ElectricMotorcycleForum.com
General Category => General Discussion => Topic started by: flynnstig82r on July 26, 2025, 11:42:17 PM
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Lately I’ve been reading up on ultra-high MPG carburetors from yester-year and trying to sift through the BS and understand the basics of how they worked. What I took away is that they were either too mechanically complicated for mass production (Smokey Yunick’s turbocharged evolution of Charles Pugle’s carburetor), or they made very little power and could only rev at a snail’s pace (Tom Ogle’s gas vapor engine). Ogle’s method should be the most-efficient possible, as the engine vacuum naturally pulls in exactly the amount of vapor that it needs, more precisely than any computer or fuel injection system ever could, but you won’t be able to get up to speed in traffic without some additional thought put into the drivetrain.*
My idea is to use a CVT to maximize torque to the wheel and combine with an electric motor. You keep the engine at its most-efficient RPM, even when idling, using a centrifugal clutch and variator like a scooter. You’d still have snailpig acceleration on the ICE alone, but enough power to hold cruising speed with astounding efficiency (Ogle got 100 MPG out of a big heavy V8 on a 55 MPH road, so a motorcycle could probably do even better). To achieve useful acceleration, you could use a small, powerful electric motor with a small, high discharge battery or capacitor system. Your gas mileage would be so high that you don’t any significant all-electric range, so you can keep the battery small and light (needs to be capable of high amps, though). ~5 miles all-electric range should be enough, basically an e-bike battery. The electric motor wouldn’t assist at all when cruising, only providing acceleration. A ~50 horsepower axial-flux or similar motor should be enough, and the gas motor continually keeps the battery topped up to 80%.** You’d end up with something on the order of 200 to 400 MPG in a motorcycle or maxi-scooter (potentially even higher with aerodynamic slip-streaming) and still have useful acceleration, thanks to the electric motor. If you like, you can substitute a Stirling motor instead of the gas vapor one, and the concept is the same. The Stirling wouldn’t need 100% gasoline and could run on pretty much anything flammable, among other benefits.
Why has no one tried to make a vehicle like this, when every other harebrained concept has been tried at least once? It would probably be easier to design a car on this principle than a motorbike, but I don’t think there’s been a car like that, either. It should be a lot cheaper and more sustainable to manufacture than a battery EV or plug-in hybrid thanks to the small battery, would pass any emissions test with no catalytic converter or other specialty equipment necessary, and should find its niche of buyers who would want ultra-high MPG. There must be something wrong with the concept that I’m not seeing for no one to have attempted it. Maybe those “big oil hitmen” have been really busy… ;)
What do you guys think? Am I chasing a fever dream, or could this actually work?
*It also requires routing the vapor through the airbox to avoid sucking in contaminants and a flashback arrestor so a spark can’t travel through the fuel line and make the whole thing go boom. You also need to get your hands on 100% gasoline with no additives or ethanol.
**You’d eventually deplete it with repeated pulls, of course. This would not work for long, spirited riding sessions without a much bigger battery and with no place to put it. This is just for normal city and highway riding.
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Look at the power system in use in Formula one today. That is in many ways similar to what you have described. Maybe studying that would give you some ideas on how to design your system. One of the most clever thing about the F1 system, IMHO, is the electrical systems connected to the turbo that are used to increase boost at low RPM. (Addition of turbo to your system could open up lot of possibilities.)
Maybe you are overcomplicating things?
How heavy will your system be? Extra weight will increase fuel usage and tire wear. If you'd concentrate instead on lightening and streamlining your bike, plus low rolling resistance tires, you could get amazing mileage. SuperCub can get over 100 mpg. Streamlining it and changing gearing should allow you to get close 200 mpg with a simple system for little money.
If you only use electric motor to accelerate from low speed you don't need to worry about gearing it for higher speed.
Regular electrical motors can be astonishingly powerful and efficient with a simple controller. Max efficiency is usually limited to a narrow RPM range. In the RPM range they are most powerful in they are usually not very efficient. With more complicated controller, and design of motor, you can use all sorts of winding trickery and computer controlled independent winding powering to widen the RPM range and play around with power and efficiency. Sort of like a digital gearbox. You'd need to be an electrical engineer and engineer to design a good system. Or ask AI to do it for you. ;D
Look into supercapacitors for power storage.
Headwind and hills can temporarily require more power.
Personally I'm not a fan of Axial motors. They have their uses but there is a lot of misleading information out there about them.
