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@v_oodoo avatar
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'74 50s x3 '87 PK125XL '92 PK50XLS Plurimatic - & - '58 AllState '68 Sprint '66(?) Super125 and '72 DanMotor Super150
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@v_oodoo avatar
'74 50s x3 '87 PK125XL '92 PK50XLS Plurimatic - & - '58 AllState '68 Sprint '66(?) Super125 and '72 DanMotor Super150
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UTC quote
Hal rides his bike to work daily and just finished a new top end etc for nice power upgrade, but...
whereshaldo wrote:
...

My only side note is that my fuel consumption seems to have gotten much worse but also my battery probably needs a touch up of H2O and these Stella gas gauges read like binary switches.

h
With gas prices up there with cheap wine and no sign of coming down any time soon, let's say you have to commute a fair distance and with summer coming, you've started riding your Vespa to work and life is good... Until you start seeing the gas bill Crying or Very sad emoticon and realize it's CHEAPER to drive your newish small gasoline CAR! Facepalm emoticon

So now you wanna build a commuter special bike w/ best gas mileage you can manage. So how would you build up a motor with this in mind? Stock 125 top end? 20/15 carb or small side draft? what about the muff, stock or... ???? Gearing? Would aerodynamic stuff help much? Let's say you wanna go up to only 40ish, maybe close to 50 max on a ~10-15 mile nonfreeway commute for starters. Let's hear what you think of smallies vs largeframes here too, smallie should have the advantage!. Note: I think a 50s might need tuning UP, not down to handle my arbitrary speed requirements. Razz emoticon

And what's the BEST gas mileage you get on YOUR slowest bike?
@sdjohn avatar
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Johnny Two Tone
'15 GTS300, '86 PX125EFL, '66 VBB, '01 ET4
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Johnny Two Tone
@sdjohn avatar
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UTC quote
The stock bikes really already are biased towards fuel economy. The smaller the engine displacement the better. After that, probably should consider tires with low rolling resistance (not knobbies). Keeping the engine running well, clean plug, air filter, etc. will help. After that, you're talking rider behavior - keep engine revs down in the engine's sweet spot, easy on the acceleration, etc. Also keep the cargo (including passengers) as light as possible!
@christopher_55934 avatar
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2007 Stella 225
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@christopher_55934 avatar
2007 Stella 225
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UTC quote
V oodoo wrote:
Hal rides his bike to work daily and just finished a new top end etc for nice power upgrade, but...



With gas prices up there with cheap wine and no sign of coming down any time soon, let's say you have to commute a fair distance and with summer coming, you've started riding your Vespa to work and life is good... Until you start seeing the gas bill Crying or Very sad emoticon and realize it's CHEAPER to drive your newish small gasoline CAR! Facepalm emoticon

So now you wanna build a commuter special bike w/ best gas mileage you can manage. So how would you build up a motor with this in mind? Stock 125 top end? 20/15 carb or small side draft? what about the muff, stock or... ???? Gearing? Would aerodynamic stuff help much? Let's say you wanna go up to only 40ish, maybe close to 50 max on a ~10-15 mile nonfreeway commute for starters. Let's hear what you think of smallies vs largeframes here too, smallie should have the advantage!. Note: I think a 50s might need tuning UP, not down to handle my arbitrary speed requirements. Razz emoticon

And what's the BEST gas mileage you get on YOUR slowest bike?
Honda 125 Super Cub 110- 125 mpg and 60+ MPH GPS verified. This was on a scooter more of a moped? I borrowed for a few weeks. If you take a peak at fuelly.com you can see scooters and real world averages.

I had also contemplated a Honda cb125F, basically same little less mpg.

Started a car pool with 5 other people we work same hours, never pursued it. We get about 160 mpg, 5 people x 32 mpg?
@christopher_55934 avatar
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2007 Stella 225
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@christopher_55934 avatar
2007 Stella 225
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UTC quote
sdjohn wrote:
The stock bikes really already are biased towards fuel economy. The smaller the engine displacement the better. After that, probably should consider tires with low rolling resistance (not knobbies). Keeping the engine running well, clean plug, air filter, etc. will help. After that, you're talking rider behavior - keep engine revs down in the engine's sweet spot, easy on the acceleration, etc. Also keep the cargo (including passengers) as light as possible!
Closed loop fuel injection system.

