Thoughts about Gas Mileage (long)

[V7Goose]

When I am riding solo with no one to talk with, my brain starts to limber up and tries to escape. Sometimes all that thinking can be dangerous!

 

On my way home from Don's this week it seemed to me I was getting particularly poor mileage, so I was doing a lot of thinking about it and thought I'd share with y'all. This is gonna be long - I had 3,000 miles to think on this trip!

 

 

 

Things that affect fuel mileage, in no particular order (some more obvious than others):

1. How full you fill your tank*
   
2. Tire pressure
   
3. Tire size, style, and composition
   
4. Engine condition
   
5. Primary and secondary electrical circuits
   
6. Temperature of the gas when you fill up
   
7. Temperature of the air
   
8. Humidity
   
9. Altitude and barometric pressure
   
10. Gasohol (but NOT octane)
    
11. Riding style, location, and terrain
    
12. SPEED
    
13. Winds
    
14. Add-on miracle gadgets from late night TV commercials
    
15. (I am sure I missed something here)
    

Number 1 doesn't really change fuel mileage, of course, but it sure can throw off your calculation, especially with a small tank. For example, filling up with 5 gallons of gas after going 180 miles will give you 36 MPG (close to my average). But if you happen to squeeze 5.29 gallons of gas into the same tank, your calculated mileage would only be 34 MPG, and if you stop just a little short at only 4.73 gallons, you would be "enjoying" 38 MPG. So less than 1/3 of a gallon difference in our fill-ups makes more than a 5% change in the calculated MPG. Quite a significant change.

 

The trick, of course, is to ensure you fill that tank to exactly the same level every time, and that is not easy. And if you have not vented the filler neck it is REALLY hard if you are trying to get it as full as you can to go longer between stops. I know when I am dinking around with the hose at the top of the tank trying to get the amount to stop exactly on even digits (such as $18.11 or $18.22, etc.) that I can easily put in more than 1/3 of a gallon more than where I already thought was a full tank. That is why I think it is so important to check mileage all the time if you are going to report it or compare with others - just a tank or two is not accurate to me.

 

Tires - they affect mileage by how hard they are to roll. But I really have no idea how big a difference they make in actual calculated MPG, so I won't dwell on them here. Simply said, the more air in them, the harder they are, and the easier they are to roll. In addition, different rubber compounds and tire construction can change the way they flex and make rolling harder or easier. Even so, I tend to dismiss tires as not being a significant part of the MPG equation, but I'd like to hear from anyone who has more information and thinks they are significant.

 

Engine condition is a biggie. If it is not running right for any reason, you get very bad mileage. If you engine is wearing out and your compression is dropping, it may still run fine, but your mileage will suffer a lot. Miss-adjusted or burned valves will kill you (figuratively speaking). Timing being off, fouled plugs, dirty carbs, etc. are all bad (note that the timing on the RSV is not adjustable).

 

The electrical system on the bike can have a noticeable affect, but problems are not common. The primary and secondary circuits refer to the ignition circuit before and after the coils. In short, if you have a weak spark, you may not be getting full and consistent ignition of the fuel, thus causing poor mileage.

 

Temperature of the fuel when you fill up is a big impact, but nothing you can control - just know that it can change the actual MPG by around 5%. Everything expands with heat, and fuel pumps only have to be accurate when the fuel is about 65 degrees (going from memory here). In the summer the fuel is warmer, so 1 gallon takes up more space. That means when the pump says it gave you 1 gallon, you really got less! It does not help filling up in the mornings, since the air temperature has little to do with the temperature of the fuel in the underground tanks. But the WORST time to fill up is in the summer during or right after a tanker has delivered fuel, since the fuel in the tanker is going to be a lot warmer than the fuel that has been underground for a day.

 

Temperature and humidity affect the fuel mixture and combustion qualities of the mixture. Cold air is more dense; therefore, you get a leaner mix. Water compresses much less than air, so it not only affects the mixture, but the way it burns too. But frankly I do not know how significant these affects actually are. Probably not much.

 

Air at altitude is thinner, so you run richer (less air to the same amount of gas) and get worse fuel mileage. The change can be significant in both MPG and power, but I don't know the percentages off hand. You may not know that changing barometric pressure is just like changing altitude. A storm coming in gives you the same affect as going up in altitude.

 

Gasohol at any % is simply a curse from the bureaucrats! Alcohol has less energy than an equal volume of gasoline, so mixing any of it in your gas makes the same volume less powerful and you will burn more to do the same work. Curses!!! Octane, however, has no impact. Do not waste your money putting in any higher octane than your engine needs to not detonate (knock or ping). The RSV is specifically built to run on regular.

