I Was interested in the "milage modification" tread

[SuperG]

I like to ask the moderators not to close treads if possible, unless it harms the forum or its members.

It is a discussion forum after all? Isn't it?

It swayed out of topic but no harm was done.

 

About gaining miles per gallon on bikes,

 

Following guides from the hyper-miles car website does not really apply to bikes as much.

 

Over inflating tires will only temporarily work on cars, it make the car tire profile from flat to round reducing drag, once the middle wears equal to the rest it is back to flat surface and a good tire was prematurely wasted.

It does not work on bikes.

Reducing air drag would work but only so much can be removed before it hurts "function", such as carry bags, mirrors or anything that sticks out.

 

Upping drive gear ratio would be ideal but can not be done easy on a shaft driven bike. Going with a larger front or smaller rear chain driven sprockets does work. I've done it on my V-strom.

 

 

[bmurphypdx]

I see that thread about 5 threads down from yours. ??

[Twisties]

It's locked. It's locked because someone took it political and folks were about to notice and it would have gone ballistic. It irks me that various assertions must now stand unanswered. It irks me that one person, or maybe a small number, depending on your reading, ruined it for the likes of those that were still on topic.

 

I don't like that it's locked, but I fully support the moderator's decision to lock it. My guess, the moderator likely hated locking it as well.

 

The board has rules. We agree to them. One is no politics. Another is no publicly disputing the moderators. The original thread violated one, and this thread, however innocently, seems to violate another. It is my understanding that the moderating board likes to see what they call "self-moderation." and therefore I am suggesting that we, the members, let this thread die here and now.

 

If someone wants to bring up an aspect of fuel economy in a new thread, without the comments on board policy and reference to the prior thread, it is my guess the moderators would not be offended, but that is just a guess. PM them and ask if you are so minded.

[Ponch]

If the bike is well cared for and in a good state of tune, there's probably not a lot to be done to increase mileage dramatically. I suppose we could lessen the drag and weight, ride slower and more consistent, but how much will that net? It seems that the RT gets between 40-52mpg. That's a big range, but there's a lot of variables that go into it, not to mention measuring fuel mileage.

[David13]

My opinion is that there is not much that can be done.

Select your car, fuel efficient, or gas guzzler, then live with it.

On the motorcycle, stay under 1 liter. How much gas does a 1600 cc engine use? Too much for me.

As for over inflating tires, what does that do for the tire, and the ride? Nothing good, for very little savings in gas.

If you are concerned about rolling resistance on the tires get steel wheels, like the trains have.

But you won't like it when you hit a bump.

Staying under 75 mph also works for me (74mph) both for fuel efficiency and drivers license points system.

dc

 

 

[Quinn]

I wonder how much difference different tires would make. I'm thinking that harder, less grippy tires would have less rolling resistence. Also newer tires with a smaller flattened middle should help.

 

Probably less effect than taking a big ole bowel movement before riding has.

 

---

 

 

[SuperG]

True, harder tire with less contact with the road = less rolling resistance, but it also means less traction accelerating and braking.

 

Usually the inline bikes (K1600) are built for performance, and the dual overhead cam bikes like to rev to produce power and eat gas faster.

I was truly surprised when I got my RT that it got 50+ mpg riding in mild manner under 60 mph.

My 650 Vstorm got 50mpg with stock gearing and that was a 650 cc bike. After sprocket change -solo riding i regularly got 60+ mpg.

 

An other thing we have with the RT is that we are pushing a good amount of air. Wide topperware up front with built in mirrors does not help, cylinders sticking out is a drag too at high speed.

So for a 1200cc bike 570+ pounds, big windshield it is not bad at all. I think BMW did a great job with the RT as far as fuel usage.

 

[moshe_levy]

Regarding tires, I've driven a few high MPGs cars which come standard with LRR (low rolling resistance) tires. In general, the tradeoff to modest gains in mileage is a pretty hard compound which sacrifices grip, especially in the wet.

 

Quantifying the MPG gain is tough, but on my Prius board for example, most members who replace the standard LRR tires with more "run of the mill" all-seasons with much higher grip thresholds report an MPG drop of ~1MPG on the same cycle / commute. This is why almost nobody (on the board at least) replaces worn LRR tires with another set.

 

In a car, it's one thing, but I wouldn't want that sort of tradeoff on my motorcycle tires.