Charging system like an alternator that isn't always generating electricity and wasting gas.

Computer controlled electronic ignition with variable valve timing.
@sdjohn avatar
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Johnny Two Tone
'15 GTS300, '86 PX125EFL, '66 VBB, '01 ET4
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Johnny Two Tone
@sdjohn avatar
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UTC quote
Christopher_55934 wrote:
Closed loop fuel injection system.

Charging system like an alternator that isn't always generating electricity and wasting gas.

Computer controlled electronic ignition with variable valve timing.
Sure but I don't think voodoo is looking to leave the vintage world, just wondering how to optimize it.
@safis avatar
UTC

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1979 P150X, 1983 P200E, 1987 PK125XL Elestart, 1988 T5, 1995 PX200E, 2011 Yamaha Fazer 600 S2
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@safis avatar
1979 P150X, 1983 P200E, 1987 PK125XL Elestart, 1988 T5, 1995 PX200E, 2011 Yamaha Fazer 600 S2
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UTC quote
sdjohn wrote:
Sure but I don't think voodoo is looking to leave the vintage world, just wondering how to optimize it.
Why leave the vintage world?? A friend sent these. From SIP's recent open day. F.I. based on a Cosa engine…
Forum member supplied image with no explanatory text
Forum member supplied image with no explanatory text
@greasy125 avatar
UTC

Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
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Sergeant at Arms
@greasy125 avatar
Weird 80's Vespas & Cool Vintage Lambrettas
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UTC quote
first, I don't think aero really plays any part here due to the speed and type of riding.

(Patrick, feel free to correct me here)

on a smallie, you have the advantage of weight. but like you said a 50/90 or possibly 100 would need tuning. any of those with a 4spd and 90/100 primary would be the start. then either O-tune the 100 barrel or snap on a 102 on the 50 or an ET3, Olympia, DR on the 90/100. electronic ignition, and a touring weight flywheel. carb, either a 19/19 or an aftermarket 19/20. a stock banana will be more than sufficient.

the thing is, the 50 with a 102 wants to rev to make power. so if you have the cubes, you don't have to twist the throttle and burn the gas, so I'd go 100 or a ET3/etc. but again, you don't have to go fast. but a stock 50 special is SLOW SLOW.

on a large frame, a stock 2 port with a 20/17 on 8's might be swell. or just a straight up standard P125 will get you there easy. a P2 with a 20/20 would do, but might eat a little more gas.

from there, I think you're into fractions of percentages on returns. like John said, low rolling resistance tires, weight reduction, riding style.
UTC

Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
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Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
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UTC quote
V oodoo wrote:
Hal rides his bike to work daily and just finished a new top end etc for nice power upgrade, but...



With gas prices up there with cheap wine and no sign of coming down any time soon, let's say you have to commute a fair distance and with summer coming, you've started riding your Vespa to work and life is good... Until you start seeing the gas bill Crying or Very sad emoticon and realize it's CHEAPER to drive your newish small gasoline CAR! Facepalm emoticon

So now you wanna build a commuter special bike w/ best gas mileage you can manage. So how would you build up a motor with this in mind? Stock 125 top end? 20/15 carb or small side draft? what about the muff, stock or... ???? Gearing? Would aerodynamic stuff help much? Let's say you wanna go up to only 40ish, maybe close to 50 max on a ~10-15 mile nonfreeway commute for starters. Let's hear what you think of smallies vs largeframes here too, smallie should have the advantage!. Note: I think a 50s might need tuning UP, not down to handle my arbitrary speed requirements. Razz emoticon

This goes against everything I do but knowing how to make faster includes making more efficient but with significant diversion. For just efficiency all focus has to be on reducing internal losses and running on the hot end of acceptable.
The list goes something like this (sure a few things are missing)
- Engine in perfect working order and sealed tight
- Reduce piston weight
- Increase gear ratio
- Bigger wheel diameter and less width
- Reduce compression significantly while closing squish clearance and tightening squish angle
- Cylinder port timing as low as possible
- Box exhaust with smaller outlet pipe or squashed flatter
- Ignition timing advance as low as needed to get max power
- Change to Mosfet regulator
- All jetting on the lean side of sufficient (think stock setups especially LML)

