Gas mileage!

Everything in-between the gas cap and the carbs. Also how the engine inhales.
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Turbojoe
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Gas mileage!

Postby Turbojoe » Sun May 27, 2012 12:38 pm

I've been using an app for my Android phone called "Fuel Log" since I bought my bike back in early May of 2011. I liked it so much I paid the buck or three extra for the full version so I can track everything related to owning the bike. Gas mileage, parts costs, maintenance intervals etc etc etc.

In looking at the gas mileage over the course of the year I see exactly the opposite of what I'd expect. In the colder months where I'd expect the best mileage due to the cooler more dense air I see a best of 46mpg and an average of 43mpg. The hotter it gets the better my mileage gets. Now that we're into summer and 100+ degree days I've seen a best of 54.6mpg and an average of 53mpg. That's almost a 20% difference in mileage!

I've ridden the bike to work every day since I bought it usually on the same route unless traffic causes me to look for a different route. Tire pressures, chain lube and inspect are done every weekend. Every 3,000 miles oil change, spark plug replacement (I scored a 12 pack of plugs for a great price), carb synch check, air filter check and clean as well as tire and chain inspect are also done. I add Sea Foam to the tank every third fill up. As you can see the bike is kept in optimum tune and there is little change in riding patterns so it all comes down to temperature change. I know many will get better mileage but between my fat ass and the extra 20 pounds or so that I normally carry in the saddle bags she's hauling around about 270 pounds so that's going to really hurt what might be possible with a smaller and lighter rider.

Just wondering if others have seen the same mileage changes related to temperature that I do. After spending almost 30 years in the automotive industry dealing with fuel systems what I'm seeing is backwards from what should happen. Maybe this engine just prefers high inlet temps? Here in the Phoenix area we get temp ranges from the low 30s to 110+ so we see it all.

Joe
The nonsensical ravings of a lunatic mind.....

2004 Vulcan 500

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Triangles
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Re: Gas mileage!

Postby Triangles » Sun May 27, 2012 9:36 pm

your results are typical, I've heard two theories I'll agree are plausible explanations.
1) colder dense air results in more drag so it takes more to move the bike thru the thicker air.
2) winter formula gasoline is less energy dense. I have no idea if this is tru but I've read it multiple places.

IIRC i'm lucky to get much above 50mpg in winter and usually get 55-57mpg summer. I've got new tires and new gearing so I guess that's all out the window. I'll see what I get.
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Turbojoe
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Re: Gas mileage!

Postby Turbojoe » Sun May 27, 2012 10:14 pm

I'm not certain about it but I've been wondering if there are now season specific gas blends they aren't saying a lot about. That would help explain what I'm experiencing. In the last 10 years I put less than 20,000 miles on my car so didn't really notice seasonal mileage changes. My previous job supplied an E-350 van that I kept at home and seldom drove the car. The van got 9mpg on a good day and they paid for gas so I didn't pay a lot of attention to gas mileage.

Joe
The nonsensical ravings of a lunatic mind.....

2004 Vulcan 500

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Turbojoe
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Re: Gas mileage!

Postby Turbojoe » Thu Jun 07, 2012 7:29 pm

Well it just keeps getting better. Several tenths of a MPG increase at each fill up but today I filled up and got 59.40 MPG!!!!! Same tank fill level. Same riding route for the last month or so. If I can hit 60 MPG all will be right with the universe and I won't expect anything else from the bike. Getting caught at a few less traffic lights could make the difference. I can just imagine what a 150 pound rider could get for mileage from my bike. Yet another reason to get back on and STAY WITH my diet! :mrgreen:

Joe
The nonsensical ravings of a lunatic mind.....

2004 Vulcan 500

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Triangles
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Re: Gas mileage!

