Better than any Triton

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This bike would be excluded from racing against Manx Nortons and G50 Matchlesses under the rules of Australian historic racing. And I would ask the question WHY ? It is an extremely easy build and the motors are excellent and cheap.



 
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It is a four-valve Jawa that was not sold until the late 70s for one reason, is that good enough?

It did not exist in the 50s or 60s in the heyday of British racing singles.

The Weslake speedway engine, another four-valver did not appear until 1974, so it does not belong racing with British singles either.

The eso and jawa two valvers were around. all you have to do is document a historic case of someone using one in a Manx chassis in the 50s or 60s in road racing and present it to the sanctioning body.

IF the only criteria for historic racing was that they have to be easy and cheap then historic racing would not exist huh?
 
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I think the cheapest, most powerful engine of a single cylinder that would fit in a featherbed would be a Yamaha 660 engine. Tons of them around since they were used in the Raptor quad and various motorcycles. I have an MZ with that engine. 50 HP with mild tune, 80 HP with wild tune, and light.
 
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Is a Yamaha 660 engine, non-unit construction. If it isn't how would you get the weight distribution right ? In any case the capacity is silly, if it is over 500cc. - 500cc is about all the bottom end will ever reliably cop in a single cylinder motor
 
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' IF the only criteria for historic racing was that they have to be easy and cheap then historic racing would not exist huh?'

You cannot recreate history, and in any case 'historic racing' has become the only modern constructor's and development classes for the average punter.
Rudges and Indians had four valve heads way back in history.

Classic racing might be a much better option than 'historic racing' ? - Specify the classes based on technology and capacity - rather than date of manufacture and bullshit about what 'could have existed in the era'.
 
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Way back in the 1980s in the clubmans class racing there was a single cylinder racing 500 class, which was fine except all kinds of bikes came to the fore, Hagon Hondas, and even 2 stroke 500 from the moto -cross bikes- they started to blow everyone away.
If you had an old British 500 single it was no class for you any more, as the more modern bikes came to the track costing half the price new, to a secondhand Norton Manx.
Sadly that is the way it went until the Classic racing club became more popular.
 
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acotrel said:
This bike would be excluded from racing against Manx Nortons and G50 Matchlesses under the rules of Australian historic racing. And I would ask the question WHY ? It is an extremely easy build and the motors are excellent and cheap.



Is the bike in Australia?
 

Chris

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Hi

If you do a search you will find that Eso engined Manx Nortons dominated Classic racing in Australia though the 1980's

Chris
 
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We never used the Jawa four valve motors in Australian historic racing and there must be thousands of them laying around in Europe. Seems a shame not to use something so good, yet so cheap. To be honest I'd love to be racing a Molnar Manx or Walmsley G5 in Period 3 historic racing, however it is sheer idiocy to spend that sort of money simply for what is essentially appearance. I never get paranoid about being beaten in a race, however I get really irritated when there are major differences in technology or capacity. The worst thing that ever happened in racing was when two stroke bikes were allowed onto the same grid as four stroke machines. If that had never happened there would today be classes for featherbed framed four valve Jawa engined bikes. A four valve motor typically give a 10% performance advantage over a two valve equivalent. It is really no big deal to race them together in the same classes.
 
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This is what is currently being raced in our Historic Period 3. It almost gets there - however not quite :

 
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The motor is too far back. A Ducati motor fitted with two SOHC 4 valve Jawa top ends would make more sense.
 
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acotrel said:
The motor is too far back..
Its a drag racer - weight distro doesn't make much difference.
If the front lifts, they fit wheelie bars.

acotrel said:
A Ducati motor fitted with two SOHC 4 valve Jawa top ends would make more sense.
Why start with something expensive, and then have to remake all of it anyway....
 
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I think it might be cheaper to buy a 650cc Pantah and fit the Jawa barrels than make and machine crankcases for a V twin.
 
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acotrel said:
I think it might be cheaper to buy a 650cc Pantah
On what basis ?
You have previous experience with this... ???

Thats just a Weslake v-twin, so cobbling up something from something unsuitable to begin with sounds like trying to re-invent the wheel ....

 
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The bottom end from a Japanese V twin might even have a strong 6 speed box attached.
 
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Wasn't a magnum a V4 - in varying capacities.
And what year of Triumph. ?

Someone may have saved his life, depending on what combination we are talking about !?!
 
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