Sure there's more for this list but you get the idea
V oodoo wrote:
And what's the BEST gas mileage you get on YOUR slowest bike?
They are all bad except my fuel injected 1100, which can do 70 mpg if I can ride it slow enough.
@jimvanmorrissey avatar
UTC

Addicted
Vespa PX200
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@jimvanmorrissey avatar
Vespa PX200
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UTC quote
This'll sound counterinuitive, but go-fast parts have made for some fuel savings. At least while cruising around at 80 km/h, in line with the requirements at the top of this thread. Holding that speed on a stock setup needs something close to WOT, but if you've tuned things up to 20hp or more, you can hold it at 5000RPM by way of something like quarter throttle.

I learned this last summer when I'd taken my new rig (a Malossi 221, matched ports, Polinibox) out on a lazy back-road break-in cruise at 80-90km/h, and after 120km or so I'd pulled over for gas. Turrned out I'd only burned 5 litres. That makes out for a range just shy of 200km. Most folks on PX200's are only getting +-185km on a single tank (provided they're not ragging it at WOT.)

This setup does get way worse economy than stock while crusing at or near full throttle and while racing between stoplights. But for sedate touring it's great.
⚠️ Last edited by JimVanMorrissey on UTC; edited 1 time
@subetherbass avatar
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1997 Italjet Formula 125, 2 matching N.Z. '69 VBC Super, 177cc Racer, VespaCross Bodge, Puch SRA150, Piaggio Zip 100! & others
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@subetherbass avatar
1997 Italjet Formula 125, 2 matching N.Z. '69 VBC Super, 177cc Racer, VespaCross Bodge, Puch SRA150, Piaggio Zip 100! & others
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UTC quote
If you want to get more miles out of a tank it's pretty simple... get a bigger tank!
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Veni, Vidi, Posti
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Veni, Vidi, Posti
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UTC quote
Of all the 2 stroke scoots I have owned, the 2003 Stella was the most fuel efficient. But I guess it was built that way from the start with just regular maintenance done on my part.
@sdjohn avatar
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Johnny Two Tone
'15 GTS300, '86 PX125EFL, '66 VBB, '01 ET4
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@sdjohn avatar
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UTC quote
Better bearings and straight cut gears will help. Anything for less friction.
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2 - Many
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@scooterraton avatar
2 - Many
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UTC quote
Riding style, weight and air pressure are probably the biggest factors.

I'm one of those that really doesn't care about mileage except for engine performance. No matter what, some of my scooters, especially the kitted ones, are still get wound out and hammered.

It's just not possible for me to ride "fuel efficient" on a Dragster 180, Malossi 166, or Malossi 210. It's just not gonna happen!
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Molto Verboso
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Molto Verboso
@rob_hodge avatar
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UTC quote
The most important variable I have found is induction.

On a vespa, reed engines, even when highly tuned, get far better gas mileage than any other setup.

My old mass race bike with an SIP pipe, 28 mikuni, malossi reed, and a 177 polini actually got about 50% better gas mileage than a clubmates beater stock p200 back in the day on long multi-state trips to rallies.


If you wanted best driveable gas mileage on a vespa, get a Stella. The lml 5-port reed engines were specifically setup for the Indian market where economy is the #1,#2 and #3 concern. Real world 60-110 mpg isn't unheard of. Even kitted I doubt I got less than 60 on mine.
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Veni, Vidi, Posti
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Veni, Vidi, Posti
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UTC quote
Good to see you on here Mr. Hodge. About my comment above, I used to get 75 mpg and sometimes above that on my Stella. Basically a stock machine with a non-cat box pipe and upjet.
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79 P200E (Ruby), 62 Allstate (B-62)
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@qascooter avatar
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UTC quote
The Bajaj 4T got excellent gas mileage stock. I was getting 80+, which I thought was amazing. After I made a few changes, I'd still get 60+....

