FUEL ECONOMY: What do you get, How to Improve it?

[BMWzenrider]

Given the recent trend towards sustained higher fuel prices I thought it might be time to take a serious look at the fuel economy of sidecar rigs and what might be able to be done to improve upon it.

I know that on my rather limited fixed income the cost of fuel has begun to become a factor in my travels, and it is just bound to become worse.

For my current rig I have been trying to keep records of fuel consumption as well as recording data from both the on-board computer and my GPS when possible in order to have something to compare over time and a range of variables. The problem is sorting out what is relevant, what isn't, and factoring for uncontrolable variables like wind/weather/traffic/terrain...

Or am I just shooting into the dark and it is hopeless???

In my next post I will show what I have put together so far as a first pass at trying to put the data together in a form that resembles something that can be interpreted in some way...

Feel free to chime in with what kind of fuel economy you have been getting with your rig, what the rig is (tug/chair/speeds/etc) and if you have done anything in an attempt to improve fuel economy and what the results were.

THANKS!!!

[BMWzenrider]

Here is a graph that I put together with the fuel usage data that I have so far:


http://bmwzenrider.smugmug.com/Motor...1_PN7kH-XL.jpg

What it shows in the upper set of curves is the On-Board-Computer readout of the Average Speed traveled while on the previous tank of fuel both as a single point value and as a 5-point moving average curve to help smooth it out.
The scale for this curve is on the right side.

The lower set of curves are the recorded fuel economy figures in Miles-Per-Gallon (U.S.) as calculated by using the vehicle's Trip Meter or GPS respectively in both single-point value and 5-point moving average curves.
That scale is shown on the left side.

Along the bottom scale of the graph you can see what grade of fuel was used to fill up the tank with at that fueling stop.
For the most part I attempted to use a single grade of fuel for a certain period of time to try to get an average performance curve for that grade of fuel with that setup/driving condition of the rig. However there were occasions when a particular grade of fuel was not available when I HAD to fuel up...

The graph is broken up into regions based upon the running-gear configuration of the rig. This includes the size of rear tire installed which affects overall gearing of the bike, as well as the particular size windsheild and any other wind-blocking devices installed for cold-weather riding.

What this graph seems to show, no surprises; is that the largest factors are Speed, Aerodynamics, and possibly Gearing...

[windmill]

My Ural gets around 30mpg depending how I'm riding it.

Some folks are really in to this, http://en.wikipedia.org/wiki/Hypermiling

[BMWzenrider]

Originally Posted by windmill

My Ural gets around 30mpg depending how I'm riding it.

Some folks are really in to this, http://en.wikipedia.org/wiki/Hypermiling

Thanks for the input!

Yes, I am aware of some of the Hyper-mile sites out there. Don't know if I am ready to cover the whole bike in coroplast just yet...

For my bike the manufacturer states to use Premium fuel only due to the high compression ratio, but it does have an octane sensor and anti-knock sensors in the motor, so I can get away with using lower octane fuel in many cases, as can be seen in the graph.
Generally, there doesn't seem to be much benefit nor penalty for one grade over the other from what I can glean from this presentation of the data.
But I do notice a difference in the power/performance of the bike...

[DirtyDR]

I average 30 on the Ural and around 38 on the GS. These are of course assuming legal and sane speeds. My GS is a Sport model so it does have the lower gearing and at 75 I am pushing the economy anything above 5,000 on the tach fuel economy dissapears.

[Lopperoon]

Consumption is the only thing about my Ural that I dislike.

This means that I am particularly pleased when I get good range from mine! The best I have managed, steady throttle, at about 45 mph was 45 Imperial MPG (37 US MPG). BAsed on that, when I am on the open road, I can probably count on 40 mpg...

Unfortunately, many of my miles are in town at the moment and the cold weather hits consumption too so it can be as low as 28 mpg (23 US).

Things I have done that have improved it was fitting individual foam filters, as opposed to the OEM airbox and removing the sidecar screen. As the engine has worn in, consumption has also improved.
I have even investigated fitting an FI kit, but this is a bit of a pipe dream: if I had the money spare I think it would make an interesting project.