 

Your individual riding style, including how much weight is on your bike, stop and go, steady speeds, hills, etc. all have a huge effect on your MPG. The faster you accelerate, the more you have to use your brakes, the more weight you carry all take a big toll on your mileage. Maybe hills don't have that much of an impact, since you gain back on the downhill side what you lost going up.

 

I put speed and wind near the bottom of this list for a reason - they are quite similar and have the single biggest impact on MPG beyond something being wrong with your bike. I know for a fact that my Ventures and my riding style generally average 36.5 MPG combining around town riding and most highway speeds. But if I burn a tank at an indicated 80 MPH (actual 73 MPH) I will loose 3 - 5 miles per gallon. Conversely, just keeping it under 50 MPH for a tank, like riding the twisties in the Ozarks, will easily add 5 miles per gallon. The biggest part of that change is wind drag on the bike. So a 20 MPH change in average speed can swing the mileage by close to 10 MPG! Now realize that riding into a 20 MPH wind is even worse, since the impact of wind resistance is not a straight line - more logarithmic, meaning each additional mile per hour of speed has much more drag the one before it. Quartering headwinds are almost as bad. Tail winds, of course, are wonderful things.

 

The last thing I am going to mention here are the miracle cures that you can find in any auto parts store, catalog, and late night TV commercials. EVERY ONE OF THEM IS GARBAGE!!! The only way any of those things can improve your gas mileage is to lighten your weight by taking away your money. Nuff said.

 

I don't know if any of that will be of value to anyone (and I'm sure there is liable to be a lot of disagreement somewhere), but what the hey - thought I'd type it all in anyway. Ride safe all, and I hope your gas prices stay low!

Goose

[hipshot]

very informative "meanderings", Goose! thanks for all the info.

 

 

 

now i know why Don made you a moderator!

you can't be allowed to have too much time to think about "abstract" ideas.

i surely do hope though, that someone who knows, will corroborate or correct your observations.

just jt

[GigaWhiskey]

You had a long ride to think about all of that. I guess it was all pent up inside you and you had to get it all out somehow. Hence, why it was long.

 

Good post and an interesting read! Had some things I did not consider or consider enough.

[Eck]

Not bad Goose,

Reading your looooong post...I was cruising really well while I was in the laid back position in my cumfy padded chair and after a few calculations, I found I got about 25 words to the minute,,,,that was until I made an adjustment where I sat up, but then because of the extra height, I found I had more wind shear, which cut me back to about 20 words per minute. Being uncomfortable in this straight up position, I slowly laid "way back" with both legs extended fully out in front of me, and man what a difference...

got mer to about 28 words per minute..

Im n cruise right now..will check in again later....

[mbrood]

Back in 1970, my mom got a "deal" on a fairly new 1968 Grand Prix... what a "deal". As a senior in high school, I was EVER so tickled. That thing would pin you to the seat and was just TOO much fun... until you looked at the gas gauge. Yes, you COULD punch the pedal and watch the gas gauge go lower although you REALLY had no business watching the gauge... telephone poles started sliding by awful fast. A friend tried to tell me the gas was moving to the back of the tank, making the gauge read lower... except it never "came back"... you could empty a tank real quick.

 

I put a vacuum gauge below the dash and if you treated it with "kindness" and kept that nasty vacuum gauge in reasonable limits, you could get "reasonable gas mileage". Open up the four barrel and all bets were off... Judicious use of that throttle REALLY made a difference on a young kid's available money! But every once in a while...

[V7Goose]

Not bad Goose,

 

Reading your looooong post...I was cruising really well while I was in the laid back position in my cumfy padded chair and after a few calculations, I found I got about 25 words to the minute,,,,that was until I made an adjustment where I sat up, but then because of the extra height, I found I had more wind shear, which cut me back to about 20 words per minute. Being uncomfortable in this straight up position, I slowly laid "way back" with both legs extended fully out in front of me, and man what a difference...

got mer to about 28 words per minute..

 

Im n cruise right now..will check in again later....

Hey, I warned ya it was long, TWICE! So don't come whining to me about that. I find it quite interesting that your words per minute goes down when you sit more upright - mine usually goes up! But I am quite concerned with your productivity - do you have to sound out a lot of words? If it takes you two to three minutes to read this reply, I'm not sure how you got through my original post in less than a day! :rotf:

Read on friend, but you might want to save some time by not looking at the quoted parts of the replies - after all, you already sounded all them out!

[Redneck]

Goose I agree with most of you thoughts on the subject. A worn engine unless it has a major loss of compression will make more power from the same fuel thus get better fuel mileage as long as the compression loss is not through the valves. the reason for that is internal drag of a worn engine is less than a new engine. Roughly 3/4 of the power the engine makes is use up internally by friction less internal friction means more of the power goes to the drive train. The engine in the rsv makes roughly 400 total horse power but uses 300 of it to get the 98 usable horse power out of it.

