VMX scrutineering

[rough rider]

not sure what the story with this 125 is then , we were told it was the bike he used and my uncle bought it from bashem and we still have the numbere plates that were on the bike when he rode it in the nationals somewhere.  but it has 72 on the id plate unless the titles were in late 71 and he aready had the next years model ??

anyway back on topic 
are we able to use these plastic replica CZ coffin tanks in pre 75 shown in the link below , tried to find out in the gcrs but its  unclear

http://www.crhighperformance.com/pictures/tanks200.jpg

[GMC]

Yes.

You can change cosmetics, exhausts, handlebars, ignitions, carby's (so long as carby is a pre 75 model) guards, etc. etc.
You’r supposed to keep original...
frames, hubs, forks,
crankcases, barrel and head must be the same externally.

You can change pistons from any model but you supposed to keep the original gearbox.

You can also swap any part from any other model so long as its from the era that you’ve entered, eg, pre 75

[firko]

are we able to use these plastic replica CZ coffin tanks in pre 75

Absolutely. Everything GMC says. As long as all of the major parts used on the bike were available prior to 1975 or are replicas of pre '75 period parts you're fine. The plastic tank shown is a replica of commonly available aftermarket tanks from the period. (Pacifico, Clarke etc).

The exception to the above are....., ignition, fork internals, shock absorbers (no remote reservoirs), tyres, engine internals (as long as any capacity increases are acknowledged by entry in the class reflecting the new capacity). All of these items are classed as "consumables" that can be replaced with modern alternatives. As GMC says, the engine must remain externally unchanged but aftermarket heads (Webco, ACK etc)are allowed as long as they are period correct.

The VMX builders best friends are period magazines with articles and ads showing the aftermarket parts used as well as articles, tests and ads on the bike in question. The second best friends are the guys who have built similar bikes. As they've done the hard yards in the past, they'll surely have an inside line on build quirks, parts sources and potential pitfalls. The third best friend is the MoMs rule book which will help you with the basics. The book is far from perfect but it's difficult to build a bike correctly without it guiding you through the legalities.

[tony27]

If you're looking at getting a plastic tank it may pay to give Les at Vmx unlimited a call, I was talking to him last week & he reckoned tanks cost about $200. The site only has about 20% of the products he stocks on it at the moment

[rough rider]

well i have the 125 fully stripped down , had the frame sand blasted and resprayed and am starting to re assemble it while the engine is being rebored etc
just want to check , i want to ride this in the pre 75 125 class as it is or was purchased in 74 , although the id plate has no year stamped on it for some reason ,
i need to have the rear shocks rebuilt as they are leaking ,which were the air type shown here

http://ausvmx.ning.com/photo/cz-098?context=user

 before i spend any money on them i want to make sure i can use them in this class , other wise i will put the money into getting 2 new shockers which are ok to use
the center to center measurement is about 1/2 " longer than std shockers and the original mounts are still on the frame and they are the mounts i will be using
these shocks were purchased separatly to the bike , not sure if they were avalible before 75 ?

[SAABCOMBI]

you won`t have any problem if you use them, but it would be best to have a look around, NJB shock are very good 99 pounds. falcon shocks, hagon shocks, all worth considing. cheers 33 m

[090]

You are allowed to use 2011 shocks as they are a consumable. The only thing is you cant use a piggy back type (which they arent) and you cannot have more than 100mm rear wheel travel. So you put one shock in and take a measurement from the rear axle point to a static point on the rear of the frame with the shock extended and again when fully compressed. The difference can be no more than 100mm. Hope this helps.

[rough rider]

thanks guys

[GMC]

You are allowed to use 2011 shocks as they are a consumable.

I'm no authority on the issue, but I wonder if an airshock is okay for pre 75,
If airshocks were avaiable before 75 then it's not an issue.
It would be a bit like fitting a shortened Fox Shox to a pre 75.
You can use any shock that has the same / similar technology which is why you can't use piggybacks in pre 75, just wondering out loud if the same applies with these shocks???

[090]

Good point. Best ask 211Kawasaki to be sure about that one.

[oldfart]

CZ had a form of air shock fitted in 73- 74 on their works bikes and became a production item in 1975 .       

[LWC82PE]

There is heaps of info and pics on CZ’s here that may help you inc set up an tips of forks and those air shocks you have.

http://sports.groups.yahoo.com/group/cousinweedy/
http://sports.groups.yahoo.com/group/ZedandWeedysOtherPicturePlace/
http://sports.groups.yahoo.com/group/zedandweedy/

[Freakshow]

Who says you cant use piggy back in pre 75   what do you think thermo shocks are ??  or are you using a differing definition ?  Thermo piggies are standard on all YZ, MX and Dt from 1972'

[TM BILL]

happy to be corrected but i think as stewy says the production CZ air shocks were fitted to the 75 Falta models therefore inelidgible for pre 75 

[firko]

Piggyback shocks are totally legal for pre '75 but remote reservior aren't. We duked this old chestnut out at the Barrabool Nats many years ago when Roy Gay* turned up with piggyback Ohlins on his '74 Maico. I was called in to make a decision and allowed the bike to race based on the wording in the rulebook "remote reservior rear shocks are not eligible" doesn't say "piggyback". As Freaky has mentioned, a precedent has been set by Yamaha Thermalflows and more importantly, Marzocci piggybacks being available prior to 1975.

The CZ air shock is a situation that should be ajuducated by the commission but I feel that they probably should be allowed based on the wording in the rulebook as it stands at present. In other words, they pass every aspect of the listed criteria. Performance wise, they're nothing flash and I'd actually be looking for something a bit better if it was me building the bike.

* Has anyone noticed Roy Gay featuring in the TV ad for Real Insurance? As an actor he's up there with Pee Wee Herman for on screen charisma