[BMWzenrider]

Here is another graph of my data that I put together.
It shows the calculated fuel economy using GPS recorded miles versus the Average Speed recorded by the On-Board-Computer of the bike.
I again used a moving average curve to smooth out the peaks of the raw data to help show the trend line.


http://bmwzenrider.smugmug.com/Motor...50_bnWZi-O.jpg

It again shows that speed is definitely a strong factor in fuel economy, but it does show a fairly flat range in the 40-50mph range and falling off to either side.
So it appears that cruising at around 45mph is right in the "Sweet Spot" for this rig as well...

[miggins11]

My outfit does about 28mpg with a best of 32! To be fair, that is normally with 3 people on board and sometimes towing a trailer or trailer tent.

[VStromTom]

Wait til the all knowing all controlling increase ethanol content morons in DC and each state let 15% become the norm. The crap settles and stratifies in the storage tanks such that you have no idea what you are actually getting. Ethanol is overall a non-winning proposition IMO. I usually get 10-13% less with ethanol gas than I did before, same bikes, same type of driving, same maintenance, etc.

[Mr. Cob]

Howdy All,

My gas mileage with the Ural has never been better then 35 mpg, never worse then 20. The 35 mpg were when I was on the 2008 Ural Tour of the USA while riding east across the great plains with a nice tail wind, the 20 mpg was also on that trip heading west across the great plains into a hell of a head wind riding in 3rd gear for over a 100 miles at around 50 mph so that I could reach my destination at the end of the day as planed.

My average mpg is around 28-29 mpg in normal riding off road if I am getting anymore then 24-25 I am not having enough fun. As I too live on a fixed income the ever increasing cost of fuel hurts. However I am fortunate not to have to commute to and from a job so the gas I burn is mostly in the form of recreational use. Thus far even if expensive its still affordable, time will tell what the cost of gas will do as regards my riding habits.

[Sidecarjohn]

Our BMW K1 plus Primmer Saluki has returned an average of 42 mpg imperial since we acquired it in September 2007. The best figure 54 mpg and a worst of 34 mpg. I keep a constant record, which may be strange for some, but such a habit has identified problems with leaking carbs (yes, two airhead Beemers), and a leaking fuel tank (so that's why there was a strong smell of gas) on the K.

Use a simple spreadsheet program to keep records, plus happy with accuracy of figures as I have an accurately set up cycle speedo on the bike.

Ours is a heavy outfit, and we sometimes tow our teardrop sleeper trailer. When free of towing duties, cruise on the highway around 70 mph, but happy to take it easy when road conditions dictate. Interestingly, fuel consumption hardly affected by towing duties. Dropping off cruising speed to around 50 to 60 mph probably accounts for the similar figures.

When fuel prices started escalating, curiosity started me calculating consumption on a more telling basis, i.e. miles per £. Very sobering in terms of the change in recent months.

[BuellGrrrl]

My experimental subjects have been 3 BMW airheads (R65LS, R80ST, R100GS) and two Motorvation sidecars (Spyder and Formula II). Without sidecars, the R65LS averaged around mid 40s MPG and the R100GS around 40, I never did enough mileage on the R80ST solo to get any definative numbers. The Spyder was first mounted on the R100GS resulting in a 20% drop in MPG to the low 30s. During the R100GS's frequent mechanical maladies the Spyder was hooked to the R65LS and produced about the same mileage. Ultimately I secured the R80ST and mounted the Spyder to it, with mileage dropping to around 30. What's going on here? The R80ST's lower MPG is probably explained by it's rich jetting. That jetting helps it run cool so I'm not changing it. The GS has lousy aerodynamics- one can tell by it's poor coasting performance... But it got the same MPG as the little R65LS. Again, jetting may be at work here- the R100GS is notorious for leaness and while it pulled the Spyder the R65LS had an aftermarket exhaust so I set it up a bit richer.

Now we add another variable to the experiment- the double wide Motorvation F2. I first mounted it to the R100GS, where it dropped MPG by about 2-3 and top speed by a couple MPH. So I suspect the F2 has more wind resistance than the Spyder. Then last year I mounted the F2 to the R65LS and I'm getting 35 MPG? Now to confound things a bit, another variable was added between sidecars- I put a stock pattern exhaust on the R65LS and went back to stock jetting. But none the less, on the R100GS the wider F2 doesn't seem to coast as well as the Spyder, but on the R65LS the F2 seems to coast better. Only guess I have is that the R100GS's barn door fairing, "roo bars", and wider engine are blocking the airflow more between the bike and F2.

