Honda-SOHC
Other Stuff => Misc / Open => Topic started by: K2-K6 on March 01, 2018, 07:24:37 PM
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Found it in a recent 2011 bike mag, never seen it before but interesting.
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Water cooled?
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2-stroke?
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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.
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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.
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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.
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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
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Wow how interesting
There are some really clever people out there
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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.
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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
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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.
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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.
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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
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Is this a real bike or model? Photo looks quite convincing, but did it exist as prototype?
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Looks real enough, although the carbs look wrong.
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Along with the carbs, sidepanels come forward over where airbox is normally plus look at the odd shape of the generator cover.
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I have seen this on the sandcast forum I am sure it was a prototype
When it was going to be named the 750 dream or something like that
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Possibly the Kawasaki equivalent, supposedly a styling prototype.
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And the Yamaha too.
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Ahh, the 750 kwack prototype! They were apparently ready to show the world, but Honda beat them to marketing the first 4cyl 750 bike. They allegedly went back and designed the Z900 to get ahead in the race.
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Ahh, the 750 kwack prototype! They were apparently ready to show the world, but Honda beat them to marketing the first 4cyl 750 bike. They allegedly went back and designed the Z900 to get ahead in the race.
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You can see Z1R in that kwack prototype so not all wasted.
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(Attachment Link)
And the Yamaha too.
....Water cooled too???
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Ahh, the 750 kwack prototype! They were apparently ready to show the world, but Honda beat them to marketing the first 4cyl 750 bike. They allegedly went back and designed the Z900 to get ahead in the race.
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You can see Z1R in that kwack prototype so not all wasted.
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I didn't think of that one Roy, but it does look uncannily like the Z1R. As well as the tank those side panels and even front mudguard could be almost the same items for the shape and design concept.
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The Yamaha was ready to roll into production it seems, shame we never saw it out to customers.
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This kawasaki two stroke also seem close to the same point in development terms, although a square four appears to limit development.
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Regarding the Yamaha, being a 4cyl two stroke, that would have been and amazingly smooth running motor, but then again, fuel consumption would be scary, and with that tiny tank, a range of 30 miles ridden hard!!!!!!!!
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Ahh, the 750 kwack prototype! They were apparently ready to show the world, but Honda beat them to marketing the first 4cyl 750 bike. They allegedly went back and designed the Z900 to get ahead in the race.
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You can see Z1R in that kwack prototype so not all wasted.
The engine in the kwack looks like a virtual rip off of an MV Agusta 750. Nothing like what they ended up with?
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Those yam, kwak prototypes are a bunch if ugly dated buggers compared to the timeless classic good looks of the CB....
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Which goes to prove that beauty is in the eye of the beholder.
Its already been said, the Kwak has the clear lines of that timeless classic the Z1R which could never be described as dated, and the Yamaha prototype has the look of the beautifully lines of the XS650.
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Which goes to prove that beauty is in the eye of the beholder.
Its already been said, the Kwak has the clear lines of that timeless classic the Z1R which could never be described as dated, and the Yamaha prototype has the look of the beautifully lines of the XS650.
Or in the eyes of the beer holder.
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It's funny Roy that the MV was also considered a straight rip off from the Gilera racers.
The Kawasaki four stroke is interesting as it says it was a styling exercise done in Calafornia and would have been prior to the Honda 750 being revealed. As such the only general four cylinder bike engines readily viewable (other than Honda racers) i would guess would be the Italian stuff to style it around.
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Ray gun silencers on the Kawasaki, I wonder which bike those were first used on as a styling exercise.....
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Did someone mention xs650 Yam?
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I like the style!
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It was an era of fabulously exhaust pipes though. Honda did the right thing by going four separate route, I think it made that 750 really special and defined the whole period.
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Says it all really.
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Raygun silencers, not my idea of style but someones no doubt.
(http://www.classic-british-motorcycles.com/images/69BSA-Rkt3-L.jpg)
Talking of copying, Massimo Laverda openly credited the Honda CB72/77 as the inspiration behind the SFC engines.
(https://opimedia.azureedge.net/-/media/images/mcc/editorial/articles/magazine-articles/2011/11-01/1974-laverda-750-sfc/laverda-750-sfc-10.jpg)
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The Laverda looks like they've just scaled up with one of those parallelogram drawing frames :)
Just realised that Honda 750 picture earlier also appears in this magazine below
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Same side panels, carbs and also has a steering damper plus that straight orientation of the front brake master cylinder. Dated January 1969 it must of been photographed sometime around end of November 1968. Perhaps an early example to show and clinic to trade prior to production timeline, earlier than Brighton type example?
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Just looked it up and the bike in pic 1 is the prototype
Pic 2 is preproduction model
I borrowed the pics from sandcast forum(https://uploads.tapatalk-cdn.com/20180510/d3bd9fb9c5a2e9246be3c70ad51641a6.jpg)(https://uploads.tapatalk-cdn.com/20180510/fca22c97b18f00f84215f8654ddc2aff.jpg)
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Notice the drum front on prototype
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You can see the link from that black and white photo Pete to the colour pictures regarding the different shape alternator casting around the back edge, stater motor drive area.
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Honda 750 Four Special Speedway Edition? That's got to be a bit scary.
Very interesting prototype picture not seen that before. Ugly cam cover and seamless silencers?
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I think many cb 450 parts were used on prototype ..i may be totally wrong
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That early one appears in this site which gives it a background other than studio shot.
http://world.honda.com/history/challenge/1969cb750four/page03.html
Other interesting bits of information on other pages too.