Postby Triangles » Fri Jun 08, 2012 12:08 pm

I managed to eek out 61.9 mpg last summer being mostly stuck behind a slow semi going 50-60mph on a two lane road for for about 2.5 hours. and that was with my 200+ lbs and about an extra 50 lbs of gear. My last tank I got just over 50 but I think that's because I wasn't able to ride for a while and it still had stale December 2011 gas in it. I should be due for another fill-up next week so I should get a better idea of what my mileage is with the new 17/38 final drive gearing.
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Turbojoe
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Re: Gas mileage!

Postby Turbojoe » Fri Jun 08, 2012 6:44 pm

I'd sure like to know what to attribute my mileage increase to. I'm not complaining in the least but what's happening for me is counter intuitive. Most (including me) would expect mileage to drop in high heat conditions. I still get a smile on my face each time I fill up. One of these days I'll drive the car to work just to let it get a few miles further out than the grocery store. I'm sure it feels neglected. It hasn't been driven to work in over a year!

Joe
The nonsensical ravings of a lunatic mind.....

2004 Vulcan 500

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Triangles
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Re: Gas mileage!

Postby Triangles » Sun Jun 10, 2012 4:20 pm

I always thought it was a combination of winter formula vs summer formula gas (don't know if that's applicable to your location though) and the fact that hot air is less dense than than cold air. So warm are would offer less resistance. Also drag increases exponentially with speed and i usually ride at higher speed on the expressway. From that point of view it makes perfect sense that fuel economy goes up when it's warm. How that logic applies to your situation of warm to hotter than the surface of the sun, I don't know.
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Turbojoe
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Re: Gas mileage!

Postby Turbojoe » Tue Jun 12, 2012 7:46 pm

At the speeds I've been riding I doubt air density will have much if any affect on wind resistance. Engine performance yes but it should be just the opposite. Hot, less dense air should wreak havoc on mileage but in my case no. It has to be a seasonal fuel formulation change. I'll fill up tomorrow and see what I get this time. It's been kinda hot lately so I'm expecting some great MPG numbers!

Joe
The nonsensical ravings of a lunatic mind.....

2004 Vulcan 500

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Turbojoe
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Re: Gas mileage!

Postby Turbojoe » Fri Jun 15, 2012 6:48 pm

I finally did it! Broke the 60 mpg barrier! I filled up day before yesterday and got a respectable 58.54mpg but was still short of the hoped for 60 mpg. Filled up today and got 61.24!!! It was 111 degrees yesterday but only 104 today. I wish I knew whether it was temperature or fuel formulation that was responsible for my mileage increase. For now I'll just enjoy the big numbers I'm seeing.

I don't think I've had any vehicle I've been as completely pleased with as I am with my Vulcan. Had her just over 13 months and STILL haven't driven the car to work once. It's a grocery getter in the truest sense. That's the only time I drive it is when I need more food than I can carry in the saddle bags and my back pack..... :D

Joe
The nonsensical ravings of a lunatic mind.....

2004 Vulcan 500

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Triangles
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Re: Gas mileage!

Postby Triangles » Fri Jun 15, 2012 10:59 pm

good to hear! I've gotten another tank under my belt with the new gearing. My gas mileage is pretty much the same as it was last summer. However with the smoother lower RPMs on the highway, my hand seems to have a mind of it's own and is twisting the throttle more. Later this summer when I find time to take some lazy slow 2 lane road trips I would expect to be pushing the 60mpg barrier again. We'll see if I can eek out 65mpg if I can just keep my hand from twisting the throttle so much :D
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burkbuilds
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Re: Gas mileage!

Postby burkbuilds » Thu Jun 28, 2012 8:13 pm

When I was running mostly highway miles I usually got about 59 - 60 mpg's at around 70 mph in the Warm months, but like you, I also noticed that my mileage dropped off into the mid to low 50's in the Winter. I also noticed the same drop if I had to buy gas with ethanol in it. When I fill up around home, I can still find several stations with pure gas, but when I go to Atlanta, I have to fill up on gas blended with ethanol and the bike was really hard to start if it was cold and my gas mileage dropped about 5-6 mpgs. Therefore, I think you might be onto something when you hypothesize that Winter blends of fuel are causing your gas mileage to suffer. Either that or the 111 degree temps out there are causing heat to rise up off the pavement and lift your bike up like a hot air balloon making it lighter and more fuel efficient. :)

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Turbojoe
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Re: Gas mileage!

