ATK406 class eligibility?

[bishboy]

Thanks to Firko I am now looking at the ATK406 frame, swingarm and seat on marks swapmeet.  The front end is is not in good nick so I won't bother with it.

I'm looking at frankenbike options. So I don't have to swap over shock and chain guard mounts, especially the shock mount on the frame, I'll probably use a 2 stroke Husky/KTM engine option.  Given the extra weight and complexity, I don't think I'll consider a 4 stroke option.

If I use an evo compliant front end (say YZ250/465) and air cooled engine, probably Husky/KTM 420/495/500, would there be a chance it could be an evo compliant bike given that the frame is not from an evo bike (believe it's a 91 model), even though it has a non linkage rear end?

Second option is to make a pre 85/90 bike, but again as the frame is a 91 model, would it be pre 85/90 compliant? 

The other way to go is to just build something cool, but still using parts all from the late 80's early 90's era.  Maybe some USD forks with billet triples, aftermarket swingarm and a water cooled KTM500 motor    Would just have to work out to mount the radiators    

Maybe I just build the first option and just have a bike to ride, may just come down to the dollars I want to throw at it.

[Rossvickicampbell]

if the frame is 91 it doesn't fit in anywhere?

[evo550]

Yep your buggered....unless no one cares
The early fourstroke's had drum brakes (around mid/late '84) that are evo legal.
You could argue the carry over rule between the '89 and '91 model, but I don't know enough about them to comment on differences.
Have you actually confirmed frame date?

[Nathan S]

Make sure it has a drum front and an air-cooled motor, then just enter it in Evo as a 2013 Bishy250 and you're sweet.

[firko]

I could be proven wrong but I believe that the 84 model was the only ATK with drum brakes but I think they only made the 560 4t, the 406 2t wasn't released until 1988...with discs, including the countershaft disc brake. I'm fairly certain a drum brake  retrofitted '91 406 would be stretching it a bit too far.....more's the pity as the ATK would otherwise fit right in and be a positive addition to the Evo class gene pool.

[evo550]

Your spot on Firko, and you see even fewer of them around that the disc braked '85 model.
Bishboy, there is a 89 406 frame and swingarm for sale in L.A. for $21...
http://losangeles.bidbut.com/a,54,646948,89-ATK-406-Frame-wSwing-arm-Tank-extra-Hardware-Clean-kick-stand-KTM----21-Southern-California.htm

[popeye]

Doesn't it say in the the rule book somewhere that if the bike doesn't differ from the model before it is allowed? Could be wrong but I'm sure I've reed this somewhere will Have to check up on it..

[crash n bern]

The only difference I can see in the pre 90 frames to the 91 frame is the early ones are blue and the 91 is nickel plated. So it might just come down to being whatever year you say it is.

You can buy rebuilt 406 motors for $1,795US.  I recently passed up a Rotax 250 engine out of a SWM for $140 minus piston and carb.  I'm still wondering where my head was at, at the time. But at least it ended up in a SWM rather than lying under my bench.



Lots of info here.

http://www.americandirtbike.com/

[firko]

This place is a good source for ATK/Rotax bits. They love 'em for flat track so rolling frames or bits and pieces often come up. www.vft.org

[evo550]

The only difference I can see in the pre 90 frames to the 91 frame is the early ones are blue and the 91 is nickel plated. So it might just come down to being whatever year you say it is.

You can buy rebuilt 406 motors for $1,795US.  I recently passed up a Rotax 250 engine out of a SWM for $140 minus piston and carb.  I'm still wondering where my head was at, at the time. But at least it ended up in a SWM rather than lying under my bench.



Lots of info here.

http://www.americandirtbike.com/

Here's a rebuilt 406 motor for $1500
http://www.americandirtbike.com/toppage11.htm
What better way to start off your 406 resto than to build one around a motor 

[bishboy]

I thought it might be a bit ambitious as an evo bike.  From my understanding the frame only had minor changes over the years. There are quite a few frames for sale in the US, but the nickel frame is very cool.

A pre 90 bike would be the logical option, but I'm not overly interested in putting the original engine in it.

Engine choices probably limited to air cooled euro engines, maybe even water cooled if can work out to mount them and find a tank/shroud combo that works.

[firko]

but I'm not overly interested in putting the original engine in it.

You'd be scratching to find a better air cooled 2 stroke than a 406 Rotax........and as an added bonus, they bolt right in there.

[evo550]

but I'm not overly interested in putting the original engine in it.

You'd be scratching to find a better air cooled 2 stroke than a 406 Rotax........and as an added bonus, they bolt right in there.

Again Firko's right.....the only reason Maico 490's are the cream of the crop in the evo class, is because the big bore rotax motors unfortunately ended up in shonky frames(Canned Ham).

[09.0]

I thought it might be a bit ambitious as an evo bike.  From my understanding the frame only had minor changes over the years. There are quite a few frames for sale in the US, but the nickel frame is very cool.

A pre 90 bike would be the logical option, but I'm not overly interested in putting the original engine in it.

Engine choices probably limited to air cooled euro engines, maybe even water cooled if can work out to mount them and find a tank/shroud combo that works.

To my way of thinking as well as the rule makers, it is ambitious to put a post '90 bike into pre '90