But alas, not so many of them around anymore...
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parallelogramerist
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parallelogramerist
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UTC quote
I only paid attention to the mileage on my 200 engines. And it fluctuates a LOT depending upon how I twist the throttle. For instance, I was riding my stock P200 (with a Sito+) on I-5 from Seattle to west of Portland. It was about a 200 mile straight shot of interstate. I had a little bit of a headwind, so I was in a full tuck struggling to maintain 60mph. I had the throttle all the way open, and it was delivering me a dismal 30mpg. After filling up at a gas station, I drafted off the back of a large semi. And when I mean drafted off the back, I was waaaaay too close to be safe (probably something like 10') but since I was so dang close, I had absolutely zero headwind. I could sit straight up on the seat after that with the throttle barely cracked, still going 60mph, but I was getting 90mpg. Normal highway riding on my P200 (without headwinds) I get about 50~ish MPG at 60mph. With my PX210 (cut crank, rotary induction, 30 mil dellorto) I get around 55 MPG at 60MPH. Reason being is that the engine has more HP, so it doesn't take as much twist of the wrist to keep my speed up.

Another for instance-
My friend and I did a 1300 mile road trip. He was on a stock 2005 PX150 (with a Sito+), and I was on my stock P200. Since the top speed on a stock PX 150 is about 50mph, we kept our pace at around 45mph. Going easy with twisting my throttle, I was getting about 70~75mpg. But it's really difficult to only go 45mph and pretty much impossible to ride that slow on any highway. Since we were riding on highway 101, we could kinda get away with it. Lots of times the RV'ers were traveling at that same speed.
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Hooked
1964 v90, 1970 VBC, lots of dumb twist n go toys
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@thomashsb avatar
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UTC quote
Aerodynamics definitely make a big difference but that's hard to change. At 6'3" getting tucked down right behind the fairing adds around 5 to 10 mph on my top end on my little bikes.

Probably need a dustbin fairing to make that reduced drag practical and not give yourself a sore back.
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UTC quote
V oodoo wrote:
And what's the BEST gas mileage you get on YOUR slowest bike?
I have no idea. I'm not even sure how to calculate it. It's something I never considered worrying about. The thing I'm worried about is the day that I won't even be able buy it because it won't be sold anymore. We will all be less noxious versions of the "smokers" in Waterworld.
@chandlerman avatar
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Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
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@chandlerman avatar
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UTC quote
As others have said, I used to get 60-75 MPG riding aggressively in downtown Chicago on my Stella when the motor was stock.

So if you put a stock Stella motor in an older frame like a Sprint, that'd reduce your weight by close to 50 lbs (dry weight Stella is 228lbs, dry weight VBB is like 180. GL or Sprint is still under 200, I think, but you get 10" wheels).
@xantufrog avatar
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1980 P200E - "Old Rusty", 1976 ET3 Primavera
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@xantufrog avatar
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UTC quote
JimVanMorrissey wrote:
This'll sound counterinuitive, but go-fast parts have made for some fuel savings. At least while cruising around at 80 km/h, in line with the requirements at the top of this thread. Holding that speed on a stock setup needs something close to WOT, but if you've tuned things up to 20hp or more, you can hold it at 5000RPM by way of something like quarter throttle.
Yeah this is definitely a thing - I'm going far off on "make and model" here but I tuned my SAAB a few months back and although it certainly *can* get worse fuel economy than it did stock if I push it, overall I'm getting better fuel economy in my normal driving routine because I don't have to crack the throttle nearly as much
@vintage_red_matthew avatar
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MV Santa
GTS250, 1975 VBC, 1980 P200E cutdown
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@vintage_red_matthew avatar
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UTC quote
I was reading the service manual for my VBA and it said that it was supposed to get 100mpg.

No way, I said.

I looked deeper in the manual for how to test the fuel mileage and, paraphrasing it said to go 20 mph and no stops.

I'm not sure where I can go 20 mph with no stops for long enough to get a good mileage test but I found a different way to measure it. I would turn the fuel tap off at various speeds and count how many power poles would go by until the float bowl was empty.

It was a long time ago and I don't remember the exact numbers but the book was correct. I could go almost twice as far at 20mph than 40.

