"Major components" + pre-65 = what?

[Nathan S]

OK, so I'm intending to build a pre-65 bike out of a Yamaha YDS3 - its my first foray into the pre-pre-70 era, and easily my most stupid project yet....

Now, I've realised how little I know about this era.

1. I have a set of ex-Cooper, Mexican-made 35mm Betors. I believe that these are OK for pre-65 because they're copies of Cerianis (and are essentially carry-over parts). Yes/no?

2. What triple clamps should I be using? Are there any (relatively) readily available pre-75 or pre-78 clamps that are legal?

3. Brakes/hubs? I note the pre-70 Maico 350 article in the current issue of VMX recommends using a post-69 front hub/brake, and a lot of the pre-65 European bikes seem to use pre-75 type hubs. Is this actually OK? Or just something that people turn a blind eye to?

4. Carbs - I know nothing of the older stuff, and was planning on using a pair for round slide Mikunis from a pre-70 Yamaha. Is this OK?

Anything else I should know?

[albrid-3]

You can use, Hubs, bultaco full width, maico full width hub, montesa full width hubs, british hub, greeves, cz hubs, early yds2 and 3 hubs, jawa hubs.
triple clamps, bultaco. Husky,montesa, ossa. all 35 mm
Carbie, mikuni fine
Forks---Bultaco, montesa, ossa, Greeves leading link, Early Husqvarna fork the same as my Husqvarna.
Check the rule book.

[Bamford#69]

Hi
Just be careful , read as much as you can from magazines of that period ,  and check the rule book ,
read # 18.7.3 Tables of acceptable components
The reason people use CZ forks and hubs is because of the "CZ motorcross and pattern parts" wording,
and #18.6.04 re carbs, "any roundslide carb of a type available pre75.
Sorry I'm not familiar with Coopers Betors Ceriani, or Maicos.
They only turn a "blind eye" until you start beating someone .
Try Google;  Yamaha Ascot / Asama scrambler,
cheers  

[jimg1au]

nathan
we should talk i am building a pre 65 race bike as well.
forks are ok as long as they are the short slider style later models had longer bottoms
i am using ossa forks and alloy tripples
there is a list of wheels you can use on the ma web page
mikunis will be ok

[albrid-3]

its nice to hear that pre 65 bikes are still being built., Nathan send me some photo`s of your finished porject, the ascot scrambler

[firko]

 

I have a set of ex-Cooper, Mexican-made 35mm Betors. I believe that these are OK for pre-65 because they're copies of Cerianis (and are essentially carry-over parts). Yes/no?

Nathan the Cooper Betors are fine. I've got the same forks on my Ducati and Alan has them on Black Betty. They are indeed copies of Cerianis.

What triple clamps should I be using? Are there any (relatively) readily available pre-75 or pre-78 clamps that are legal?

Arces brand triples that come with Cerianis are the ticket but they're expensive. Betor clamps are almost as good and easier to find. Do you have the Cooper clamps to go with the forks? If so they're fine.

Brakes/hubs? I note the pre-70 Maico 350 article in the current issue of VMX recommends using a post-69 front hub/brake, and a lot of the pre-65 European bikes seem to use pre-75 type hubs. Is this actually OK? Or just something that people turn a blind eye to?

Seeing I wrote that Maico article perhaps I should admit that I've had a conical hub on my pre 70 Maico since 1974 and have never been knocked back in pre 70 vintage racing although Peter Lawson was rumbling about it at Coffs. I believe he would have protested if my bike had beat his. Theoretically I should be using a full width hub on my pre 70 but I guess it's a grey area. On your Yamaha are you using a 21" front wheel? If so go for a Bultaco full width,CZ,REH or Rickman. Easy and cheap on eBay.

Carbs - I know nothing of the older stuff, and was planning on using a pair for round slide Mikunis from a pre-70 Yamaha. Is this OK?

You should be right with Mikunis both flange or normal mount.

Anything else I should know?

The Yamaha twin is opening new doors so you're the pioneer here. I presume the problems will essentially revolve around knocking as much weight out of the bike without comprimising the strength of the frame. Getting it to handle motocross (I'm assuming you're planning an MXer?) will be a battle. Have you considered using another, more motocross friendly chassis with the Yamaha engine? If so consider the Sprite/American Eagle frame I've described in the Budget Bikes thread.
Greeves, Cotton or M11 Bultaco frames will also take the Yam engine but they're harder to find and more expensive.

