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-   -   Real world hwy P&G mpg for 250-650cc cycles? (https://ecomodder.com/forum/showthread.php/real-world-hwy-p-g-mpg-250-650cc-25531.html)

stillsearching 04-13-2013 02:44 AM

Real world hwy P&G mpg for 250-650cc cycles?
 
After further researching into my various options I think i'm finally narrowing down my choices. If i'm reduced to 30mph commuting i'll just go with a 2hp assisted bicycle. Motorcycles that have to struggle to keep up on the highway just aren't much point right now and i'm guessing in the real world will probably be worse MPG by being run flat out vs a pulsed and glided bigger bike. Although there are bikes that i've found I like just fine even in the 125cc class, i'm primarily to be riding for mileage instead of fun and don't want to spend $2000+ right now.

So narrowing this down further. Can anyone with a bike in that approximate range share what kind of highway figures they get? People averaging 55mph or faster only I mean. I'm hoping that using P&G I might be able to hit 80mpg even with a 650cc vtwin or so. Also on an older/less valuable standard i'm potentially more willing to do things like drill holes and make up custom fairings and such to improve the aero which I don't really want to do on a newer nice bike that I want to hold all it's value. Plus the larger displacements have enough torque to move around the mini-trailers I was asking about without completely falling over likely even P&G'ing them around even uphill if needed.

So am I probably right that, using pulse and glide, the larger bikes will probably get about the same mileage as the smaller ones? Ie a Ninja 650 vs a Ninja 250. I'm assuming specific fuel consumption per HP is pretty similar, and the faster acceleration during pulse time just puts energy into the momentum that much quicker not really using any more gas to get from 45-75mph for instance assuming total weight is about the same.

Does anyone want to recommend specific reliable used motorcycles that would be suited to pulse and glide highway riding like this? Ideally bikes obtainable for under $1000 or so or maybe $1500 at the max? Even dual sports/street legal dirt bikes are fine, actually if there is one it might even be better since i've heard them recommended for training to get used to low traction conditions and to have a bike that isn't phased by being dropped.

Frank Lee 04-13-2013 02:47 AM

P & G on a bike sux. Didn't we have this conversation already?

stillsearching 04-13-2013 02:56 AM

We probably covered similar ground but i've been out of the loop for several months. : P But you don't have to respond if it's just a rehash, i'll reread all older stuff before long if it was partially covered. I'm just endlessly narrowing down my options, exploring one area, then another, then returning to what seems to bear the most fruit. If I want to have a motorcycle at all it's seeming to need an MPG range that it wont have without either aeromodding or P&G, and I wont have the opportunity to aeromod it at first yet I still need the fuel savings.

renault_megane_dci 04-13-2013 03:49 PM

I would go for a 650 single because basically the more powerful a bike, the least MPG.

Remember, for the three last decade, bikes had been tuned for as much power as possible.

A 600 4 cylinder doesn't have much more torque than a 650 single but it does its peak torque at twice the RPM !

pete c 04-13-2013 08:29 PM

A friend has a DRZ400. Says he gets near 70 mpg and absolutely loves it. I think a 400 is a great size for the road. Enough power for comfy highway cruising, but not more than needed.

Might have trouble getting one in your price range though.

alvaro84 04-15-2013 10:33 PM

Quote:

Originally Posted by Frank Lee (Post 366447)
P & G on a bike sux. Didn't we have this conversation already?

Why? It still works pretty well for me, especially on hills.

@stillsearching - I often do things like 45..60-65 mph P&G with a fuel injected 650 single. It's somewhat slower than your target speed, but this is the info I have. It's still in my log, I still can do 80+ mpg in good weather. This year I've just reached it.

(But when I don't P&G I still coast when I want to slow down. And when I don't P&G I tend to ride slower than that 55mph, if the traffic permits, 45-50 is about the smoothest range of 5th gear, at ~3000-3200rpm. This is why I prefer deserted back roads.)

Frank Lee 04-16-2013 12:59 AM

Why? Because bikes have relatively high rolling and aero resistance and relatively low weight. Sure, hills are one thing but out on the flats, bikes glide down like they are dragging anchors compared to cars, and even cars suck.

alvaro84 04-16-2013 09:33 AM

Quote:

Originally Posted by Frank Lee (Post 366858)
Why? Because bikes have relatively high rolling and aero resistance and relatively low weight. Sure, hills are one thing but out on the flats, bikes glide down like they are dragging anchors compared to cars, and even cars suck.

