What MPG should I expect?

Hey guys, I have an 82 R100 (naked) that gets about 39 mpg on the highway at moderate speeds, 60 to 70 mph. I don't ride it hard when I'm checking the mpg. My 75/7 got consistently 45 mpg. The carbs have just been rebuilt and it runs great, but I think I should be getting better mileage. What should I be getting?

Ray

breaking in a new top-end on a '78 1000cc. and running in the 3000-3500 area I got about 47. Up at 4200 to 5000, about 42.

You are in the mottom end of the ball park. My 81 R100RT gets 45MPG if I drive it hard and closer to 50MPG if I take it easy. Road speed makes little difference till I get over 85mph, but keeping the revs down to 3000rpm or less gets me into the 50MPG range. But then I just have to give it a go to clean out the system, or at least that is the story I am sticking to.

My Brother-in-law's 77 R100 naked bike averages around 45MPG mostly rural riding at 50-70 mph

When I bought my 1980 R100 a few years ago I was getting a disappointing 38 mpg. After fixing and adjusting a lot of things, including the carb rebuilding, I now get a consistent 44 mpg average. I think it was when I bought the carb synch tool (Twin Max?) that I finally got to where I am now. Trouble is that I have to go through the same process now with the R100RS (36 - 38 mpg) and the R60. I am not even going to quantify the R60 right now 'cause my son is learning how to drive on it!!

Ya, I think it's running a bit rich. I rarely have to use the choke to start it. I keep the rpms between 3000 and 4500, unless I'm being chased, and cruise around 4000.

axlray13 said:

The carbs have just been rebuilt...

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What does this include? Did you replace any parts, such as the needle jet and jet needle? After a number of miles, the steel needle rattles around in the brass jet and wallows it out, making it run richer for a given setting. Since you're running around at moderate speeds, you're probably operating in the jet/needle part of the carb, the transition area between idle and full throttle.

Did you replace the floats? Over time, they will not float as well and sink, creating a richer condition. Did you set the floats at the proper level? If they're set to allow more gas into the bowl than required, the fuel level will be high, which also contributes to a rich situation.

When I first got my R100/7 with 22K on the clock I was getting around 45 overall, running it at 4000 or so, now with 170k and only a ring set change out at around 70k I'm getting around 40-42 overall but my compression is down to around 100 so I know it needs a topend job. never run it below 3K as it just doen't like it down lower.
My old 600's, both /5's used to get around 45-47 back when gas didn't have any corn-squeezing in it na I ran those pertty hard and rode mostly back roads, lots of hills and east coast mountains, 2000-3500 ft. elevations. I really don't worry about MPG other than an indication of operating condition.

My LT does better than any airhead I've owned, buts its a whole nother machine!

RM

I get a consistent 44-46 mpg both in and out of traffic. Once I get up to speed, I try to maintain the RPMs.

- I commute on the Wash DC beltway and surrounds (mixed driving)
- 50-75mph speed
- Generally shift at 4500 and settle in at 3700-4100 rpm
- My bike has a butt ugly Windjammer fairing, large touring/system cases
- New Cee Bailey windshield
- Stock Bing 40mm's (new diaphrams, needles, atomizer, o-rings, bowl gaskets and synched with mercury guage)
- K&N air filter
- Dual plugged (but I run high test anyway hoping it'll burn off 8+ years of sitting)
- Kiehan pipes
- Removed emissions gear
- New Metzler Lasertecs 28psi front, 29psi rear

Even though it has the stock electronic ignition, it also has (came with) a Dyna ignition booster, presumably to ease starts on a dual plugged model???
Seems to be debate over the effectiveness of this and I don't *think* it matters for MPG under way, just thought I'd mention it.

When comparing mileage from last year or maybe a couple years ago to the mileage you get today you have to factor in the fact you cannot buy gasoline without ethanol added today. This is an automatic cut in fuel economy.

odometer/tripmeter accuracy

This is a factor to consider when comparing bike-to-bike.
I was all unhappy about an 82 r100rt I had bought, rebuilt carbs, etc etc - yet I was only getting 35-38mpg. The bike runs great. And the speedo unit is correct for the final drive.

I happened to fill up and drive home from a known 22 mile run. but my tripmeter had only recorded 18. After doing the math, I was all upset for nothing.

My naked '81 R100 gets 42-45 mpg on backroad fun riding. I can eke out a bit better if I baby it once I got 50 MPG but that was pre E10 gas. On E10 I got 44 on last weekend's ride.

After I cleaned the carbs and set both needles to the same notch(!), I was getting 45+ with my '83 R100RT.