Anyone seen this before?

[K2-K6]

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Found it in a recent 2011 bike mag,  never seen it before but interesting.

[SteveD CB500K0]

Water cooled?


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[JamesH]

2-stroke?

[K2-K6]

I had the advantage of seeing it within an article on rotary valves else I'd not have guessed.

Basically a special head with a big ported camshaft instead of valves to get gases in and out.

Used in Australian Greg Kensig's sidecar racer, I've never seen it before.

[MrDavo]

Looks all CB750 below the base gasket, I’m guessing there’s a sleeve spinning round with carefully timed passages to let gasses in and out, with no valves to tangle I’m guessing it will take more revs, and use less power, but surely you’d still need a camchain to keep it in time.

[K2-K6]

Yes,  as you've said,  a big sleeve effectively. Just thought it interesting as it's based on the Honda bottom end.

https://markwalkermotorcycles.com/motorcycles/big-ned/creating-big-ned/

Bit bigger scale on this link but same principle,  think they're both inspired by the same engineer named David Dunstan.

[K2-K6]

Found another odd one, twin cam this time

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http://www.curtisracingframes.com/articles/cycle-canada.html on this link for more details

[UK Pete]

Wow how interesting
There are some really clever people out there

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[Orcade-Ian]

Like many of us on here I make a lot of stuff in the workshop myself but these guys are leagues above a simple engineer and to carry out mods like those requires in depth knowledge of drawing, pattern making and metallurgy, let alone precision engineering.
I would take my hat off to them if it wasn’t so bloody cold and I had hair!
Many thanks for posting these links folks - these things will die out if successive governments insist on making any mods to road vehicles impossible.

Definition:  Engineer - a simple machine for transforming good metal into scrap.

[steff750]

Like many of us on here I make a lot of stuff in the workshop myself but these guys are leagues above a simple engineer and to carry out mods like those requires in depth knowledge of drawing, pattern making and metallurgy, let alone precision engineering.

 yes there are some very clever engineers out there .this reminds me when one of my mates wrecked the big ends on his honda goldwing this was in the 1970's and he could not afford to get new ones from honda ,anyway he took the old shells to a local engineer in swansea autos he matched them up with austin mini shells and all this was done off the top of his head and he wrote all the sizes  on a piece of paper lol happy days

  sorry for hijacking the thread guys. keep them photos coming

[Tomb]

My father had a Royal Enfield Crusader Sport with a worn crank big end on its last regrind, no more shells available, we went to the local crank grinders and asked if they had any shells 10 thou smaller, Austin Allegro were but the outside diameter was bigger so I bored out the conrod big end to fit the Allegro shells, they reground the crank and my father ran the Crusader for years like that. It was 28 years ago, he still has the Crusader.

Another mate had an XL185 with a cam that had eaten the head bearings, I bored the head out bigger, cylindrically ground the cam journals to clean them up, and made a phosphor bronze bush to fit, it was a floating bush with oil holes and scrolls for oil distribution, again ran for years like that and was sold running perfectly.

Not in the same league as the posted mods but when you're an engineer its bread and butter.

[K2-K6]

No problem with anything regarding engineering on here, I was just idly looking through stuff on a snowy day and thought it of interest.

As already said,  there's some very clever people around working on all sort of things. The last two examples show how much can be lost if education thinks of everything just has an academic focus without real practical elements to let people discover their own skills and the scope of what they can achieve.
I like going to things like the Goodwood festival of speed,  not just for the vehicles being run up the hill,  but just to spend the day in the paddock with such an extraordinarily diverse range of engineering. It never ceases to amaze me the quality of thinking in creating some of these things. I've seen some very clever solutions and engineering concepts there.
But also on this site,  the shear skill levels,  huge research, and dedication to look after and get things running I feel is inspiring.

[Bryanj]

In the big end vein the early 500 triumph twins had a white metalled steel cap and alloy rods, the crank pin being the same diameter as the later shelled sort we had the crank ground then bored the rods to fit shells, which cut into the bolts so put half roundish slots in the shells where the bolts were (new bolts of course) and spent hours filing small slots for the tangs on the shells--worked fine for many years considering it had the fancy alloy barrels and head

[K2-K6]

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Is this a real bike or model? Photo looks quite convincing,  but did it exist as prototype?

[hairygit]

Looks real enough, although the carbs look wrong.

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