Gas mileage expectations?

[Beemertom]

Guys, what gas mileage should I expect from my 1994 r100rt? Stock except that I have removed the epa plumbing... I only get about 150 miles per tank before reserve. Does that seem 'normal'?

[20774]

What's the overall gas mileage? 30mpg? 40mpg? Seems a little low, but I'm not sure how many gallons until reserve for your tank. It could be that the vertical straw for the main tank is quite high, giving a short distance to reserve. Has it always been like this? Are you first owner? What's the general state of tune...how does the bike run? Do the plugs look sooty as evidence of running rich? If the carbs have never been overhauled, it might be time for it. Floats can sink in the gas, causing a rich condition...they should be replaced somewhat routinely. The jet needle can be worn resulting in a rich condition at 1/3 to 2/3 throttle operations. Maybe other late model RT owners can provide more things to check...

Kurt in S.A.

[lkchris]

Seems normal unless highway driving.

Later models have smaller fuel capacity than earlier bikes.

[Bob_M]

My 1982 RS gets 42 MPG. It is running synthetic oil, but the mileage was the same with dinosaur oil.

[jmerlino]

My '82 gets 40-45 depending on the where I hold the revs. If I'm on a long slab ride, and I'm holding it right around 4K, it'll give me 45 or so. If I'm on back roads and running in lower gears up around 5K, 40 is more like it. Pretty good regardless.

[PHMarvin]

Hi,
My '81 R100RT and '84 R100RS both got in the mid 40's usually, either with regular (leaded) or premium. Once, on a long trip, loaded, the RS only got 38 for a tankfull, but later got more. Harriet's '95 R100RT was hard pressed to get 40. Regularly it would get 37 or 38. If I had ever had to rebuild it, I would have gone to '81-'84 R100 heads and 40mm Bings. The '95 was smooth, but I'd prefer the '81-'84 motor, with the appropriate repairs to the valve seats, new guides and valves.

[The_Veg]

I have a '95 R100R that in it's best state of tune gets maybe mid-30's. Best state of tune does not last very long either. It requires a constant battle to keep the mileage up.

[Friedle]

I expect to have enough gas to make it to the next gas station.

My expectations aren't always met. :dunno

Friedle

PS: In my experience, adding bigger gas tanks just means I run out of gas farther away from the nearest gas station. It's tough to explain to the wife why you spent so much money on those Heinrich tanks and STILL run out of gas!

[R100RS]

35-38 mpg is normal for my 88 R100RS on the highway.

[88bmwJeff]

My 88 R100 RT gets between 33 on the low end to about 38 on the high end. I am kind of heavy throttled. Riding style does play big into this. On a rare occasion or two, I've noted 40. When I rebuilt my carbs, I included the Bing "rejet" kit. I don't know how this affected my mileage, since I rebuilt the carbs in the first few month of ownership before I tracked the mileage. Plus the carbs were in desperate need of a rebuild.

Veg. You indicate "Best state of tune does not last very long either. It requires a constant battle to keep the mileage up." FWIW, I feel the same way.

[The_Veg]

Thanks Jeff, I do feel a little better. Dunno what size carbs your 88 has but I have 32s, which a Bing rep told me were seriously underjetted for US emissions compliance. I installed the larger ones the rep recommended and saw a slight decrease in MPG, but a slight increase in performance. Sounds about right. I have not done a rebuild, but I have replaced the floats. I can be heavy on the throttle around town, but I'm pretty steady on the highway. 30-33 Is usual.

[widebmw]

I have got 45mpg two-up on a nice slow ride. 2 days later I got 25mpg at high speed into a head wind. Most of the time I get 35 - 38mpg on a 92 R100R. With a RT pushing that bigger fairing it may be less.

[mikea]

:burnout Thought I would reply to this thread since it makes me feel better about the mileage I'm getting.

42-45 mpg on a '92 R100R in a variety of conditions-interstate to ripping through the mountains.

Mike

[lkchris]

If you want fuel mileage, get a Volkswagen TDI.

Motorcycles are hobbies and who cares what they cost?

[The_Veg]

Kent, it's not the cost it's the range.

[rocketman]

I get around 38 on my 78 R100 with topend rebuilt at 20K ago. Pretty much stays the same be it twisty road or Highway, loaded or just day tripping.
My tank goes to reserve at 5.5 gal. and has a gal. reserve.

RM

[88bmwJeff]

Dunno what size carbs your 88 has but I have 32s, which a Bing rep told me were seriously underjetted for US emissions compliance.

Veg. I have the 32s as well. When I rebuilt them, I went to town with new needle jets, jet needles, float needles, floats, all gaskets, diaphragm, new return springs as well as the rejet kit.

BTW how much did the fuel economy drop?

[The_Veg]

I'd say it dropped just enough to notice, and I usually just figure my MPG with quick-n-dirty mental math while at the pump. Not very precise nor am I keeping much record of trends, but I feel I at least know the ballpark and I almost always have a rough mental idea of how efficiently I'm running.

[bmdubyou]

I seem to be good for around 180 miles before reserve on my '84 R80RT which translates to 40-42MPG fairly consistantly. I'd like to see closer to 50 though.

[lkchris]

I seem to be good for around 180 miles before reserve on my '84 R80RT which translates to 40-42MPG fairly consistantly. I'd like to see closer to 50 though.

Get an R100RT, then.

[BeemoKat]

My bike originally came with the 32mm Bing Flat-Top carbs, which got 43mpg consistently, but also caused frequent valve adjustments from running so lean. I swapped my carbs for some 32mm Dome-Tops, now I get around 33-37 mpg, but with much improved performance and MUCH less frequent valve adjustments. Good trade as far as I'm concerned.

[motolatte]

was having same concerns, new convert to air-heads and was only getting 35-40mpg on '82 rs...

[rinty]

Tom:
Airhead mileage will vary significantly, depending on headwinds, crosswinds, r.p.m., and load. In 1988, BMW reduced the tankage on the "re-born" boxers, by about one U.S. gallon, to about 5.5 with a reserve of about 1.3, to enable the placement of a bunch of new stuff under the tank.
Based on your post, I have calculated your mileage at 33 m.p.g., which is in the lower end of the range.
I like to track the mileage on each tank I run through my '82 RS and it varies from, 35 to 43, just depending on how hard I am playing. I would expect that RT's, with their slightly higher drag, should burn slightly more fuel than RS's
The worst mileage I have ever seen was 29 m.p.g., while punching into a 60 km per hour headwind at 130 km/hr (in the "mid-continent fuel gap", between Harlowton, Montana, and Neihart).
I think you're probably OK, but I would have a good airhead tech check your mixture ratio with the exhaust sniffer.