[mx250]

I use to trial ride my YDS and I don't think the frame geometry will be a big issue. The Cooper etc triples will probably reduce the trail which will speed up the turning which will be a good thing.

Overengineering of the frame and engine lead to lots of 'difficult to remove' weight. Twin cylinder engines were rarely used for this reason. But there is opportunity, remove what you can.

Concentrate on the suspension and unsprung weight as you have suggested.

The other big issue will be ground clearance. Up pipes will be the answer. With up pipes and the width of the motor at the gearbox you will ride bow legged .

The good news is that the 305 has ideal mx power; all bottom end and mid range - and good strong ponies at that. In the spirit of the period and practicality/reliability I would stay close to the standard carbs and porting. Talk to Lozza, I'm sure he would be up for the challenge .

An interesting project. On a 'period friendly' track I can see it been good fun and running with other period bikes. I don't think it will steal too many trophies. If it does it will be more the rider then the bike .

[Brian Watson]

You can use the small front brake from a Husky and the rear wheel from a pre '75 Husky is no where near the same as a pre 65 wheel...I like your shade of grey Mark...you certainly should be using a full width front hub..Do you want one? ..I have one that has the Maico emblem cast into the backing plate..That should make you bike completley legal and keep the evil peepers away!!

[pancho]

sounds like a fun dirt tracker with potential.cheers wally.

[firko]

That should make you bike completley legal and keep the evil peepers away!!

I don't particularly care Brian. The old Maicos having a long overdue rest while my Cheney RT1 takes over for pre 70 work. I used to be a bit paranoid about having the wrong hub on the bike but nearly every pre 70 Maico I've ever seen or competed against had the conical hub so I figured that if it's alright for the majority, it's all right for old Firko. The bike has raced at nearly every Nationals on this side of the island including Coffs a couple of years ago and even the toughest of rule nazis have passed it. Probably because they know that the actual brakes are exactly the same. Lawson was considering protesting but I mentioned a certain disguised Maico hub he once had on his Metisse and he got a bit quieter. All that aside,  I'm interested in that hub Brian. PM me with the details and price. Perhaps you could bring it over to the Nats.

[Brian Watson]

Now Mark, I belive you do actually care ..and that is why your are "paranoid" ..the thought that " well... if everyone else is doing it , then why should I change"...that type of stance is why we all go into lengthy discussions about what is "correct'"..you know that your bike should have a full width hub...The front wheel I have over here is out of Dad's 1960 250...at the time there was another 250 here also and the front hub may well be larger in dia than a pre 70's front hub..I have just checked with Dad and the dia of the hub, flange to flange is 227mm...

[mx250]

Hey Nat, why don't you use an AT-1 hub/brake? You have one in your collection haven't you, 21 inch wheel and all. That hub dates back to at least the YG1 of 63.

It maybe a little marginal in braking power for the weight of the beast but that is offset by lightweight and superior suspension compliance. If you have one I would be trying it - it has the reputation as being the lightest and most powerful of the period. If you have one it should be easy to try. If it proves completely under powered whatcha lost?

I would be tempted to stick with the Yammy rear. It might be a little heavy but it is powerful - maybe too powerful in the dirt - but at least I would give it a go. At the very least swapping it should be a low priority. Start with the Yammy brake and steel rim and see how it goes.

[firko]

The front wheel I have over here is out of Dad's 1960 250

That'll work in well with my upcoming pre 65 Maico/Sprite project. I'm interested.

Now Mark, I belive you do actually care

Brian...What I actually meant was that I don't really care any more as that old bike is going into garage queen retirement. I'd rather keep her in the condition in which she raced rather than retrofit parts that were never a part of the bikes race history.

[firko]

I bow to your Knowledge Graeme but wouldn't a DT1 full width hub be a bit better on Nathans project? I've been told by cluier folks than me that the DT1 hub went back to the early sixties as well....I'm not sure if that's true but if it is it'd be a better choice than those pissy AT1 gizmos.

[Nathan S]

DT1 hubs sound like the ideal option.

Anyone got any more input on the pre-65 legality of these?

(And thanks for the input so far, blokes. I'll reply in more detail when I'm not about to go to bed. )