Honda-SOHC
Other Stuff => Misc / Open => Topic started by: McCabe-Thiele (Ted) on December 14, 2025, 06:53:05 PM
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Obviously I've seen Police Rotary engined Nortons, a bike famously raced by local lad Ron Haslam.
Never knew Suzuki built one until I read on old issue may 2003 of m/cycle Mechanics. The main gripe was it's poor fuel consumption.
I've never seen one, has anyone here ridden or owned one?
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Never ridden one, they are very rare,
Very interesting instrument binacle,
The two exhaust had ducts in the downpipes to get cooling air,
In the early 70's, they were big,shiny and unusual
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Yes the Instrument binacle cover that rolls up when the ignition is switched on.
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The later model didn't have the rotary binnacle but made do with normal Suzuki clocks.
The RE5 very nearly bankrupted Suzuki after spending millions on a licence fee, the development costs followed by endless warranty claims due to excessive rotor tip wear and especially in the USA. It was so expensive to take the engine apart to replace the rotor tips Suzuki ended up replacing the whole motor as it was a cheaper (but still expensive option).
The bike was an absolute disaster for the company, heavy, unreliable, excessive heat and expensive to buy and run. I read that Suzuki recalled all the bikes left unsold and crushed them, they also did the same with any bikes with faulty engines giving the owners other models instead.
I know the original VF nearly bankrupted Honda but they had the corporate clout to ride the storm and take the engine back to the drawing board, Suzuki in the early 70’s when they were designing the RE5 were a small player.
Yamaha also dabled with a rotary but knew it was a dead end and didn't really pursue the idea.
The only company who made a rotary work was Norton but that was following years of development.
The Dutch VanVeen OCR was a lovely but expensive bike in the mid 70’s but that used (I think) a Citroen twin rotor engine that Citroen couldn't make work so VanVeen bought them up!
The Hercules (or DKW depending where you live) was a snowmobile engine and was actually the same engine design and capacity as used by Norton although Norton used a twin rotor configuration.
Even in the car world it was Mazda with the RX7 and RX8 who made the rotary work but even they have dumped the idea.
The rotary still remains a great engine and I'll never forget spectating at the Crag on the IOM hearing the wail of the JPS Norton's coming down from the mountain, what a sound.
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There was another firm made rotarys DK had oil mix and injection pnes, saw both at a wholesellers in London called Mobyke, both had been wrecked mechanically by the press notputting oil in!
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I was going to mention the Van Veen OCR too Dave :) didn't realise that was the Citröen derived motor though.
There was a Citröen GS prototype rotary lurking in the corner of a garage recently, I think it was on Drew Pritchard car program when he went to by a NSU RO80 ... the owner noted that it was an "escaped" development vehicle.
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Speaking of Mazda and their rotary development, along with the sound of a rotary on race pipes.
https://youtu.be/i8wX0V_mwG4?si=6vLaRO-jIk5PrKiE
One of the most spectacular rendition of their quad rotor competition engine that did win Le Mans 24hr race outright.
Up there with a Honda 250-6 for evocative mechanical creation.
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The ones i saw were DKW but known as Herculese everywhere except UK, aparently the Norton was derived from it and it was late 70's
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Impressive
That Mazda
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I was intrigued at the time when the Mazda RX7 was being announced. I couldn't afford it but wanted one.... what killed them was the horrible fuel economy. The RX7 had a 4 barrel carb on it. My sister had a Wankel powered snowmobile back then, I had moved away from home, but found it out behind Dad's shop rusting away. Later a boarder at my Dad's place late 2000's had two green RE5's sitting in the shop. He was saving them for "one day" getting them running. They had the rotary dash. I never was able to see them with power on. I was very interested in having those two bikes, but alas the gent wouldn't part with them.
The local Suzi/Honda dealer has a '76 RE5 .on the showroom floor asking nearly C$16 k for it. 1289 miles on it. Has the standard clocks.
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In 1973 I was working for an Audi/NSU dealership several years before the VW retailers merged.
The first NSU RO80 cars. Had a twin headlamp front end with a four plug rotor engine. The gearbox was a two pedal manual with a micro switch in the gear knob that operated the clutch.
Plug fouling and exceeding the revs would destroy the engine.
The later model had a more modern rectangular Headlamp. The engine was quite different being a two plug unit so only one plug per rotor. It also had a catalytic converter plus an electronic rev limiter. This later model was a huge improvement. Sadly the warranty costs on the early model was bankrupting NSU who were bought out by Audi who killed off the short lived later model.
They were great to drive, very quiet, very smooth engine once you mastered the gear shift, fuel economy was in the low 20 mpg region.
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Interesting account given here from within BL development https://www.aronline.co.uk/opinion/i-was-there/bl-rotary-engines/ but the comments section fascinating too, with personal account of racing an RE5 ! along with very well described limitations within the design.
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Interesting account given here from within BL development https://www.aronline.co.uk/opinion/i-was-there/bl-rotary-engines/ but the comments section fascinating too, with personal account of racing an RE5 ! along with very well described limitations within the design.
Thanks for that link
Fascinating
I noticed a 500 Honda finished in the places
4 or twin??
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Mazda are still at it. Twin rotor rotary hybrid + carbon capture.