 

I don't remember the figures offhand, but I clearly remember in my 2004 RT's manual, that there were fuel economy figures given by the factory for a few given speeds. I remember pretty clearly that higher highway speeds had an exponentially devastating effect on MPGs.

 

This was proven to me last year, when I accompanied my friend, a new rider, on his first highway ride. Normally, my RT averages 40.5MPG, at best, because in general I commute with my cruise set to 79MPH.

 

My friend, being a newbie, was veru cautious on the highway and didn't break 60mph the whole day. It drove me crazy, but when I got home and checked the RT's computer, the MPGs were 52 for the 250 mile round trip. Quite a difference.

 

I wonder if my 2009 RT manual has these figures in there - need to check once I get home.

 

-MKL

[johnlt]

Moshe, the GS Adventure is even a better example of "dirty" aerodynamics and has a huge mpg impact. On my 06 GSA, I got 48 mpg around the Tucson area with average speeds <60 but on the interstate crossing Texas with average speeds of ~85, it dropped to 36 mpg. Those huge square panniers really produce drag.

[moshe_levy]

Mitch would be the best person to elaborate, but in addition to relatively poor aerodynamics, I'm wondering about what technological advancements the average fuel efficient automobile has (to serve the goal of increased MPGs) vs. motorcycles. Stands to reason that with regulations and fleet average MPG figures being a major concern to auto manufacturers - vs. not a concern at all to motorcycle manufacturers - that there are systems cars have (e.g., direct injection) that motorcycles do not and can benefit from. The question is whether motorcycle customers care, and more importantly whether they're willing to pay extra for these features. I'm wondering from a technological perspective what those features are (I'm sure there's more than just direct injection).

 

-MKL

[SuperG]

Im not sure what is holding back the motor cycle manufacturers to make truly fuel efficient bikes.

If my 1989 1.5 liter honda civic CRX-HF two seater car, hatch back with manual trans (had no ABS but I think it had A/C)could yield a true 40 city and 50mpg hwy miles (back in 1989).It was fun to drive too. It was 20+ years ago. My hybrid civic get ~40 mpg.

the 1989 civic was programmed multiport fuel injected- only sprayed fuel when on intake cycle. GM was still dicking around with throttle body injection and non sequential multiport injection.

 

Main stream motorcycles got fuel injection very late in the game. 2005 yamaha Fz1 (liter bike) inline 4 still used carbs.

Why have bikes fallen behind in technology?

Will I live the day of a main stream electric bike?

 

[GRB60]

There's a math error on the Motorrad site technical spec page.

5.2L/100km, when I redo the math, is equivalent to 45.1 miles per gallon. That is the spec BMW lists at 120km/hr, which is 74.4 MPH.

The site lists 65.3 MPG, which none of us have seen, I don't think.

The other listed spec, 4.1L per 100km @ constant 90km/hr is equivalent to 57.1 MPG at a constant 55.8 MPH. The site lists that one at 43.3MPG.

It just doesn't make sense that the bike would do 50% better at 74MPH than it does at 55.

=====

45.1 @ 74MPH sounds about right, so their usage seems reasonable even if their math isn't.

=====

My calculations assume they are using a US gallon.

[4wheeldog]

With bikes, performance sells a lot better than MPG. Technological upgrades (Fuel injection, ECU conrol, computer managed ignition) have to be paid for over fewer units than in cars or trucks. Tuning has always favored power over economy. (Think about all the add on "Chip" devices.....How many are slanted to mileage as apposed to increased performance?)

 

We get what the majority are willing to pay for. In some areas, they are not mutually exclusive......But when they are, for motorcycles, power is the priority.

[moshe_levy]

Im not sure what is holding back the motor cycle manufacturers to make truly fuel efficient bikes.

Why have bikes fallen behind in technology? Will I live the day of a main stream electric bike?

 

Two main drivers are regulation, and cost. Regulation because car manufacturers are employing advanced technology to raise corporate fleet MPG averages to comply with fuel economy regs. No such regs exist for bikes, meaning:

 

a) There is no reason to do it unless you show a cost / benefit that customers are willing to pay more for this technology, and....

 

b) The cost is spread over a far lower economy of scale than cars, meaning an exponentially higher affect on a bike's price than on a car's if, say, BMW added direct injection to its bikes as it has on its cars. Again, will customers pay for it?

