Gas mileage

[Air4Life]

http://www.fuelly.com/motorcycle/bmw/r65

Check out that "Bunny"... with the 43 mpg's

[Barry]

Good to see people are monitoring MPG.  I've recorded every drop of fuel that's gone into the tank for over 5 years now.  The graph shows a clear summer/winter cycle and the improvements year on year corellate with adjustments in the service record. Subtract 20% for US MPG.

Year 1        - Low mpg was due to a gunked up emulsion tube.

Year 2 & 3  - after carbs overhauled

Years 4 & 5 - after leaner idle mixture screw settings

Year 6         - No single thing I can credit for exceptional results this    
                    last summer. Probably due to a combination of lower
                    cruising speeds due to absence of a regular motorway    
                    run and further leaning out of idle mixture enabled by  
                    slightly softer cam timing. Could also be a contribution
                    from addition of an upper cylinder lubricant in the form
                    of 1:640 2 stroke oil though that's very far from an
                    assertion on my part.

[Air4Life]

Very nice Barry.  Those numbers are quite impressive (factored differences in too)! What does that graph represent in average travel speed?


Bunny did another fill up that was 98% highway at nearly all steady 65 mph = 4800 rpm's Which yielded me 47.1 MPG.  That's with my full shield plowing through.

[montmil]

I can't control my right wrist on any of my motorcycles.

Gas mileage? Quien sabe? I don't care. That's what the petcock's reserve position is for. Right?

[Barry]

What does that graph represent in average travel speed?
 

I think you can guess from the figures I don't ride very fast. In the summer I used to do a regular motorway journey at 65-70 mph that returned 65 mpg. I very rarely do that now and speeds on narrow country lanes are more like 45 - 55 mph where it's easy to return 75+ mpg.

Low figures in the winter reflect journeys being almost entirely very short 8 mile round trips to work. I Briefly hit 50 -  55 mph but mostly 35 - 40 mph. I would do better in the winter if the journeys were long enough to warm the engine up properly.

A lot of the miles are with my wife as a passenger which surprisingly has little effect on economy. That's probably because she doesn't weigh much and I ride more slowly than when solo.

For me the key to tuning the carbs for good economy is the realisation that typical cruising speeds use only 1/8 to 1/4 throttle which means the mixture screws still have a big influence. You can set the mixture screws quite weak for good economy without having an adverse impact on acceleration which tends to use more than 1/4 throttle.

[Air4Life]

I know what you mean Monte.  It was not easy staying 65 mph the entire way; at least I was moving along with most of the truckers.  Usually I'm doing 70 to 75 mph.  Next time I will see what difference the added 1000 rpm's means fuel wise.

The only time I wish I had dual disks is on my return trip over the garden state parkway.  I'm usually tired from the 6 hours of almost all saddle time as I reach the last 45 minutes of the trip.  There are thousands of cars zipping up to 70+, then they all tap their brakes at the end of the 1/2 mile jaunt right back down to a crawl - this gets repeated, again and again.  Most don't appreciate my spacing technique...  That's the only time I really could use the adding stopping power.

I'm sure its the same in your neck of the woods.  I bet Dallas is pretty wild...  

[Air4Life]

Barry,

Normally I'm of the mindset, that if it aint broke...  but your numbers are ridiculously fine and I just might have too tinker.



 

[montmil]

...I'm sure its the same in your neck of the woods.  I bet Dallas is pretty wild...  

Absolutely.

Although I live nearly forty miles north of central Dallas, I've been making frequent trips into the monster's lair; seeing an ophthalmologist. I have been experiencing the exact traffic you've so perfectly described.  

Trying to maintain a safe following distance is an exercise in futility -be it in a car or, even worse, while on a motorcycle. I don't believe any large city is exempt from this challenge.

Fortunately, I can be outta my village in three minutes flat; traveling the cowboy way and not seeing another vehicle for at least an hour. Motorcycle mental health is just a twist grip away..

[Dave 2]

Nice, D2

[Ed Miller]

Mine gets around 45 mpg.  I'm more surprised at all the others.  

[tvrla]

 Mine isn't a 650 any more, and wasn't when I got it, so it doesn't really fit in this discussion. It's had the San Jose hop up treatment to 850cc with venolia pistons, head work, and flat slide mikunis. I've also upped the final drive to 3:36 from the stock 3:56.

When I got it (badly needing tuning) I think it was getting in the low to mid 40s for mileage. But since the new rings, re-jetting carbs and taller drive, I've gotten as high as 50mpg, though 48 or so is pretty common.

Though I tend to take it easy on acceleration and deceleration (once I'm going I don't slow down) the LS is so much fun to ride, I can't help but ride it more spiritedly. And still it gives me great mileage!

[Bob_Roller]

Since the fuel supply has 10 % ethanol and the speed limit on rural highways was raised to 75 mph, my fuel consumption went from a consistent 45 mpg, to 39-40 mpg with my '81 R65 .

Before ethanol in the fuel and a speed limit of 55 mph, 50 mpg was common .

My oilhead (1150) gets 58-60 mpg on rural highways at 80 mph .

[Barry]

Bob's oilhead shows what's possible when the fuel is metered and burn't  efficiently.

[Ed Miller]

Mine isn't a 650 any more, and wasn't when I got it, so it doesn't really fit in this discussion. It's had the San Jose hop up treatment to 850cc with venolia pistons, head work, and flat slide mikunis. I've also upped the final drive to 3:36 from the stock 3:56.

When did you get that one?  I don't remember seeing it.  I haven't been going to much of the Airheads stuff lately.  There's always stuff to do.

[tvrla]

Yeah - I haven't seen you around lately, Ed! I thought for sure see you at Tom's tech day after Thanksgiving.

I've had the bike about two and a half years now. First year or so worked on it a lot, off and on. It was pretty rough, scrapes, bent scraped levers, missing battery covers, bent wheels, broken fins, ripped seat, loud two into one, wasted tires, on and on. But the price was right, it shifted well, felt strong, but made some weird noises that turned out to be carbon build up on the piston that was contacting the valves. The wheels and fork sliders were machine shop gray and the rest of the bike is white. Good quality paint, but needed a bunch of touch up. Eventually painted the wheels and sliders silver, so now it looks pretty sharp! I wouldn't have picked white, but it's grown on me.

Rob - I'd gotten in the area of 52mpg with the R1100S and thought that was pretty good. But you beat me, hands down!