Postby Turbojoe » Thu Jun 28, 2012 8:59 pm

burkbuilds wrote:Either that or the 111 degree temps out there are causing heat to rise up off the pavement and lift your bike up like a hot air balloon making it lighter and more fuel efficient. :)


Laughed my butt off at that one! :lol:

I wish I could find "pure gas" around here but it's all ethanol diluted. I wonder if they change that dilution in the summer though. Keep in mind I'm NOT complaining. Just puzzled is all. My last fill up was yet another 61.24mpg exactly like my last high reading. If I can just keep it in the mid 50's I'll be ecstatic. The low 60's are just icing on the cake. My PT Cruiser gets about 20 mpg in town. 29 mpg on long drives. It's crazy hot here but even a bad day riding is better than a good day driving. It's even better when you get 2-3 times the mpg. I STILL haven't driven the car to work since May 2011.....

Joe
The nonsensical ravings of a lunatic mind.....

2004 Vulcan 500

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AKrider
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Re: Gas mileage!

Postby AKrider » Sat Jul 14, 2012 6:56 am

When I first got Rosebud (93 EN 500A) I was seeing around 38 to 41 mpg, then I figured out there was a 6th gear and mpg went up to around 44-45. I checked a couple of weeks ago after reading this and saw 51 mpg so I did a little mpg test, parked in the same spot every fill up, drove the same route to work, filled to the same edge of the filler neck with the bars turned the same way each time and for 276.7 miles I used exactly 5 gallons of gas for a total mpg of 55.3!

I think you guys are spot on with your reasoning and probably what you are seeing is mostly from the seasonal change in blends, for me well Rosebud had not been ridden much before I got her, and I've lost about 50 pounds since I got her too. Regular riding and maintenance are good for any bike (and rider).
We are what we repeatedly do, excellence is a habit.

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Turbojoe
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Re: Gas mileage!

Postby Turbojoe » Sat Nov 17, 2012 6:40 pm

Well here we go. Cooler temps are finally upon us here in Arizona and my mileage is dropping again. Makes no sense whatsoever for it to drop when its cooler but it does. With the temps now in the low 70's during the day and in the low 50's when I ride home at 1:00 AM my mileage has dropped about 5 mpg and I expect it to drop further when it gets colder. Last fill up was 56.4. I've gotten a best of 61.2 during 110+ degree heat. If I can keep it over 50mpg through the winter I'll still be happy. Just doesn't make sense why mileage drops on the bike but increases on the car. :?

Joe
The nonsensical ravings of a lunatic mind.....

2004 Vulcan 500

Ray
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Re: Gas mileage!

Postby Ray » Wed Dec 17, 2014 9:26 am

My understanding of gas mileage is that liquid gasoline does not burn. Only the vapors burn. As temperatures get lower, the vaporization rate drops, and so fuel mileage drops with it. Some people put gasoline warmers on their machines so that the effect isn't as noticable in cold temps. The icy air doesn't effect the gas too much if the gas itself has some heat in it to release which takes a vaporizing effect with it.

Which brings up a question. There are tons of videos on you tube showing cars and even a few motorcycles running purely on dry vapors. Has anybody attempted to route some of the tank vapors in to the intake air for a slightly richer fuel blend, which would result in better power at high end? Dry vapors burn extremelly fast, so they do tend to ingite the wet vapors from normal ignition more quickly. There are a few places on line that offer those types of things for cars to help with mileage, but if the car is computerized, it won't work. Computers are set up to only deliver what the manufacturer says the car will deliver. But carburation is not so. I've considered doing a little hose rerouting on my MC to gain benefit, but it may mess with the fuel air ratio too much, and there's the problem of flooding once the thing has sat a while.


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