running at the Nats last year -- I think it's called "precedent" 

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[LWC82PE]

Check this out to get an idea what was available back then

http://www.vintagefactory.com/vintage_aftermarket_mx_catalogs.htm

http://ozvmx.com/community/index.php?topic=15666.0

[35elsinore]

thanks for the links, it makes very interesting reading. One thing that doesnt get mentioned is that at some stage the old gear is no longer obtainable [eg bent, rusted, people not willing to part with] and thus stopping bikes from getting out the shed and bums on seats. If alloy swingarms were available on any bike in its respective class and parts are still made to replace unusable and unobtainable then for the future of our sport may need to be a bit more leaneant. I know lines need to be drawn also as the ultra competetive people we are always wants to stretch the boundries for any advantage. I love nothing more than seeing a concourse bike but believe a race bike is another thnig altogether. Hope this doesnt open a can of worms  as it is only my opinion and as we know everyones is differant.

[firko]

No they're not legal for pre '75 as they weren't available back in the day

Boyd and Stellings made swingarms for Elsinores and actually started doing them for other bikes in 1969. They were pretty crap though. That husky got a lot of attention at Conondale Nats too.

[JohnnyO]

No they're not legal for pre '75 as they weren't available back in the day

Boyd and Stellings made swingarms for Elsinores and actually started doing them for other bikes in 1969. They were pretty crap though. That husky got a lot of attention at Conondale Nats too.

I've never seed a Boyd & Stellings swingarm on an Elsinore, not even a photo in a '74 magazine and there are no alloy swingarms advertised for Elsinores in any '74 Motocross Action mags so i guess that says something.

[Davey Crocket]

This is my whole point with Cheapracer, if he wants to do good with helping get more bikes back on the tracks, then this is exactly what type of product he should be making.....alot of swingarms where modified back in the day and some done very poorly, your not the only one with this problem....RM250/370's rust out frames and swingarms quite badly...the list goes on.....why make a frame kit that is already taken care of?. You have the option of bidding on evilpay but sometimes the prices go through the roof and this is the cheapest form of motorsport to be involved in so alot of racers are on a tight budget....maybe we should start another post   "What parts do you need replicated" and then he could get a jist of whats needed?

[holeshot buddy]

paint it black

[TM BILL]

thanks for the links, it makes very interesting reading. One thing that doesnt get mentioned is that at some stage the old gear is no longer obtainable [eg bent, rusted, people not willing to part with] and thus stopping bikes from getting out the shed and bums on seats. If alloy swingarms were available on any bike in its respective class and parts are still made to replace unusable and unobtainable then for the future of our sport may need to be a bit more leaneant. I know lines need to be drawn also as the ultra competetive people we are always wants to stretch the boundries for any advantage. I love nothing more than seeing a concourse bike but believe a race bike is another thnig altogether. Hope this doesnt open a can of worms  as it is only my opinion and as we know everyones is differant.

As your not interested in a competitive advantage , i will happily straight swap your alloy arm for a straight std item 

If you believe your post has merit , lobby MA for a change in the rule book. I  think there are still plenty of swinging arms frames etc on ebay so a replacment shouldn't be to hard to find if you dont want to accept my offer 

[35elsinore]

TM Bill, I dont have an alloy swingarm, I started this subject to see if it was an option. Happy to buy yours though. GMC is an option I didnt think of, although Geoff is a busy man with a waiting list for frames etc. The alloy unit is an off the shelf thing, just seems a lot easier for no performance advantage.