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.
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.
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
' 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'.
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.
acotrel wrote: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.
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.
Without reservation, I'd say that this bikes is probably the nicest that I have ever seen in my 55 years of involvement with motorcycles. I almost built a Seeley framed version back in 1978, however could not figure out how to do the head mount for that Mk3 Frame.