It's all true, yet it works for me at the bottom of 5th. Of course it can benefit the most when it's hilly, I often don't bother with it on flat ground.

Another use: following the hectic flow of city traffic. They won't keep a steady speed.

And one more thing, when it's really useful: when you can't shift into the top gear. If it's a stronger bike, it runs awfully inefficient in lower gears. And even the aero drag is less down there. City traffic, again. Or many sharp turns.

3-Wheeler 04-16-2013 01:43 PM

Quote:

Originally Posted by Frank Lee (Post 366858)
Why? Because bikes have relatively high rolling and aero resistance and relatively low weight. Sure, hills are one thing but out on the flats, bikes glide down like they are dragging anchors compared to cars, and even cars suck.

Frank,

I have to agree with you.

I have an old VF500 with a full size custom fairing, and also drive a Honda Insight.

Comparing the rolling resistance and/or air drag between the two is just silly.

At the same speed of about 30 mph, the car will easily coast a half mile, while the bike can barely coast 1/4 mile.

On the way to work, there is a slightly downhill section of road and the car gains speed with the engine off, and the bike will only maintain constant speed when I turn the engine back on and apply power.

The air drag on the motorcycle is so high that I doubt P&G is gaining much for the motorcycle. The car is another matter entirely.

EOC'ing from 33 to 20 mph on a hot summer day, the car usually gives 150 mpg.

Jim.

stillsearching 04-16-2013 04:49 PM

Well that's part of why i'm asking - even if P&G sucks is it still worth doing? :)

I'll state a bit more to see if it helps clarify. Most of all I would LOVE to have SFC figures for modern bikes. For instance on cars it's pretty much a given that they'll be the most efficient fuel use, per HP used, maybe around 2000rpm or so. At 1000rpm it will suck. At 5000rpm it will suck. But bikes have such an incredibly wide range, like the Ninja 250 with what, 13,000rpm redline?? I don't know where the ideal part of the curve is for such an engine. I would like to have something with enough power and gear, to put it in that sweet spot of the curve for 55-75mph range approximately. If a 500 is more efficient putting out a 15-20hp load than a 250 is (being run too hard) the 500 will probably get better mileage under those conditions - this i've finally understood.

I'm strongly considering aeromodding a bike (more willing to do with an uglier, cheaper, older rattier bike than something new and slick like a Ninja) but my fab skills currently suck so I don't want that to be a first or immediate project, it might wait a year before I do it, and i'm hoping the MPG of the bike will pay for itself before then.

Not looking at any kind of 600cc super sport - when I say 650 I mean the big singles and twins mostly, torquier stuff.

I'm becoming more convinced that I need more displacement - the guy with the 180mpg 90cc ultraslicked scooter is cool, but i dont want to see it on a mild hill and I know for a fact i'll be moving stuff by utility trailer, so the usability requirements are pushing me away from the smallest displacements afterall after struggling to find a way to make it work. Anything from 20-60hp potentially, just wanting at least 20hp to get around with some authority without overstressing things. A 250cc may still be okay though.

alvaro84 04-16-2013 05:05 PM

Quote:

Originally Posted by stillsearching (Post 366966)
Well that's part of why i'm asking - even if P&G sucks is it still worth doing? :)

Well, it depends. When I didn't use coasting, it was rare to reach 3l/100km. When I started to do so, it became something basic, 'good' is well under that. Now 'good' is under 2.8l/100km. Very good is like 2.6-2.7. PR is 2.38 (I may not reach it again). But I need long trips and hills or mountains for the for 'very good' tanks, so I can't compare them directly.

Of course only a part of my coasting is P&G, but there are circumstances where P&G is a natural way to follow the terrain or the traffic, so I P&G there even when I don't do otherwise.

And I almost always P&G if I can't shift into at least 4th (topmost minus one).

And the main problem is that my bike doesn't have any kind of FCD.