The problem is, of course when you are going 20mph it feels like you could get off and run faster.
@xantufrog avatar
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Moderibbit
1980 P200E - "Old Rusty", 1976 ET3 Primavera
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@xantufrog avatar
1980 P200E - "Old Rusty", 1976 ET3 Primavera
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UTC quote
vintage red matthew wrote:
I'm not sure where I can go 20 mph with no stops
Isn't that just the natural outcome of riding a VBA and having old drum brakes? Laughing emoticon
@chandlerman avatar
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Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
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Lucky
@chandlerman avatar
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UTC quote
vintage red matthew wrote:
The problem is, of course when you are going 20mph it feels like you could get off and run faster.
With a pogo stick fork and anything but the smoothest of roads, 20mph is the new 60mph.
@axman88 avatar
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Stella 4T, 2011
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Location: Chicago, IL
 
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@axman88 avatar
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UTC quote
4 Stroke, low RPM single cylinder engine with heavy flywheel and closed loop fuel injection.

I get around 80 mpg with my 150cc 2012 Stella 4T, which, of the above, only has 4 stroke going for it.

But, my 2012 Royal Enfield Classic 500, which has everything on the list, and 499 ccs, gets around 65 mpg.

Both machines are ridden in 99.5% urban city street environment (Chicago). I estimate that more than half of my riding time is spent idling at traffic lights, or slowing down / speeding up at stop signs.

I consider low rpm running to be a critical factor in fuel economy, because 14.7% of volume is fuel. Displacement is fixed for any engine, but rpm determines the number of gulps that my engine will be taking in a given period. The heavy flywheel helps keep the engine running at slow speed, and smooths the torque delivery. A single cylinder has the smallest area of sliding and bearing surface for its displacement.

This is the most economical production moto ever built, that I'm aware of, the diesel powered Royal Enfield Taurus: https://www.rideapart.com/features/502321/royal-enfield-diesel-powered-bullet-taurus/ 200 mpg is not bad! It's out of production, and won't meet current emissions standards, but diesel conversions are still being made, onsey twosey. Not many are built specifically with economy in mind, however http://www.dieselbike.net/motorcycles/motorcycles.htm
@swiss1939 avatar
UTC

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P208, Stella VMC Stelvio 187, Stella 150, VNX1T, V9A1T, V9B1T, 02 Sportster XLH1208
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@swiss1939 avatar
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UTC quote
axman88 wrote:
4 Stroke, low RPM single cylinder engine with heavy flywheel and closed loop fuel injection.

I get around 80 mpg with my 150cc 2012 Stella 4T, which, of the above, only has 4 stroke going for it.

But, my 2012 Royal Enfield Classic 500, which has everything on the list, and 499 ccs, gets around 65 mpg.

Both machines are ridden in 99.5% urban city street environment (Chicago). I estimate that more than half of my riding time is spent idling at traffic lights, or slowing down / speeding up at stop signs.

I consider low rpm running to be a critical factor in fuel economy, because 14.7% of volume is fuel. Displacement is fixed for any engine, but rpm determines the number of gulps that my engine will be taking in a given period. The heavy flywheel helps keep the engine running at slow speed, and smooths the torque delivery. A single cylinder has the smallest area of sliding and bearing surface for its displacement.

This is the most economical production moto ever built, that I'm aware of, the diesel powered Royal Enfield Taurus: https://www.rideapart.com/features/502321/royal-enfield-diesel-powered-bullet-taurus/ 200 mpg is not bad! It's out of production, and won't meet current emissions standards, but diesel conversions are still being made, onsey twosey. Not many are built specifically with economy in mind, however http://www.dieselbike.net/motorcycles/motorcycles.htm
Those are some good stats on mpg! Think we are all discussing more along the lines of how to rebuild/tune our existing two stroke motors for better economy, as opposed to what we normally do, which is build them for high performance gas guzzling! Not so much just swapping out a 2T motor for a 4T motor as that would be the easy way out. At least for me, and I suspect many others on here as well, its more about the process of achieving the goal than it is about the goal itself.


Its an interesting question that I personally think is a really cool project to try to strive for. It takes some restraint to not go all out on these projects, and an equal amount of restraint to not wind these engines out as hard as you can as fast as you can. So its an exercise in doing everything counter to what many of us normally want to do.