 

Re electric, yes, you will see it. Battery technology is leaping forward at a fantastic rate. Smaller, lighter, longer lasting than ever. The Shorai thread has some more info on this (LIFEPO4 can pack 18AH worth of capacity in what lead acid chassis can usually fit 9-10AH, max - that's progress!). I am conducting a test of these as we speak.

 

The question again is one of market economics. Are enough people out there using bikes in such a way that electric makes sense for them to actually buy, or not? Several companies are dipping their toes into this market, and their fates will reveal the answer. See http://www.zeromotorcycles.com/ for one prominent example.

 

-MKL

[EffBee]

It's locked. It's locked because someone took it political and folks were about to notice and it would have gone ballistic. It irks me that various assertions must now stand unanswered. It irks me that one person, or maybe a small number, depending on your reading, ruined it for the likes of those that were still on topic.

 

I don't like that it's locked, but I fully support the moderator's decision to lock it. My guess, the moderator likely hated locking it as well.

 

The board has rules. We agree to them. One is no politics. Another is no publicly disputing the moderators. The original thread violated one, and this thread, however innocently, seems to violate another. It is my understanding that the moderating board likes to see what they call "self-moderation." and therefore I am suggesting that we, the members, let this thread die here and now.

 

If someone wants to bring up an aspect of fuel economy in a new thread, without the comments on board policy and reference to the prior thread, it is my guess the moderators would not be offended, but that is just a guess. PM them and ask if you are so minded.

 

A reasonable and pretty accurate assessment. Here's the sitch:

 

Someone takes a thread and makes a political comment, or tries to steer it in a political direction, it's going to get closed. However, does that mean that the discussion is closed? Of course not.

 

Open the same discussion anew. Include a bold-faced caveat in your first post that you want to discuss this topic and that people had better keep their dadburned political opinions out of it or it'll get closed like the last one. Don't name names. Most people know when it's them. And most people are here to get along. That's why we don't make a huge thing out of it. We just close it, send the offender a warning, and move on.

 

So re-light your topic. Keep it on track, and share/learn from the collective experience. It's called pre-emptive group moderation. And it need not involve any of the Mods. It's something we, as members, do among ourselves.

[SuperG]

awesome! That is exactly what I wanted to hear/read.

It is hard to tell when it gets "political enough/rule breaker".

Topics almost always sway from the OP's original question.

However it was good reading and good some information.

Example: it was very interesting to learn how gas price is broken down from crude oil -advertize -gov fees- and to the pump.

It had not much to do with "milage modification" , but it was interesting. The beauty of discussion forums.

Sorry for the sidetrack, please carry on

[DaveTheAffable]

Even in the engineering model (leaving politics and oil industry out TOTALLY), we have to remember that the customer (The motorcycle rider) drives the ROI (Return On Investment) for any particular change.

 

Let's say it costs the manufacturer X dollars in engineering, or direct costs, to make a motorcycle 6% more fuel efficient. How do they recover those costs? Increase the price of the motorcycle? Most (not all) riders are more interested in the bikes OVERALL performance and mileage, than minor percentage of gas mileage improvements. If the improvement doesn't increase units sold, there is little incentive for the manufacturer to pursue it.

 

Same is true for us as riders adding "Gas Saving" farkles to our motorcycles on our own. How much does it cost, how long to see ROI.

 

"Cost" may include money AND safety. An over inflated tire is less safe, and it wears unevenly, meaning it has to be replaced sooner.

[Joe Frickin' Friday]

Mitch would be the best person to elaborate, but in addition to relatively poor aerodynamics, I'm wondering about what technological advancements the average fuel efficient automobile has (to serve the goal of increased MPGs) vs. motorcycles. Stands to reason that with regulations and fleet average MPG figures being a major concern to auto manufacturers - vs. not a concern at all to motorcycle manufacturers - that there are systems cars have (e.g., direct injection) that motorcycles do not and can benefit from.

 

I can think of a few factors.

 

First, engine RPM. My car is a Nissan Maxima, with a 6-speed manual transmission. As performance-oriented as it is, it gets pretty good highway mileage (~30) because top gear gets the cruise RPM down to about 2500. Contrast this with my RT, which cruises at around 4500. High RPM results in increased mechanical friction from the engine, but also means reduced throttle, which results in higher pumping work requirement to suck air past that nearly-closed throttle plate. Look at how they get decent fuel economy from monster-engined vehicles like the Corvette: last time I looked, cruising RPM on a ‘Vette was something like 1750 RPM. But we motorcyclists want performance; we want to be able to roll on throttle without having to drop a couple of gears, and still be able to pick up speed in a hurry. So top gear is relatively low, and fuel economy is nowhere near what it could be.