Plus side of flat road P&G:
- A few percent FE gain over the bottom of highest gear. Sometimes more. Surely depends on the way you do.
- Presumably even more gain when in a lower gear (some FCD would help!).
- Keeps you awake after night shifts (no joking here :D).
- The ability to choose which hand you want to rest (can really help when you ride all day long)
- Stronger grip in the long run :D

Minus side:
- Tiresome and takes a bit of your attention.
- Wears dropout bearing (though I really don't know how much - Teresa's lasted for ~111000km).
- Surely wears rear tire more than constant low speed riding.

stillsearching 04-16-2013 07:08 PM

Why would the rear tire and dropout bearing wear more, are the loads from extra bursts of acceleration that substantial? What's an FCD? (fuel use instrumentation?)

I'm willing to put in an ignition cut off and play around with streamlining the bike, within what my limited fabrication skills are capable of creating. Since it sounds like bikes are even worse than I thought aero-wise, even lower quality aero is probably a huge improvement. My goal would be 100mpg with a larger bike if I can reach it since that's when it starts to pay for itself, even with summer only commuting, in a fairly short period of time. I'd want to make the fairings easily removable so I don't have to always ride that way. (for instance if i got say some 400cc dual sport I could have it on to putter the highways yet remove it to actually go camping since the aero stuff might get in the way... of the riding experience if not other things) Really wish I had SFC figures so I could know what RPM range it would want to run in through, rather not change that if I can help it.

alvaro84 04-16-2013 07:20 PM

Quote:

Originally Posted by stillsearching (Post 366986)
Why would the rear tire and dropout bearing wear more, are the loads from extra bursts of acceleration that substantial?

The bearing is worn by the very act of holding the clutch. The rear tire - hm, it would be nice to do some math about it. Until someone competent does it, please don't take it as a fact, it's more like a theory of mine. But applying force to the road (accelerating or braking) wears the tire more than just rolling, and I suspect that wear is not linearly proportional with the applied force (like aero drag is calculated from the square of speed and road damage is proportional with the 4th power of weight per axle). So acceleration/glide cycles probably won't give the same average as the less force needed for keeping the same unchanged speed. Sorry, I don't know the necessary background :o

stillsearching 04-16-2013 08:26 PM

My guess would be the bearing shouldn't wear much more than you'd get in city traffic then since one is constantly pawing the clutch, and the tire should spend little enough time under extra power (just gliding) that the life difference should be negligible i'd think.

alvaro84 04-16-2013 08:47 PM

I hope so :)

It's still interesting how these Heidenau K73 rears wear now: it's a commonplace that a front tire serves twice the time a rear - but with these I've worn 3 rears for a single front. It's true, though, that my Metzeler Z6s wore at once, the front didn't last any longer than the rear.

You may be right about city traffic, that needs much more shifting than the way I'd use the bike if I didn't glide: most of my commute is out of the city and I only have to get out of 5th in the 2 villages before I reach the edge of the city.

And I try to avoid bigger cities/towns during touring too.

sendler 04-18-2013 08:27 AM

PnG works the same for a motorcycle as it does for a car. Just at a higher frequency because the bike weighs so much less. So there is little time between cycles to bother to shut the engine off with a bike. Only during down hills. Which may not be ideal for reasons of wear as there are some oil pressure lubed bearings in motorcycle trans. But they are roller bearings so they should survive unharmed on a residual oil film for quite a while. I only shut the engine off at stop lights and during competition.

MPG_Plus 04-23-2013 12:01 AM

250 ninja work's well for me
 
My 4 week average is 108 MPG after changing to 16/33 sprockets and a non-oring chain. Typically may ride to work is mixed city driving with a 7 miles at 55 . Coming up to lights and down hills I P&G and the new non-oring chain glides at least twice as far. I have calculated top speed at about 93 MPH in 3rd gear but haven't tried it yet. My point being is that I have no problem keeping up with traffic you just have to pick the right gear. In slow traffic I am typically in sixth gear at 33 MPH. If I were to start again I would probably go with the new ninja 300 but it isn't exactly cheap. If I ever get into serious aero mods I would gear the 250 higher yet.:rolleyes:

renault_megane_dci 04-23-2013 05:06 AM

Please, start a fuel log.

MPG_Plus 04-23-2013 09:11 AM

Where's the fuel log
 
I have my own spreadsheet and do not use this site very often. I see several "fuel logs" that have the same look. Where do I find this fuel log?

renault_megane_dci 04-23-2013 04:09 PM

click garage in garage&tools, add a vehicle, make a fuel log entry (catch up with your older fuel log since there is nothing on TV anyway ;-) )

MPG_Plus 04-28-2013 11:50 AM

Fuel log issues
 
I noticed that the option to import using cut and paste does not work, at least for me on my computer using firefox or MS explorer. Also the lifetime average and the three last tanks and last 90 days is off by a few miles per gallon. When shooting for triple digits this make a difference to me. The current mileage is fine and each of the individual data points. I can't see entering a bunch of previous data until that is fixed.