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Not a fan of the idea tbh ... I think all efforts should go into getting the range of BEVs up and the charging times and weight down, instead of creating monsters with two entire powertrains in them that still emit fumes.
And honestly I think we're actually quite close already, the tech now exists, just nobody's put it together in a bike yet. It should be entirely possible to get a 30kWh battery into a road bike and 4C charging with what's currently out there (there are batteries now in production that hold 500wH/kg). Of all manufacturers, LiveWire showed the obvious way to package batteries is to make them structural load-bearing parts and eliminate the space and weight of a frame.
To my mind ... 30kWh and 4C charging is entirely on a par with ICE in terms of usability. Why bother with crazy hybrid ideas?
Cas :)
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Look at the power system in use in Formula one today. That is in many ways similar to what you have described. Maybe studying that would give you some ideas on how to design your system. One of the most clever thing about the F1 system, IMHO, is the electrical systems connected to the turbo that are used to increase boost at low RPM. (Addition of turbo to your system could open up lot of possibilities.)
Maybe you are overcomplicating things?
How heavy will your system be? Extra weight will increase fuel usage and tire wear. If you'd concentrate instead on lightening and streamlining your bike, plus low rolling resistance tires, you could get amazing mileage. SuperCub can get over 100 mpg. Streamlining it and changing gearing should allow you to get close 200 mpg with a simple system for little money.
True, I believe Alan Smith achieved over 200 MPG with his Vetter-streamlined Ninja 250. I don’t know how to solve the crosswinds problem with streamlined fairings, though.
I’m hoping to shoe-horn a useful battery into the same space that a normal 12v battery would fit and then find somewhere to shove the electric motor (that’s the hard part and why I want something ultra-compact for its power). A hub motor would solve the space issue, but off-the-shelf hub motors are bad solutions for highway-capable bikes.
If you only use electric motor to accelerate from low speed you don't need to worry about gearing it for higher speed.
Regular electrical motors can be astonishingly powerful and efficient with a simple controller. Max efficiency is usually limited to a narrow RPM range. In the RPM range they are most powerful in they are usually not very efficient. With more complicated controller, and design of motor, you can use all sorts of winding trickery and computer controlled independent winding powering to widen the RPM range and play around with power and efficiency. Sort of like a digital gearbox. You'd need to be an electrical engineer and engineer to design a good system. Or ask AI to do it for you. ;D
Look into supercapacitors for power storage.
Headwind and hills can temporarily require more power.
Personally I'm not a fan of Axial motors. They have their uses but there is a lot of misleading information out there about them.
Interesting, what’s the downside of axial motors? I guess I’ve only been exposed to the marketing side.
I don’t know if I’ll ever actually take on a proejct like this, and probably wouldn’t have the technical chops even if I did. I was mainly curious to know why no one has tried it. I assumed there was a big flaw with the concept, but it sounds like it’s just an unexplored niche.
Not a fan of the idea tbh ... I think all efforts should go into getting the range of BEVs up and the charging times and weight down, instead of creating monsters with two entire powertrains in them that still emit fumes.
And honestly I think we're actually quite close already, the tech now exists, just nobody's put it together in a bike yet. It should be entirely possible to get a 30kWh battery into a road bike and 4C charging with what's currently out there (there are batteries now in production that hold 500wH/kg). Of all manufacturers, LiveWire showed the obvious way to package batteries is to make them structural load-bearing parts and eliminate the space and weight of a frame.
To my mind ... 30kWh and 4C charging is entirely on a par with ICE in terms of usability. Why bother with crazy hybrid ideas?
Cas :)
I knew you wouldn’t be a fan, Cas. ;)
The advantage to something like this is you can potentially convert an existing bike that would otherwise go to scrap, like those 80s Goldwing competitors from Suzuki/Kawasaki/Yamaha. Or if it’s a clean-sheet design, then you avoid all of the manufacturing emissions, cost, and weight of a big battery. It’s my attempt to envision a way to combine the energy density and low cost of ICE with the sustainability and electric acceleration of an EM using off-the-shelf components. I also just think it would be cool to get 200 to 400 MPG and ultra-low emissions out of a big, old, clunky motor. Then you can streamline it and maybe get a thousand :o
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hmm actually there is some merit in doing up an old clonker but I am thinking, what about EV conversion kits? Quite a few car kits are available but I've not seen much going on with bikes. A GL1500 with an electric powertrain... nobody would even notice the weight...