 

Second, power-to-weight ratio. Look at the P/W ratio for your car; relatively speaking, your bike has a massively powerful engine. My RT? 110 hp, 780 pounds (w/rider), making 0.14 horsepower per pound. My Maxima? 255 hp, 3000 pounds (guessing), making 0.085 horsepower per pound. The difference is even more dramatic if you’re looking at econo-boxes like the Honda Civic. As described above, a bigger engine means that when you’re at cruise, you’re using a smaller percentage of rated power; you’re using a lot of extra fuel to drag these extra/bigger engine parts along for the ride, and the throttle plate is barely cracked open, resulting in high pumping losses. But we motorcyclists want performance, so the manufacturers give us monster engines.

 

Third, oil. My RT is running with 20W-50 oil in the crankcase; my car is running with 5W-30. At full operating temp, 50-weight oil is twice as viscous as 30-weight oil. But we motorcyclists want performance, so the manufacturers use smaller load-bearing surfaces to make the engine lighter/smaller, so they can cram even bigger engines into the bike and still end up with a manageable weight/size.

 

Fourth, EGR. Exhaust gas recirculation is a pollution control measure, but believe it or not, it can actually help with fuel economy. Diluting the incoming charge with exhaust gas means that for a given power output, you use a larger throttle opening, reducing pumping losses. The inert exhaust mass also absorbs some heat from the combustion event, resulting in lower peak combustion temperatures and therefore lower heat rejection to the cylinder walls, leaving more energy available for conversion to mechanical work during the expansion stroke. And the change in combustion chemistry and lower peak temperatures mean that you can use a higher compression ratio and/or more spark advance. For all of that though, EGR isn’t used at full load, so it doesn’t help with peak power output, just part-load efficiency. EGR adds cost and weight, and takes up space in a setting where space is at a premium. We motorcyclists want performance; when we’re shopping for a bike, we’re looking at the peak horsepower numbers and 0-60 times, not cruise MPG. You won’t see it on bikes until it’s mandated and/or motorcyclists start paying attention to fuel economy when they’re in the market for a new ride.

 

Finally, aerodynamics, probably the biggest factor of all. As has already been pointed out, bikes are “dirty.” Picture an RT or GS – or worse, a Goldwing – with a rider seated on it. There are all kinds of sharp edges and obstructions, a huge frontal area, and a Lexan barn door (in a nearly vertical orientation) leading the charge. To understand the importance of aerodynamics, take a few minutes to watch

from an engineering professor. With the right aerodynamic shape, you can lower (or raise) the aerodynamic drag of an object by a factor of 10. That’s huge. Compare the shape of your bike to a car: once you get past the grille, you’ve got smooth body panels, rounded edges, a windshield laid back to a very shallow angle (and a rear window to match), and a rounded back end. The Prius may be a butt-ugly car, but it’s shaped that way for a reason. But we motorcyclists like the open air, and we like being on the bike instead of in it: we don’t want a cage around us (even a transparent one), and we don’t want to ride along with our butts a few inches off of the pavement. If you’re willing to accept certain compromises to improve the aerodynamics, you can hit 186 MPH with just 44 horsepower; compare this with the Hayabusa, which requires approximately four times as much power for this speed.

 

So why aren't bikes getting better fuel economy? In a nutshell, it's because the people buying them have other priorities.

[moshe_levy]

Mitch-

 

All good, but please clarify the RPM example. IIRC you have a late model RT, and I have a 2009 myself. In 6th at 80mph, which is cruising speed here at rush hour, the motor is barely turning 4,000rpm. I can't imagine you're cruising in the RT at 4,500 rpm in 6th, are you? Or did you mean lower highway speeds in 5th at 4,500 rpm?

 

-MKL

 

PS - Kammback is a beautiful thing.

[NonComp]

All good, but please clarify the RPM example. IIRC you have a late model RT, and I have a 2009 myself. In 6th at 80mph, which is cruising speed here at rush hour, the motor is barely turning 4,000rpm. I can't imagine you're cruising in the RT at 4,500 rpm in 6th, are you? Or did you mean lower highway speeds in 5th at 4,500 rpm?