I'm thinking of strategies to improve MPG too. My Buell does a bit better than the airheads at around 45-50 MPG solo. My new F800S is absolutely amazing- it's hard to get worse than 50 MPG and I'm averaging around 60 MPG. That suggests even with a sidecar 45-50 MPG is possible. But both these bikes would be difficult mounts that I'd have to haul to a specialist like Claude or Hannigan. That's a thousand mile haul one way, and the only thing I've got that's big enough to trailer both bike and sidecar is a pickup that gets 15 MPG pulling said trailer. So I'll probably "muddle" along with the airheads for some years to come...

[chiba]

I've only run 2 tanks of gas through my rig since getting it back from assembly, but both were consistent - 28 mpg. Almost all the miles have been around town, including a couple of parking lot practice sessions.

--chiba

[Mr. G]

1986 Goldwing GL1200, carburated, with a California Sidecar Friendship II. I seem to get a pretty consistent 33 mpg. It goes down to 30-ish on long highway runs at 70 - 75 mph.

I just bought a Hybrid car as my primary vehicle (25k miles a year) so the savings in gas $$ will keep my motorcycle tanks full for years to come

[BMWzenrider]

Originally Posted by BuellGrrrl

My experimental subjects have been 3 BMW airheads (R65LS, R80ST, R100GS) and two Motorvation sidecars (Spyder and Formula II).

Now we add another variable to the experiment- the double wide Motorvation F2. I first mounted it to the R100GS, where it dropped MPG by about 2-3 and top speed by a couple MPH. So I suspect the F2 has more wind resistance than the Spyder. Then last year I mounted the F2 to the R65LS and I'm getting 35 MPG? Now to confound things a bit, another variable was added between sidecars- I put a stock pattern exhaust on the R65LS and went back to stock jetting. But none the less, on the R100GS the wider F2 doesn't seem to coast as well as the Spyder, but on the R65LS the F2 seems to coast better. Only guess I have is that the R100GS's barn door fairing, "roo bars", and wider engine are blocking the airflow more between the bike and F2.

That brings up a very valid issue; the interaction of having the sidecar mounted closely beside the motorcycle.

Airflow is definitely affected when two bodies come close together. Sometimes for good, mostly to the detriment of both...
I found out quite early on with this current rig that simply having the saddlebag mounted on the side of the bike towards the sidecar reduced fuel economy by as much as 10% just by itself!!!

The problem is that most motorcycles are rather bullet or wedge shaped at the front, pushing air to either side as it moves forward; and so are many sidecar bodies...
What you end up with is a situation where the space between the bike and sidecar is akin to an open funnel with the big end facing forward into the airflow. You are forcing the air into a space which gets narrower towards the rear.
Definitetly NOT ideal!!!

On the EML Sport-2000 model it appears they have tried to control the airflow between the two bodies by having a reverse taper to the nose of the sidecar to maintain an approximately constant distance between the bike and sidecar body.


While Merlin and some others go all the way to the point of having a continuous body panel at the front of the rig to keep airflow out of that space.

Originally Posted by BuellGrrrl

I'm thinking of strategies to improve MPG too. My Buell does a bit better than the airheads at around 45-50 MPG solo. My new F800S is absolutely amazing- it's hard to get worse than 50 MPG and I'm averaging around 60 MPG. That suggests even with a sidecar 45-50 MPG is possible. But both these bikes would be difficult mounts that I'd have to haul to a specialist like Claude or Hannigan. That's a thousand mile haul one way, and the only thing I've got that's big enough to trailer both bike and sidecar is a pickup that gets 15 MPG pulling said trailer. So I'll probably "muddle" along with the airheads for some years to come...

My R1200RT returned between 40-50mpg when I rode it as a solo bike before installing the sidecar. But of course, I mounted a very large sidecar to it, so the relative fuel economy penalty has been pretty high...

When I had my Hannigan installed I pre-ordered the sidecar and they had it built when I rode in for my pre-scheduled installation appointment. They gave me a loaner for the three days that it took them to do the work, and then I rode the completed rig home. So that would be one option if you go with a newly built Hannigan sidecar.
Otherwise, you could also simply ship your bike to the builder and fly in to pick it up. There are several dedicated bike hauling services available for doing that.