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Old 06-18-2011, 09:36 PM   #31
Stagehand
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Quote:
Originally Posted by supershaft View Post
Anyone who doesn't record their fuel purchases doesn't really know their mileage? Give us a break! A lot of us set the trip meter after every fill up and mentally figure the mileage every time. It's simple arithmetic! With small numbers! I don't need to write it down. I know exactly what mileage my bike gets and I have never written down my mileage outside of internet forums.

I kept a mileage record for a little while on a long distance trip.. but forgot once or twice and then it was all over.

Now when i hit reserve, its almost always pretty much exactly eight gallons. The mile I will hit it at varies from 260 to 300, which divided by 8 is easily mid thirties someplace. I guess its been 20K since I took the carbs down completely. I used to get better mileage before I went with Bings recommended upping of the main jet size.
I have had a hankering to put a collector back on the exhaust as well, and ditch the Y pipe. If I'm going to get mediocre mileage, I want the midrange grunt back that I'm supposedly missing out on.
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Old 06-18-2011, 09:44 PM   #32
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40 MPG most of the time, but I can get it up to around 50 if I keep the speed below 60. Yeah right, like I can do that.

It doesn't help that I'm the prototypical Human Air Dam.
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Old 06-18-2011, 11:19 PM   #33
BrokenR80RT OP
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Quote:
Originally Posted by supershaft View Post
I have never needed a journal to keep track of all that stuff. Maybe all the jokes I heard as a kid about beemer riders being pipe smoking journal nerds set my mind to doing without them? People asked me what I thought of the first MOA National I went to. I had a great time but I wished I had a little hand held sign stating that I would not discuss mileage and tire wear journal entries and maybe another one that said Star Trek Convention with a big arrow pointing away from me! That would save me a lot of time at a big rally!

Supershaft!! Yes, I keep a captain's log in my toilet and on my bike.

Really, I'm just trying to help all of us: MPG = Miles travelled/gallons of fuel consumed. Need more info? Let me know.
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Old 06-18-2011, 11:29 PM   #34
alister102
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mid 20's to mid 30's on a 78 r100 with flat slides. I ride the bike pretty hard, and while I'm not happy with the mileage I wouldn't trade the performance for the bings, it's just too great a difference. now I haven't used a round slide carb on this bike, but I do think it has more to do with how the throttle's used and I'm not going to change my riding style.
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Old 06-19-2011, 04:03 AM   #35
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I have 40mm carbs and RS heads on mine and got 44mpg with the RS fairing. It's naked now so that has dropped to the low 40s to mid 30s depending on the level of enthusiasm and roads.
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Old 06-19-2011, 10:06 AM   #36
Quedok
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R80st

My R80ST with 1000cc kit gets only about 36 mpg. If I baby it 40 is possible but the RPM is too high with stock gearing to get better than 40. I had an 83 R100RS that got 53 on a trip from LA to Vegas but I rode is at a constant 70 MPH, all the way on one tank!
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Old 06-19-2011, 10:09 AM   #37
BarryT
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On my R75/7 I just got about 41mpg and that was cruising along at 75-80mph.
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Old 06-19-2011, 10:47 AM   #38
caponerd
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Quote:
Originally Posted by supershaft View Post
Anyone who doesn't record their fuel purchases doesn't really know their mileage? Give us a break! A lot of us set the trip meter after every fill up and mentally figure the mileage every time. It's simple arithmetic! With small numbers! I don't need to write it down. I know exactly what mileage my bike gets and I have never written down my mileage outside of internet forums.

The amount of fuel it takes to fill the tank can vary depending on numerous conditions. Some you may not have any control over.

I've stopped at a number of gas stations regularly during my career as a field service engineer, which always gave me less gas than the number of miles I'd covered since the last fillup. Supposedly, the DOT is expected to monitor gas pumps, but these stations managed to avoid that somehow.

Averaging your fuel consumption over a longer period of time than just one fillup to the next can be useful.

Another advantage to recording fuel purchases is that (assuming you really like to know what your fuel economy is at any given time), you don't have to do any arithmetic in your head or get out a calculator whenever you buy gas.
I have a pen in my coat pocket, and I write my odometer reading on the gas recieipt (takes about 15 seconds) then put it, and the pen back in my pocket. At the end of the day, I'll usually have 2-4 reciepts, information from which can then be copied to my planner (takes about 5 minutes).

