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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.


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