;)

Honda100 05-06-2013 01:31 AM

250 Nighthawk gets around 71-80 mpg for me, very soft cruising. 55-67 ish when getting on it.

P-hack 12-09-2013 09:46 AM

most of my riding is around town, so less aero penalty. P&g helps me get into triple digit mpgs on small bikes. My v65 sabre is just a pig no matter how you drive it. But per the OP, hiway is going to see reduced returns certainly (excepting large hills)

jkv357 12-09-2013 10:38 AM

I guess I haven't chimed-in on this thread yet, so to answer the initial question -

My 2006 Suzuki SV650 N (F.I., no fairing) that's geared-up 1T on the countershaft gets about 55 MPG on the Interstate at 70-75 MPH. Best its done is 62 MPG during some moderate back road riding in the 50-70 MPH range.

That's on ethanol-free 87 octane.

I don't P&G with it, as it's a V-Twin and slows immediately/drastically when you roll off the throttle. It will return 50 MPG in town also, using moderately quick acceleration then a smooth cruise at lower RPMs with minimal throttle opening.

alvaro84 12-16-2013 12:11 AM

Quote:

Originally Posted by jkv357 (Post 402382)
I don't P&G with it, as it's a V-Twin and slows immediately/drastically when you roll off the throttle.

Haven't you forgotten about something? Like the clutch lever ;)

jkv357 12-16-2013 11:42 AM

Quote:

Originally Posted by alvaro84 (Post 403097)
Haven't you forgotten about something? Like the clutch lever ;)

Nope.

I don't coast with the clutch in on a cycle.

P-hack 12-16-2013 12:38 PM

I would say Yes. It isn't G (as in P&G) if you aren't in neutral or holding the clutch in. You are engine braking which is still braking.

renault_megane_dci 12-18-2013 03:48 PM

With my car, I don't P&G anymore because since it is able to cut off fuel when pedal is depressed, it seems more rewarding.

No use on carbed engine obviously

serialk11r 01-17-2014 11:56 PM

Quote:

Originally Posted by stillsearching (Post 366966)
Most of all I would LOVE to have SFC figures for modern bikes. For instance on cars it's pretty much a given that they'll be the most efficient fuel use, per HP used, maybe around 2000rpm or so. At 1000rpm it will suck. At 5000rpm it will suck. But bikes have such an incredibly wide range, like the Ninja 250 with what, 13,000rpm redline?? I don't know where the ideal part of the curve is for such an engine. I would like to have something with enough power and gear, to put it in that sweet spot of the curve for 55-75mph range approximately. If a 500 is more efficient putting out a 15-20hp load than a 250 is (being run too hard) the 500 will probably get better mileage under those conditions - this i've finally understood.

Bikes have no variable valve timing, so there is considerable (undesirable) EGR at lower loads for quite a chunk of the rev range, and this is probably the main thing that robs efficiency. In car engines the low rpm combustion characteristics are better, but the proportion of friction power increases a lot faster. Looking at a dyno chart of a CBR600RR, the torque seems to pick up a lot at 3000, going to 30 lb-ft or ~45Nm by 4000rpm, and 75Nm/L is around what "Atkinson cycle" engines with a similar intake valve closing point pump out, which is a good sign. So maybe like 4000-7000 is a decently efficient range for applying heavy throttle and you could get away with cruising at 3000 efficiently. For other bikes maybe try to observe where the torque has a similar steep ascent, that probably indicates combustion efficiency picking up. I would guess that it scales mostly with the stroke, since bike engines tend to be designed with the highest possible rev limit and are given cams to suit, though obviously an FZR600 that's basically a detuned R6 probably will be efficient at a considerably lower rpm.

renault_megane_dci 01-18-2014 04:03 PM

A FZR600 as detuned as it is, is still with a very high peak torque rpm required for its 170 hp per litre (100hp variant) or 130 HP per litre in the 79hp version ...

The more I think about it, the more I believe peaky engines are better for bikes because it will be less prone to rear wheel lock on throttle closing.


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