Very little time wasted, and I can go back later and get the important numbers if I want.

Anyhow, suffice to say that this is one type of "anality" which I'm not ashamed to admit I'm guilty of.
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Old 06-19-2011, 10:52 AM   #39
caponerd
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Quote:
Originally Posted by alister102 View Post
mid 20's to mid 30's on a 78 r100 with flat slides. I ride the bike pretty hard, and while I'm not happy with the mileage I wouldn't trade the performance for the bings, it's just too great a difference. now I haven't used a round slide carb on this bike, but I do think it has more to do with how the throttle's used and I'm not going to change my riding style.
How much better is the performance? I've never gotten less than 32 mpg, running a full RT fairing. It goes up considerably when I install my RS fairing.
I've been treating the bike a bit more gently the last couple of years, but I used to ride it pretty hard most of the time.
Since I use mine for commuting to work and for errands, I'll trade economy for whatever performance improvement you can gain from running different carburetors.
If I need to go fast, I have an Aprilia for that.
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Old 06-19-2011, 10:54 AM   #40
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Charted Fuel Economy.

I broke this out by ADV, BMMOA and Total. Seems like both sights get similar average numbers with slightly different distributions:



OK.....I'm a geek!
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Old 06-19-2011, 11:05 AM   #41
caponerd
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Quote:
Originally Posted by BrokenR80RT View Post
I broke this out by ADV, BMMOA and Total. Seems like both sights get similar average numbers with slightly different distributions:



OK.....I'm a geek!

Maybe I should send you a copy of my milage records.

My extremes on the RT are 32 at the bottom and 40 at the top. Both extremes are rare. Usually, I see 34 in town and 38 on the highway.
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Old 06-19-2011, 11:40 AM   #42
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Quote:
Originally Posted by caponerd View Post
The amount of fuel it takes to fill the tank can vary depending on numerous conditions. Some you may not have any control over.

I've stopped at a number of gas stations regularly during my career as a field service engineer, which always gave me less gas than the number of miles I'd covered since the last fillup. Supposedly, the DOT is expected to monitor gas pumps, but these stations managed to avoid that somehow.

Averaging your fuel consumption over a longer period of time than just one fillup to the next can be useful.

Another advantage to recording fuel purchases is that (assuming you really like to know what your fuel economy is at any given time), you don't have to do any arithmetic in your head or get out a calculator whenever you buy gas.
I have a pen in my coat pocket, and I write my odometer reading on the gas recieipt (takes about 15 seconds) then put it, and the pen back in my pocket. At the end of the day, I'll usually have 2-4 reciepts, information from which can then be copied to my planner (takes about 5 minutes).

Very little time wasted, and I can go back later and get the important numbers if I want.

Anyhow, suffice to say that this is one type of "anality" which I'm not ashamed to admit I'm guilty of.
I agree that a larger sample than by the tank might be informative but I have no real need for the info. Mileage varies SO much from riding technique and wind and what not that after a certain point it is mostly about innumerable varying conditions. That's bad science. I personally pick some other fires to piss on. Besides, I think doing simple division in your head is good exercise!
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Old 06-19-2011, 11:45 AM   #43
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Quote:
Originally Posted by BrokenR80RT View Post
I broke this out by ADV, BMMOA and Total. Seems like both sights get similar average numbers with slightly different distributions:



OK.....I'm a geek!
Have fun with it. I only hope you got out your lab coat and pipe out while making the graphs. Penny loafers with no socks? And a sharp haircut! Oh the horror!
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Old 06-19-2011, 12:09 PM   #44
Lornce
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I like to think of it as a more holistic way to approach building a performance engine. Any idiot can build a crude gas pump and spin it up to high revs with no regards for efficiency. KTM's been doing that for years.

Start with building a motor to higher standards of efficiency that makes good torque and then find a way to spin that to higher revs for improved power.

It's the approach Rotax appears to have taken with their 800 twins. Compare them to 950 KTM's which make slightly higher peak power while using more than twice as much fuel.

That's just dumb.

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Old 06-19-2011, 12:26 PM   #45
fishkens
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Quote:
Originally Posted by BrokenR80RT View Post
I broke this out by ADV, BMMOA and Total. Seems like both sights get similar average numbers with slightly different distributions:



OK.....I'm a geek!
Nice. Can you show the y axis as % of total? This would show the differences between ADV and MOA more clearly.
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