[BigShell]

Pushin' air really does take it's toll on mileage. A few weeks ago I took off my tall and wide Clearview and put on a cut down (2'' shorter) stock windshield. With the hot weather, I've also opened the lower wind deflectors. Looks like I've gained about 2 mpg by pushing aside less air.

[GeorgeS]

OK, figure the gallons for the 3000 mile trip, Total that you burned.

 

Now assume, you got lets say 4 MPG better,

 

How much Less Gas would you have burned?

 

How much less money would that have cost ?

 

Now, ask yourself, is it really worth worrying about, within the larger scheme of things ???

 

Especially when you consider that we only get to live one life, and we are

some of the lucky few that get to ride motorcycles !!! ( wherever we happen to ride to )

 

Question? Did you have a good time on this trip ???

 

If you had spent the day playing Golf of some similiar sport, would you have spent

any less money ??

 

In comparison to all the other costs of owneing and operating a Motorcycle, is the cost of fuel, really that big a deal ????

 

I went out today and rode around " Aimlessley " for 3 hours, I wasted about $12.00 worth of gas, But you know what, I enjoyed the day !!! It was money Well Spent !!!

 

And I don't care what the Envirenmentalist Wacko's have to say about burning to much of the stuff!!!

[RoadKill]

I ride, I buy gas, I ride. Only time I figure mileage is if somebody asks me. I found the most savings on gas expense I get is when I don't go anywhere

Hence, I have chosen to not stress my mind whith fuel costs. Gotta go to work and No way I'm not going to ride. I'll cut back on food first:2133:

[V7Goose]

OK, figure the gallons for the 3000 mile trip, Total that you burned.

Now assume, you got lets say 4 MPG better,

How much Less Gas would you have burned?

How much less money would that have cost ?

Now, ask yourself, is it really worth worrying about, within the larger scheme of things ???

Especially when you consider that we only get to live one life, and we are

some of the lucky few that get to ride motorcycles !!! ( wherever we happen to ride to )

Question? Did you have a good time on this trip ???

If you had spent the day playing Golf of some similiar sport, would you have spent

any less money ??

In comparison to all the other costs of owneing and operating a Motorcycle, is the cost of fuel, really that big a deal ????

 

I went out today and rode around " Aimlessley " for 3 hours, I wasted about $12.00 worth of gas, But you know what, I enjoyed the day !!! It was money Well Spent !!!

 

And I don't care what the Envirenmentalist Wacko's have to say about burning to much of the stuff!!!

Well GeorgeS, I understand what you are saying, but then again, I don't. I got what I got today because I don't needlessly waste stuff I don't have to, whether it be gas, water, food, money, etc. If I can save money without materially impacting my experience, why wouldn't I??

 

To answer your question, at 36MPG, the trip would have cost roughly $331 in gas alone; at 40MPG, that cost is $298. If I was walking along and found $33 lying on the ground, I'd pick it up, wouldn't you?

 

And yes, I too often ride around aimlessly just to enjoy the ride, but if I can do it for $11.50 instead of $12, I will.

 

BUT, the bigger point of my post, besides maybe giving folks some ideas about how to save gas if they wanted to, was to help people understand WHY their gas mileage might be different from one day to the next, or different from someone else when comparing numbers.

Goose

[BigD]

You should have gone another 2000 miles, you could have came up with a solution for world peace.

[GeorgeS]

Did you see the posting by " Squeez " in Germany the other day ?

 

He said the Oil Barrons, have their Office's in Hamburg, their Office buildings next to each other, and that can set the price with hand signals just like the folks do on the Stock Exchange floor. There is NO Legal Record of this Price Fixing.

 

Oh well, I have noted over the years, that some things I buy have gotten more expensive. However other things are much Cheaper.

 

The first Color TV I bought, cost me about $500 back in 1972. Adjusted for Inflation, that about $5000.00 in todays money. ( how much a color TV cost today ? )

 

Back in 1974 I bought a small New car for $2400.00, thats about $25,000.00 in todays money, and today I can buy a same size car for $13,500 , today. ( and its a better car ) I can get that car for Half as many pay checks today, as I paid back in 74.

 

So I have the difference between 13.5K and 25K to use to buy gas.

 

I'm all for Alternative Energy source's !! But for the next 20 to 30 years they can only supply 20 to 30 precent of world needs, At Best. IF, they are developed.

Question is, will they be developed ?

 

I doubt the oil Barrons in Hamburg are going to let that happen.

[Squeeze]

...

 

I doubt the oil Barrons in Hamburg are going to let that happen.

 

They will George ... they WILL ... THEY ARE ...

 

 

Alternative Energies are a huge Factor in german and europe's Economy and rising straight up every Year.

