Tiger Cub Square barrel eligibility

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TriCub
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Tiger Cub Square barrel eligibility

Postby TriCub » Sun May 30, 2010 10:07 pm

I was just wondering if the eligibilty of the square head and barrel's for the Tiger Cubs could be verified as I was thinking of tracking a pair down for my Cub. The extra fin area would make a big difference to the hot running issues that the cub's have.
I found a page at this link below to "The Tiger Cub Bible" and in it ,it states that the oval heads remained until Feburary 1965. Wouldn't that mean that the Square head was only for the 1965 model bikes and later making it ineligible for pre65 ?
I hope someone can clear this up as it would be a big help in the smooth running of a Cub.

http://books.google.com.au/books?id=kgw ... &q&f=false



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Re: Tiger Cub Square barrel eligibility

Postby David Lahey » Mon May 31, 2010 10:01 pm

I read in the Supp Regs for the Aussie Titles that there will be an Eligibility Scrutineer for deterrmining Classic and Twinshock bike eligibility.

I hope that whoever is going to be that Scrutineer knows what they are getting themselves into and has the combination of the wisdom of Solomon and the patience of a saint.

I know that before the Vintage MX Aussie Titles there are internet forum discussions in the months leading up to the event between riders and the appointed Eligibility Scrutineer, so that all possible controversial interpretations can be sorted out well before any bikes are entered for the event. The person they usually have in this role is very highly regarded by the VMX community (and is a rider) and the process seems to work well at lowering stress levels all around.

Perhaps whoever is going to be the Eligibility Scrutineer for us at the Aussie Trials titles could have some sort of system so that people can get answers to their own particular questions well before the event?

I for one am very interested in the interpretation of the requirement for Twinshock class to only have carburettors designed before 1986. One of my Yamaha Twinshock bikes has a modern Mikuni VM26 (same carby as what came on Beta Rev3 from 2000 to 2008). It does look similar to the Mikuni VM26 carby that came on my 1976 Kawasaki KT250, but is that enough to get my Yamaha into the Aussie Titles?


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Re: Tiger Cub Square barrel eligibility

Postby paulm » Tue Jun 01, 2010 5:38 pm

You make a good point David.

As the owner of the Bike that won last year's Twinshock Title (ridden magnificently by Toby Coleman) I can tell you categorically that it is absolutely bog standard...

Well... apart from the side pull twist grip and gas filled Falcons – neither of which were available in the mid 80's to my knowledege and could make the bike ineligible under strict interpretation of 'rules'

And it's about to grow an OKO flat slide carb - clearly an abosolute no no... I'm glad it's not competing this year.

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Re: Tiger Cub Square barrel eligibility

Postby TriCub » Tue Jun 01, 2010 6:30 pm

David.
I think the wording of the rules saying any Carby designed before 86 would let in just about any carby. The design of all the round slide Mikuni's hasn't changed from the early 60's when they were made under licence to Amal.
They have the same number of jets and adjustments that have been there all along. The external appearance has changed and the material that they have been made out off has changed but from a design piont of veiw they are still the same.

By the way has this got anything to do with Tiger Cub barrel eligibility?



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Re: Tiger Cub Square barrel eligibility

Postby David Lahey » Tue Jun 01, 2010 6:48 pm

TriCub wrote:By the way has this got anything to do with Tiger Cub barrel eligibility?

errrrr.... sorry about that - but it is about eligibility


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Re: Tiger Cub Square barrel eligibility

Postby TriCub » Tue Jun 01, 2010 10:50 pm

David

I guess it is about eligibility. So I'll have another go.

I have been doing a bit of research on the history of various carbies and found some quite interesting facts.

1- Mk1 concentrics were not made until 1966 and not fitted to Tiger Cub's until 1966.
2- All early Mikuni's(there those nasty Jap Carbs) where made under licence to Amal and actualy had Amal on one side and Mikuni on the other.
3- I have seen a 1964 Yamaha 125 shop manual that has a brake down picture of the Mikuni made Amal and the technical asspect of it's design is identical to the round slide Mikuni's that can still be bought new today.

My question is why are we being told that we have to send to England and spend hundreds of dollars to buy a Mk1 concentric that clearly is not age eligible when we can pick up a round slide Jap carb that was designed before 1965 by the pomms anyway for a couple of dollars from the wreckers?
I'm completely baffeled by this Anal or should that be Amal ruling for the Aussy Title.

I propose that any round slide carb be allowed for Classics due to the fact that the technical aspects of the carbs hasn't changed since the mid 60's. They all have the same adjustments from idle screw through to main jet and it would make any eligibility a piece of cake, if it has a round slide it's ok!!!!!
The Mk1 Amal people are telling my that they can get them to work just as well as anything so what are they scared of???
This is how the rules is for Pre 65 motocross in Australia and it works very well. Beleive it or not on an MX machine quite often when a European carb is replaced by a Jap carb the power actualy goes down. So the main advantage is not performance but less maintenance.



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Re: Tiger Cub Square barrel eligibility

Postby TriCub » Wed Jun 02, 2010 5:28 pm

I just had a chat with the eligability expert for the Aussy title and he is of the opinion that the Square head and barrel are not eligible for pre 65 and won't be allowed.

It seem's that TwinShock from this forum with his 64 square barrelled Cub could have a problem with his bike thrown into the same category as the M10 Bultaco!!

I don't think I'll buy a square barrell and head for my bike just yet.



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Re: Tiger Cub Square barrel eligibility

Postby Twinshock » Thu Jun 03, 2010 8:52 pm

As you said previously George, the extra finning on a square barrel will help cooling and that is the reason I have one on my Cub.
I've been competing at all levels in trials for 50 years now and have ridden the waves of change many times in a couple of countries and you can put money on the fact that I will be at Thunderbird Park on my genuine and original 64' Tiger Cub in August, in Classic class and I look forward to seeing you and all the others there as well.
Cheers
Rog


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Re: Tiger Cub Square barrel eligibility

Postby TriCub » Thu Jun 03, 2010 10:34 pm

Good luck with your entry.
However I will not be competing as the organisers of the title have taken it upon themselves to rewrite the rule book and make my bike ineligible. I could do a carb change but I do not have the time or the money to source a Mk1 concentric before the event and get it fitted and tuned.



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Re: Tiger Cub Square barrel eligibility

Postby Twinshock » Fri Jun 04, 2010 11:47 am

Great news for square barrelled Cub owners with Mike Reilly's (Eligibility Scrutineer for Aussie titles) research revealing that square cylinder barrells and heads were fitted to a large batch of production Cubs in 1964, this is documented and factual.
Thanks for your diligent work Mike and for letting us know with some time to spare.
As far as I know there are only two square barrelled trials Cubs in Aus but if there are others that I'm not aware of lets have a line up, photo's and a beer at Thunderbird Park in August.
I can get back to my other projects now,,,,,,,,got to put a tube in my back tyre, and put the steel rims back on !!!.
Twinshock




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