'94 R100R fuel milage

[velomoto]

Can anyone give me an estimate of how many miles per gallon one should be getting for secondary highway riding? Typical speeds are 45 to 65, not stopping much, no pillion (driver weighs about 150 lbs), and stock fairing/windshield/bags. For compaison purposes, a R12RT on the same ride is getting about 50mpg while the r100r is around 37mpg.

 

Any guesses, hints, suggestions on how to get better milage?

 

Thanks in advance,

Greg

[Paul Mihalka]

Your 37mpg is fair average. The old style carburettor bikes are MUCH less efficient than the current fuel injection/electronic control motors.

[ShovelStrokeEd]

You mentioned you live in Colorado, are you down in the flats or up in the mountains? Your bike might not be jetted correctly for the altitude you are running at. As altitude climbs, the air gets thinner and the bike runs richer. The EFI equipped bikes like your buddies R12 compensate for the mixture change automatically. A bike with carbs won't do this and needs its jetting adjusted. A competent BMW mechanic in your area should have a pretty good handle on what jetting is required. At those speeds, you should be getting at least 40, assuming the bike is in good tune otherwise.

[John Ferris]

If you do lean out your carbs for a higher alititude remember if you go lower you will have to richen them back up.

[ShovelStrokeEd]

So long as he jets for about 4K or so feet and doesn't go running full bore across Death Valley, he should be OK. It might even be as simple as dropping the needle one notch just to handle the part throttle cruise. That takes no more than 15 minutes on an airhead. Likewise, a step or so down on the main jet isn't going to burn a piston if he doesn't try keeping up with that hexhead.

[fatbob]

For compaison purposes, a R12RT on the same ride is getting about 50mpg while the r100r is around 37mpg.

 

Any guesses, hints, suggestions on how to get better milage?

 

Thanks in advance,

Greg

 

That is pretty poor for a gently ridden airhead. I get better than that with my sidecar rig! My R90 will do 45+ if I could ride her that gently! I think the jetting of your bike must be for low altitude. I run 245 jets in my 40mm bings, I am also at high altitude. I would suggest consulting with a manual.

 

Bob

[velomoto]

First to answer a couple questions and provide some additional info...

 

The 37mpg is actually about the best the bike gets. Ride hard and the mpg's will drop down around 30 to 32.

 

The bike typically doesn't spend much time at higher elevations. Here in Fort Collins the elevation is just under 5K and most riding is very near that elevation with brief rides up to 8K, and an occasional ride over a pass (10k to 12k) but will quickly return to 7k or below.

 

I'm looking to dial in performance at this altitude, a trip to Death Valley on this bike just isn't in the cards.

 

Are there any good on-line manuals or resources for the airheads or is there a preferred manual I should buy?

 

Thanks again for all the feedback!

Greg

[BABABeemer]

I would re-build the carbs. It should get better milage than that!