 

Shell build a factory for electrical Solar Pannels 5 Years ago, it was the biggest Factory on the Planet at that Time. BP entered this Business a Year or two later but with much more Money, they didn't even build a Plant, they just bought Production built by their Specs in Factories all over the World and labeled them. Recently Wurth has bought a big Area in a 'Future Technology Business Park' and the Plant is about to begin Production. With the warming Climate we're devleop here, this will be a big Part of our energetic Future.

 

But ....

 

In Germany we have drastic Laws about building your own Power Plant on your Roof. Up to 30 Kilowatt peak Production, nobody can claim anything against your Decision, only Exception goes for Buildings with historic Backgrounds. Not even the Power Company which has to buy your Power from you, can hold anything against your move. No Neighbors to deal with, no Bureaucracy, nothing. You just inform the Power Company about your Plant and call them to seal the Ticker. The Price is set by Law, and guaranteed for 20 Years from beginning of feeding into the Powernet. And the Price is high. Around twice as much as you pay for each kwh out of the Net. You can built a big a Field of Paneels just with a small Excel Sheet and your good Name. There's a Bank(owned by the Fed) which gives you a Lot of Money (50,000 Euros each Person per Year) for financing such Investments at cheap Interest.

 

Now, guess who's paying the Difference between Solar Price sold Energy and standard Energy bought ??

 

 

Not the Power Companies, not the Government, not the Taxpayer ...

 

 

 

NO ....

 

 

The Consumer does it, with his hard earned and well and more well taxed Money, which is left after more Taxes. Nobody else ... Well, another rip off i guess ...

[GeorgeS]

I'm with you on all that. I'm all for " Alternative Energy". However, At best it can only replace about 20 precent of total World Usage. Electric cars, Solar, whatever sombody can think of, but about 20 percent is the limit.

 

UNLESS, there are some New Breakthru's in Physic's !!!

Many people around the world are working on these things, they are comeing, but will take time.

 

That number ( 20 percent ) comes from Holland, where they have taken it the maximum, and have done 20 percent replacement of Oil products.

 

And your right, everything is eventually paid for by the consumer !! I agree with you on that one.

 

I have been hearing there is a company in Calif. that has made a big breakthru in Solar Cells, but not on the market as yet.

 

Another Point, concerning Corn Ethenol. If farmers were allowed to grow Hemp, instead of Corn, to make the Fuel. You can get almost 10 times the tonnage per acre ( or hectar ) of biomass to turn into fuel !!! Hmmmm ???

Maby sombody should think about that one. Interesting ???

 

One other item: We are not allowed to build any New Nuclear Plants in the U.S. I wonder why?

[GigaWhiskey]

UNLESS, there are some New Breakthru's in Physic's !!!

 

They got their eyes on the mining the moon for Helium 3.

 

http://www.space.com/scienceastronomy/helium3_000630.html

 

May not cure the fuel for vehicle issue but this should replace the nuclear reactors as an option.

 

Personally, I hope they leave the moon alone. If they mess it up, we all dead.

 

http://wiki.answers.com/Q/What_would_Earth_be_like_without_a_moon

[FuzzyRSTD]

Not bad Goose,

 

Reading your looooong post...I was cruising really well while I was in the laid back position in my cumfy padded chair and after a few calculations, I found I got about 25 words to the minute,,,,that was until I made an adjustment where I sat up, but then because of the extra height, I found I had more wind shear, which cut me back to about 20 words per minute. Being uncomfortable in this straight up position, I slowly laid "way back" with both legs extended fully out in front of me, and man what a difference...

got mer to about 28 words per minute..

 

Im n cruise right now..will check in again later....

Thats funny, really funny, I don't care who you are, thats funny...:rotf::rotf::rotf: I injoyed the read Goose. I too had not given that much thought to mpg, but man how I love too ride and read this forum.

[FuzzyRSTD]

Well GeorgeS, I understand what you are saying, but then again, I don't. I got what I got today because I don't needlessly waste stuff I don't have to, whether it be gas, water, food, money, etc. If I can save money without materially impacting my experience, why wouldn't I??

 

To answer your question, at 36MPG, the trip would have cost roughly $331 in gas alone; at 40MPG, that cost is $298. If I was walking along and found $33 lying on the ground, I'd pick it up, wouldn't you?

 

And yes, I too often ride around aimlessly just to enjoy the ride, but if I can do it for $11.50 instead of $12, I will.

 

BUT, the bigger point of my post, besides maybe giving folks some ideas about how to save gas if they wanted to, was to help people understand WHY their gas mileage might be different from one day to the next, or different from someone else when comparing numbers.

Goose

Thanks Goose.............

[bisquit]

Living on the Gulf coast I often have to fight 25 to 30 mph crosswinds. With my throttle loked down, if I pass an 18 wheeler or even an overpass, anything that blocks the winde my speed will instantly jump 10 to 15 mph.Yeah buddy, wind drag makes a big,big difference..........Don