Cas :)
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hmm actually there is some merit in doing up an old clonker but I am thinking, what about EV conversion kits? Quite a few car kits are available but I've not seen much going on with bikes. A GL1500 with an electric powertrain... nobody would even notice the weight...
Cas :)
BTW, I saw a YouTube thumbnail yesterday with a title that said Gold Wing production was ending. To tell you the truth, I thought it already had, at least until I saw a new one parked at Alice's restaurant on Sunday. Boy, that thing sure had a lot of buttons to push. I bet its owner's manual must be really long. ;) Anyway, I agree that an old Gold Wing chassis would make a good platform to convert to electric power, but if you are going to do that, you might as well convert a small car, or maybe a trike, if you really wanted a lack of weather protection. You could stuff the batteries in the trunk. ;)
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An old Goldwing or similar would be ideal vehicle to convert to electric. I don't understand why no manufacturer has made a limited edition of that. Replace the boxer engine with a 30-40 kW watercooled batterypack and fast charge. Put 100 kW watercooled motor in there. It would probably weigh less than the regular Goldwing. :)
The reason small electric helper motors have not been put in a bike are probably weight, complexity and cost. Kawasaki made hybrid bike and it didn't sell well. Heavy, and it somehow got worse mileage than similar non-hybrid.
Some of the current negatives of Axial (or pancake) motors are cost, cooling, manufacturing complexity (requires precise alignment, flatness), control of magnetic flux and eddy currents (over-saturation and under-saturation), less standardization, limited supply chain and industrial know-how, torque ripples, structural stress and speed limitations, flat rotors prone to deformation, the flat/pancake shape not fitting in all spaces.
Some of these can be overcome with relatively minor changes, but except for some outlying cases the more standardized motor designs are usually a better fit.
Oh, is that all? ;D Well, so much for axial flux! I guess the Experia’s mini-EMCE is about as compact as you can hope for and still have middleweight power.
Btw, I looked a little deeper into it, and the reduction in power from a pure gas vapor setup might be a lot steeper than I thought. We’re talking like ~20 HP out of a 350 small block V8, so even a big motorcycle engine might not make enough power to be useful as a generator or maintaining a cruising speed. Seems like you’d be better off just increasing fuel atomization and restricting airflow, but that also robs power and you’re not getting 100 MPG out of a V8, more like 35-40 at 55 MPH. I knew there had to be a good reason no one has tried this approach: It just doesn’t pencil out when you need to make it perform on real roads. Oh well! I guess a person could do something like that with a Boss Hoss and make it get something like 50 MPG, or you could just ride a NC750X that already gets 65+.
Re: Goldwing electrification, I’ve thought about that more than a few times. It reminds me of the early electric cars that were mostly tiny econo-boxes that had no range or power and cost $40k+. Then the Tesla Model S came out and it was like, duh, put the heavy, expensive batteries in something that’s already naturally heavy and expensive and maybe people will want one! My sticking point that it would be pretty hard to cram in more kWh than an Experia with its bespoke chassis that was made to be electric, even with the Goldwing’s long wheelbase. So you’ve got something that costs more than an Experia, doesn’t go as far or as fast, or handle as well, or have warranty support, etc. It would be a fun project, but maybe not the most practical in a world where dealers are still trying to get rid of their Experias, DSR/X’s and Livewire LW1’s at bargain-basement prices.
Re: Kawi’s hybrid, I believe Kawasaki was just looking for subsidy dollars and to do basic research in case they ever need to go electric for-real. I don’t think they ever intended the Ninja 7 / Z7 HEV’s to sell in large numbers, and they were dreaming if they did. I did a brainstorm about a better hybrid several months ago on this forum and over on ADVRider, and I thought a compelling hybrid motorcycle could be done, but it would require very careful engineering to get better MPG than an NC750X while also being faster and not-too-crazy on price. It would be a big design project and a big financial risk with probably no payoff in sales.
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Existing motor tech works just fine for bikes. Anything involving combustion is a dead end, defeating one of the key issues facing civilisation today, which is decarbonisation of the entire economy. Free energy from the sun is where it's at.
Everyone's main concern still seems to be range and charging speed, and that's almost a solved problem - the tech exists, it's just not yet deployed. Unless Zero go bust in the next 10 years they'll have a genuine 200 mile range bike that charges in half an hour.
Cas :)
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The future of high-MPG lies in streamlining, light weight and small engines. IMHO. ;D Turbocharged and fuel injected.