Mazda’s done it again: the Vision X-Coupe is a 503bhp rotary-engined concept | Top Gear https://share.google/VXGVingbPbSg7Ew6A
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Interesting account given here from within BL development https://www.aronline.co.uk/opinion/i-was-there/bl-rotary-engines/ but the comments section fascinating too, with personal account of racing an RE5 ! along with very well described limitations within the design.
Thanks for that link
Fascinating
I noticed a 500 Honda finished in the places
4 or twin??
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I think you'd guess at a four being the choice, but you never know though.
The RE5 riders sound like quite capable characters by that account of riding around last laps on deflating tyre, which looked to have held sway over the nimble quality of a good 500 Four.
I remember watching an Australian proddy race in which the Yamaha XS 1100 were amusing in their competitiveness, given that they looked like elephants clomping around at high speed. A triumph of adventurous and advanced riding techniques if ever there was one.
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Mazda are still at it. Twin rotor rotary hybrid + carbon capture.
Mazda’s done it again: the Vision X-Coupe is a 503bhp rotary-engined concept | Top Gear https://share.google/VXGVingbPbSg7Ew6A
Nice looking concept Tim. I do like Mazda's and one of the only companies to continue with big block ICE's rather then relying on small 1 litre or less three cylinder engines with a turbo attached to give the same power with a lot less reliability.
Nigel, the sound of that race Mazda, absolute bliss and up there with the V6 Laverda👍
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Interesting about the rotary engines. There was even one found its way to the Orkney isles back in the day, not sure whatever came of it. There was quite a few R0 80’s around here as we had a local dealer.
Even although we were quite often asked if we Electricity! 😳😂🤣
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I was going to mention the Van Veen OCR too Dave :) didn't realise that was the Citröen derived motor though.
There was a Citröen GS prototype rotary lurking in the corner of a garage recently, I think it was on Drew Pritchard car program when he went to by a NSU RO80 ... the owner noted that it was an "escaped" development vehicle.
You couldn't guess it was a car engine Nigel, they fitted a number of fancy covers over the engine to disguise it's origin's. I remember seeing this bike in a weekly magazine called 'On Two Wheels' back in the mid 70’s when I was a young teenager.
Van Veen rose from the dead a few years ago and made a few more OCR's from spares laying around, they were of course, reassuringly expensive!
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My missus used to work for Mazda and I considered buying an RX8 until the workshop guys told me how much oil the engine used. Around a pint a week with my mileages back then. Oil ain’t cheap these days and its mpg was pretty low as well. I bought a Mazda 3 instead.
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Just looking at an image of the Van Veen. A bit nicer looking than the Suzuki but that ain't hard
I really struggle with the looks of bikes with more unusual engines than the normal 4 & 2 strokes we know. Don't want to be a luddite but he rotary and latterly electric motors just look bulky, heavy and clumsy to me. Or is it just me? 😳
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Mazda are still at it. Twin rotor rotary hybrid + carbon capture.
Mazda’s done it again: the Vision X-Coupe is a 503bhp rotary-engined concept | Top Gear https://share.google/VXGVingbPbSg7Ew6A
Nice looking concept Tim. I do like Mazda's and one of the only companies to continue with big block ICE's rather then relying on small 1 litre or less three cylinder engines with a turbo attached to give the same power with a lot less reliability.
Nigel, the sound of that race Mazda, absolute bliss and up there with the V6 Laverda👍
It would be fantastic if that V6 had got into more of a production run wouldn't it Dave :)
The rotary of course is a triple fire for each revolution of the trichiod component, geared to the crank though to give that equivalency calculation for its capacity.
All version and derivatives of the firing 3 just sound so good though, don't they.
That 767b Mazda effectively pulsing as a 24 cylinder four stroke with its 4 rotors at 3 pulses for every rotor revolution (two stroke cycles) to give that unearthly guttural howl :)
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Interesting about the rotary engines. There was even one found its way to the Orkney isles back in the day, not sure whatever came of it. There was quite a few R0 80’s around here as we had a local dealer.
Did they have that greeting German owners of NSU Ro 80's had when they encountered each other, where they would should three, four, five or whatever amount fingers to represent how many engines they have got through? :o
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Not sure about engines but there was at least 2 that required a bit of panel beating and maybe a few panels when they ended up in fields.😜 Ah, those country dances they were great!😂
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Don't know how true this is but my mate is a pretty straightforward no BS chap. In the late 70's he used to have Suzuki's delivered in the crates to his home workshop by Heron Suzuki to assemble for a dealer friend. The delivery guy dropped the crated bikes off for assembly but said he had a couple of crated RE5's on board that he was instructed to take for disposal. He said to my mate if he wanted to bung him a couple of hundred quid (can't remember the exact figure) he could take one no questions asked. My mate never took him up on it but kind of regretted it afterwards.
I remember a chap at work (not somebody I really knew well ... just saw him in the car park where I parked my 400/4) .... buying an RE5 and it quickly developed serious problems so he was loaned a GT750 Kettle, whilst it was away being fixed. Never saw that RE5 again and the guy always turned up on a GT750 so I guess he never got the RE5 back again, and did a deal on the GT750
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That’s interesting Ash, I read something about the CBX1000 prototypes too that were supposed to be disposed of, were they?? Can’t remember where I read it, maybe on here even.