@chandlerman avatar
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Lucky
76 Sprint V, 63 GL, 62 VBB, 05 Stella, 66 Smallstate, 79 P200E, 66 Lammy S3
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Lucky
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UTC quote
swiss1939 wrote:
Think we are all discussing more along the lines of how to rebuild/tune our existing two stroke motors for better economy, as opposed to what we normally do, which is build them for high performance gas guzzling!
Yup. And it's all good, so long as I only have to do it hypothetically! Laughing emoticon
OP
@v_oodoo avatar
UTC

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'74 50s x3 '87 PK125XL '92 PK50XLS Plurimatic - & - '58 AllState '68 Sprint '66(?) Super125 and '72 DanMotor Super150
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UTC quote
axman88 wrote:
.... ridden in 99.5% urban city street environment (Chicago). I estimate that more than half of my riding time is spent idling at traffic lights, or slowing down / speeding up at stop signs.

I consider low rpm running to be a critical factor in fuel economy, because 14.7% of volume is fuel. Displacement is fixed for any engine, but rpm determines the number of gulps that my engine will be taking in a given period. The heavy flywheel helps keep the engine running at slow speed, and smooths the torque delivery. A single cylinder has the smallest area of sliding and bearing surface for its displacement.

...
Good info I can relate to, thanks! Reminds me of my Greek P200 which I can putt around the neighborhood in 3rd and 4th, I rarely use 1st or even 2nd much with all that torque if I'm not in a hurry. Gas is now about $9.50 a gallon in Greece so it adds up pretty fast.

Has anybody here use both a 20/20 and a 24/24 on a P200 who can tell us if it made much difference in gas mileage?
@axman88 avatar
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Member
Stella 4T, 2011
Joined: UTC
Posts: 36
Location: Chicago, IL
 
Member
@axman88 avatar
Stella 4T, 2011
Joined: UTC
Posts: 36
Location: Chicago, IL
UTC quote
swiss1939 wrote:
Those are some good stats on mpg! Think we are all discussing more along the lines of how to rebuild/tune our existing two stroke motors for better economy, as opposed to what we normally do, which is build them for high performance gas guzzling!
Yes, I see that now, although on my first speed read, I interpreted the question as being more open ended.

I'm not really familiar with Vespa engine design, but it seems that fuel economy is quite limited on most two stroke designs by the lack of proper valving, and even more so, by the difficulty of simultaneously emptying a volume of exhaust gas and filling it with mixture.

With fuel prices going the way they are, the solution I would take would be to buy something like a used Honda Helix to use for my commuting, and leave my classic 2 stroke in the garage. At $5/gallon, my 2nd hand purchase would be paid off in something like 5000 miles of riding, and my classic's value would be preserved for leisurely evening and weekend showing off. My 250 cc Honda beater would reliably take the punishment of my all weather, rush hour commuting, and deliver 60+ mpg doing it.
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Ossessionato
Vespas 1964 GS160, 1965 SS180, 1977 V9A1T, 1983 PX150E
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Location: Siam
 
Ossessionato
Vespas 1964 GS160, 1965 SS180, 1977 V9A1T, 1983 PX150E
Joined: UTC
Posts: 2537
Location: Siam
UTC quote
Put a small frame engine into a large frame, or just ride a small frame with a small frame engine in it. 😑
OP
@v_oodoo avatar
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Style Maven
'74 50s x3 '87 PK125XL '92 PK50XLS Plurimatic - & - '58 AllState '68 Sprint '66(?) Super125 and '72 DanMotor Super150
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Style Maven
@v_oodoo avatar
'74 50s x3 '87 PK125XL '92 PK50XLS Plurimatic - & - '58 AllState '68 Sprint '66(?) Super125 and '72 DanMotor Super150
Joined: UTC
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Location: seattle/athens
UTC quote
I think you may be on to something here!

External inline image provided by member with no explanatory text

If I use the rare and famously frugal SHB 16.10 carb, what pipe might be best for low end grunt?
@ray8 avatar
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Molto Verboso
Joined: UTC
Posts: 1888
Location: Los Angeles
 
Molto Verboso
@ray8 avatar
Joined: UTC
Posts: 1888
Location: Los Angeles
UTC quote
V oodoo wrote:
I think you may be on to something here!

If I use the rare and famously frugal SHB 16.10 carb, what pipe might be best for low end grunt?
Just from a mileage standpoint(not $), the Smartcarb claims 30-50% better mileage.

If true, rough guess is it would take 4 years of daily riding to pay that inve$tment off, assuming gas prices stay the same.
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