Most oilheads don't have a sixth gear

[moshe_levy]

Mine did (2004 RT).

 

-MKL

[Joe Frickin' Friday]

All good, but please clarify the RPM example. IIRC you have a late model RT, and I have a 2009 myself. In 6th at 80mph, which is cruising speed here at rush hour, the motor is barely turning 4,000rpm. I can't imagine you're cruising in the RT at 4,500 rpm in 6th, are you? Or did you mean lower highway speeds in 5th at 4,500 rpm?

 

Sorry, it's been a long winter here. '09 R1200RT here; don't recall the exact RPM, but it's certainly over 4000 in 6th at 80. And yes, my 1100RT was even higher cruise RPM. Point is, it's quite a bit higher than most cars.

[James Clark]

You want a high-mileage bike? Convince BMW to use a direct-drive gearbox . . .

 

 

again.

[moshe_levy]

Mitch-

 

That's interesting. I haven't ridden all winter so maybe my memory's off, but I don't remember her revving that high at 80mph...

 

-MKL

[OlGeezer]

Mitch-

 

That's interesting. I haven't ridden all winter so maybe my memory's off, but I don't remember her revving that high at 80mph...

 

-MKL

 

Mine turns 4000 RPM at an indicated 80 MPH, so that's actually more like 75 MPH. Extrapolating, that would be about 4,300 at an actual 80 MPH.

[Twisties]

Mitch-

 

That's interesting. I haven't ridden all winter so maybe my memory's off, but I don't remember her revving that high at 80mph...

 

-MKL

 

4200 = 80 mph (indicated)

 

 

Oh, and it's officially touring season in the Rocky Mountains. Saw a couple on a pair of 'wings and a guy on an HD passing through on I-80. She didn't look any bigger than Sharon on that 'wing. A tiny mite. 50's, full sun, and dry today.

[Ponch]

All good, but please clarify the RPM example. IIRC you have a late model RT, and I have a 2009 myself. In 6th at 80mph, which is cruising speed here at rush hour, the motor is barely turning 4,000rpm. I can't imagine you're cruising in the RT at 4,500 rpm in 6th, are you? Or did you mean lower highway speeds in 5th at 4,500 rpm?

 

Sorry, it's been a long winter here. '09 R1200RT here; don't recall the exact RPM, but it's certainly over 4000 in 6th at 80. And yes, my 1100RT was even higher cruise RPM. Point is, it's quite a bit higher than most cars.

 

My 2001 Jetta hits around 4000 rpm at 80. It needs a 6th gear bad.

 

 

[moshe_levy]

6th, eh? A few of the major automotive tranny companies are working on NINE speed automatics. They're be out within a year, is my guess. Anything to eek out a few more MPGs....

 

-MKL

[Peter Parts]

Interesting discussion. What can be added to insights from Joe Frickin Friday and others?

 

1. Everything on a bike is subject to very painful trade-offs of weight, complexity, maintenance effort, size, etc. not found in cars as painfully. So adding fuel-saving mechanisms is hard.

 

2. Yes, lousy air resistance. But bikes need air cooling as a minimum frontal area (as well as the trade-offs above); but that reduces the need for radiators, fans, etc.

 

3. Rich fueling helps sporty engines have a more flexible power band leading to less shifting. So riders don't want too narrow a practical power band.

 

4. Long debates about the BMW boxers being lean. Yes, kind of forced to aim for lean running but fuel-piggish at the same time due to constraints on how the cylinders are designed. Yes, both.

 

5. Boxers have inefficient drive trains compared to chain-driven bikes. And then there is the idiotic, two-universal coupling Paralever....

 

6. Can't go adding width to a horizontal boxer but, for a laugh, imagine a boxer laid out any other way. Great concept in most other respects. Love 'em.

 

Ben

back home from 84F in West Palm Beach

 

 

[tallman]

I don't know, never had the GT up to 80 before...

[Ponch]

I don't know, never had the GT up to 80 before...

 

I am sorry....

[OlGeezer]

I don't know, never had the GT up to 80 before...

Neither have I. That's why I had to extrapolate.

[tallman]

I don't know, never had the GT up to 80 before...

Neither have I. That's why I had to extrapolate.

 

 

I barely have enough polate.

Where did you find the extra?