I agree that streamlining can do a lot for efficiency and I’ve always wanted one, but how do you solve the cross-winds problem? The only solution I can think of are gyroscopes like the Lit Motors one, and that’s kinda like the fuel vapor engine: If it were such a good idea and the tech has been around so long, people would have done it. I’ve been on I-5 with crosswinds trying to blow me into the truck in the next lane, and I’m glad I wasn’t riding a streamliner that day!
Electric is ideal solution as long as you're not covering long distances every day. And have access to power.
"If you change the way you look at things, the things you look at change."
Another possible solution would be to have electric bike, but with a tiny petrol generator. Compact high efficiency (maybe 3 kW) generator that starts automatically and supplements the battery when it drops low, stops at half a charge. Can be manually stopped and started. You could use it to charge the batteries when stationary, but you will lose some efficiency when doing that. On the other hand the generator could be run at maximum efficiency RPM to counteract the losses while charging.
Axial flux motors are not evil. Can be the best option in some circumstances. But to me they are more like a solution in search of a problem.
I thought about the series-hybrid approach, but I looked up the efficiency of the best compact generators, and you’re only going to get 40 to 50 MPG once you convert it back into an electric motorcycle’s traction power. For the best efficiency, you need the gas motor’s to drive the rear wheel for cruising, and let the electric system take the brunt of acceleration. The best I could come up with is a Goldwing-sized bike with a ~400cc gas motor that gets most of its acceleration from the electric motor (EMCE or similar) and has a ~40-mile all-electric range. You’d effectively get something around 90 and 150 MPGe on longer trips, and could cover your local trips on pure electric.
It could work on paper, it would just be hard (and expensive) to design around all the constraints and hit the sweet spot in so many different areas on the first try. Kawi didn’t pull it off, and they’re a huge company with lots of talented engineers and resources. I’d love to see an OEM try to make something like that, but it would honeslty probably flop. The electric enthusiasts wouldn’t buy it because “eww, gasoline,” and the petrol-heads wouldn’t touch it because “eww, electric.” That’s not to say I wouldn’t love to see it happen. I’d buy one.
Existing motor tech works just fine for bikes. Anything involving combustion is a dead end, defeating one of the key issues facing civilisation today, which is decarbonisation of the entire economy. Free energy from the sun is where it's at.
Everyone's main concern still seems to be range and charging speed, and that's almost a solved problem - the tech exists, it's just not yet deployed. Unless Zero go bust in the next 10 years they'll have a genuine 200 mile range bike that charges in half an hour.
Cas :)
I agree with you, but there’s a long transition in the meantime. I once thought that pro-EV policy could and should speed the transition up, but now that I’ve been studying and working sustainable transportation for the last 7 years, I realize that subsidies and mandates are just as often harmful as helpful. Looking at motorcycles, at the current rate of battery density advancement, the Experia could have a 200-mile range by the early to mid-2030’s, but it would still weigh 570 lbs, still cost $24k, and still not have liquid cooling of the battery without giving up some of that range. To have faster charging, 180-mile range or more, similar weight as ICE, and price reductions, that’s at least 20 years from now, and gas tech is also going to improve in the meantime.
So in 20 years, an electric motorcycle can finally have similar range and utility to my 2007 FJR1300, which will be about 40 years old by then. Not saying I wouldn’t rather ride electric, of course, just pointing out that we’ve got a long way to go without some major breakthrough, and it’s just as likely for ICE technology to have a breakthrough during that time as for battery-electric.
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id like to see an electric 3 wheeler. have plenty of room to hide batteries and motors in there and the drive train would not be as critical.
besides we all are getting older, one day we gonna need 3 wheels instead of 2, so lets get the electric ready for that day.
Aaron
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The future of high-MPG lies in streamlining, light weight and small engines. IMHO. ;D Turbocharged and fuel injected.
I agree that streamlining can do a lot for efficiency and I’ve always wanted one, but how do you solve the cross-winds problem? The only solution I can think of are gyroscopes like the Lit Motors one, and that’s kinda like the fuel vapor engine: If it were such a good idea and the tech has been around so long, people would have done it. I’ve been on I-5 with crosswinds trying to blow me into the truck in the next lane, and I’m glad I wasn’t riding a streamliner that day!
Vetter greatly reduced the cross wind issue by making the fairing shorter. Cutting the tail off. If you keep the length of the bike with fairing similar to original length it is not taking much more cross wind than the bike without fairing. Like this guy (Allert) did. Over 230 mpg with 20 year old engine technology and what-looked-to-be-right fairing. https://www.velomobiel.nl/allert/Recumbent%20motorbike.htm With actual CAD designed, aero flow optimized fairing, and better tires, he could probably have gotten over 300 mpg.
Most streamlining fairings seem to be designed for maximum efficiency at max speed. If they are instead designed for average speed, the fairing doesn't need to be as long and can taper more aggressively at the back.
There are varying degrees of streamlining. You don't need to go full fairing streamlining to get some results. There was a Dutch guy that put simple fairing in his Gen2 Zero and reported something like 10% increase in range.
It's awesome to see the ideas and simply brilliant solutions that some people come up with. Even just covering the spokes in the wheels gives few % increase in mileage.
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Kawasaki's ZZR1100 managed a genuine 172mph from just 138rwbhp (both figures tested and verified) back in the 90s. I've owned 4 of them and done a total of maybe 50,000 miles on them and never really noticed any serious problem with crosswinds. 172mph was at least 10mph faster than every other bike at the time.
The side effect of the ZZR's slipperiness was that it also did over 60mpUKg if you rode at the speed limits, when all its contemporaries were lucky to get low 40s.
It strikes me that the ZZR11 fairings would be a great design to fit to a Zero and could be worth another 20 miles of range. The ZZR600 was similarly larger than life managing about 155mph from a measly 90bhp or so.
Cas :)
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Don't forget the 1991 BMW K1. They tried their best to make streamlining a thing, but couldn't find very many customers who wanted to buy them. A nice try, but motorcycle enthusiasts prefer to buy retro, clunky-looking motorcycles, rather than efficient aerodynamic designs. When companies market products they tend to go with ones that are popular with consumers and make a profit for them, not ones that necessarily make logical sense. ;)
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I've never actually compared the range specifications between the SR/F and SR/S, I assumed the SR/S was only marginally better but I was curious just how much difference that fairing makes. Turns out it actually has less range. I don't know what their testing procedure looks like to be able to come up with that result. I've fairly recently put the windscreen back on my DS and tucking down at higher speeds I notice a significant increase in range (and comfort), I couldn't give you exact range estimates but I'm getting home with a lot more charge left on those faster longer distance journeys. It makes me wish I had an S as well of the same capacity so I could just go all out on increasing the efficiency as much as possible.
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When it comes to range, tucking is huge, especially if you are!
Ive seen it create a 10 kw difference in power consumption at times.
Aaron
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Putting small bolt on screen on my SR gives me about 3% increase in range, no tucking.
SR/F vs SR/S is interesting since they both give "380 MPGe (0.62 l/100 km)" as gas equivalent mileage.
If you look closer at the numbers. City/highway mix is nearly the same (What Zero calls "High-Speed Highway Commuting" but if you click the little "i" you see it's actually a 50/50 mix). City only the no fairing bike scores better. Could be because of the less weight. There are no 100% highway numbers, but from the way the other number are one would imagine that the faired bike would score better there.
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I recall that the SR/S was claimed to have 15% less drag in a full tuck ... flat out. So not the greatest or most practical of improvements.
Cas :)
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Vetter greatly reduced the cross wind issue by making the fairing shorter. Cutting the tail off. If you keep the length of the bike with fairing similar to original length it is not taking much more cross wind than the bike without fairing. Like this guy (Allert) did. Over 230 mpg with 20 year old engine technology and what-looked-to-be-right fairing. https://www.velomobiel.nl/allert/Recumbent%20motorbike.htm With actual CAD designed, aero flow optimized fairing, and better tires, he could probably have gotten over 300 mpg.
Most streamlining fairings seem to be designed for maximum efficiency at max speed. If they are instead designed for average speed, the fairing doesn't need to be as long and can taper more aggressively at the back.
There are varying degrees of streamlining. You don't need to go full fairing streamlining to get some results. There was a Dutch guy that put simple fairing in his Gen2 Zero and reported something like 10% increase in range.
It's awesome to see the ideas and simply brilliant solutions that some people come up with. Even just covering the spokes in the wheels gives few % increase in mileage.
Good to know. Maybe a practical electric successor to the BMW C1 or Benelli Adiva will come out someday, after all! I ran into Alan Smith back in c2019 on his green streamlined EVA 107. I wonder if he still rides it? He said it got him about 100 miles of range with the 13.4 kWh battery compared to my SS9 that got 60 on a good day. 100 miles with the 13.4’s quick recharge sounded pretty good to me! The Experia is already more aerodynamic than the EVA so the improvement wouldn’t be as dramatic if someone streamlined it, but I bet 180 miles highway wouldn’t be out of the question.