Improving Mileage

["Tom Brown" <tbrown@xxxxxxxxxxx>]

Scott:

You are the first person I've ever heard complain about 37 mpg.   Try these
things:

TIRE INFLATION:
One thing you can do is keep the tires inflated to 38/42 at ambient.   That
means not in your heated garage, but outside ambient.  The correction factor
is to add 1 psi for each 10 degrees difference between the temp where your
bike is parked (i.e. 60 degrees) and the average outside temp (i.e. 40
degrees).  Would mean that you'd fill to 40/44 in your warm garage.   

More air = better MPG and usually longer lasting tires but also can mean
dicey handling on gravel or slick streets.   Beware of over inflating the
front tire especially.   

Tire Talk:
You will soon notice that these bikes are hard on tires.  I generally go
through a set in about 6000 miles but have gotten 10K out of a couple sets
that have seen mostly touring miles.   Old tires with lots of straight-line
miles get squared off in back.  This makes the bike handle poorly in turns,
but it happens gradually.  Make a point to do some hard turning/swerving on
the bike each time you ride (not with cold tires, though). There is nothing
finer than a new set of tires for an RT.   

Since you're in economy mode here, I'd suggest Bridgestone 021s when you
replace.  (other listers may know of a bargain tire that lasts, but these
last and are fun.) Bridgestones are cheaper than other brands and this 021
is their newest, with hard compound in the middle and softer compound on the
outside edges.   Makes for a longer mileage tire that corners well.   I just
ran a set of these and liked them a lot.  I got 10k on them.   They were
really ready for replacement, but still rideable.  The 021 has an improved
tread on the front for less cupping.  That's important for a commuter bike
because the front brake gets used a lot.   

Southwest Moto Tires is a reliable source and has really good prices.  I'm
in Chicago.  Don't know what freight will be do DC.   Dealers generally
charge a bit more for mounting if you don't buy the tires from them.   Work
something out before you need tires.   

WARM-UP:
The other thing you can do is avoid idling the bike to warm it up.you get
zero mpg while this is going on.  Just ride conservatively until it's fully
warm.that means the temp gage says the oil is warm AND all the metal parts
of the engine are warm too.This takes about 20 minutes of riding.   Never
flog your bike until it's warmed up fully as described above. 

WINDSCREEN:
If you have a giant touring windscreen, consider a smaller one.  I like the
Aeroflow for this bike.  They only make one size and I think it's the right
size for most riding.   

OIL CHOICE:
If you're using 20/50 non-synth oil in the engine, consider using 10/40 for
winter and consider synthetic. 15/50 synth is OK.  Mobil One and other
automotive synthetics will cause more valve noise than BMW synth, but it
doesn't seem to hurt anything.  Silkolene and some other motorcycle oils are
pretty good.  If you can find them cheaper, get them.  

Some people are using Rotella diesel oils for their bike engines.  This is
good if you don't have a CAT on your bike.  They are cheap and lube very
well, but they are not good for the CATs.    

Definitely use BMW synth gear oil in trans and final drive.   Bike shifts
better, takes less time to warm up and this stuff doesn't turn to Jell-O in
the cold.   Don't substitute.use BMW synth gear oil for trans and final
drive.  It's better.  There may be a substitution that works as well, but I
haven't found it and I've really looked.   Remember, it's expensive, but you
only use a little bit and not that often.  Synthetics always help MPG, but
BMW synth in gearbox and final drive are a good idea regardless of MPG.
Shifting and lubrication are just better.  You have a very hot CAT sitting
under the transmission and an "old school" gearbox that needs all the help
it can get.  BMW synth is the best compromise between gear noise and nice
shifting.  

DRIVING CONDITIONS:
Obviously, short hops with lots of braking are not great for mileage.  If
you're using this bike to go to the grocery store in addition to riding it
to work, well, accept that mileage will suffer a bit, especially in colder
weather.  

OIL LEVEL:
R1100 engines are happy when the oil level is not above 3/4 of the circle
indicator.  They can go right to the bottom of the circle and a bit below
without engine damage.  Overfilling is easy to do with these bikes because
the oil coolers tend to trap oil.  The result is that you get a false low
reading, then top up to find that you've overfilled.   Overfilling causes
the crank to splash around in oil and hurts mileage.   It also causes oil to
be sucked into the air box.  You can check this by removing a small plastic
bayonet plug in front of the rear wheel at the bottom of the black plastic
air box.  If oil comes out, someone's been overfilling.   Just drain it out
and replace the plug.  It doesn't hurt anything unless it gets so full it
gets the air filter wet.  That would be unusual.more likely you'll get an
ounce or three.  

The best way to check oil is to only check after the bike is really fully
warmed up.   I like to put it on the side stand when I garage it, then
center stand in the morning for a minute while it's cold.  If the oil reads
low when it shouldn't, I don't top up.  Instead, I check again the next day.
If it doesn't come back up for two or three days, I'll add some, but only to
the halfway point (3/4 if I'm going on a trip or I'm really confident that
it's really down on oil).  If it was at half one day and reads empty the
next after only 50 miles, I know it's a false reading.  

SURGING/LEANNESS
If your bike is not surging at all, it could mean that the cat code plug has
been removed from it.  This will really hurt mileage and may damage the CAT
over time ---but the bike runs great!   

The cat code plug is a yellow (marigold?) plastic cube in the fuse box under
the seat.  Remove the black cover and look around.  You'll see a bed of
contact slots with a square box plugged in to some of the slots.   If you
just see contact slots and no colored cube, you need a cat code plug.cheap
from the dealer or cheaper from a BMW bone yard. 

Note:  There's another colored cube for the 4 way flashers, but it's not on
a contact bed.  It's in its own little cubical.  If you turn on the
flashers, it'll make a little clicking noise.   There may be other hints
that it's a flasher.It's been a while.   

If your bike isn't surging, you really don't want to change it unless you
have no cat code plug.   Believe me, bad surging on a commuting bike is not
good.  

Surging isn't strictly caused by the bike running too lean.  It's caused by
the bike running too rich for the O2 sensor's liking.  When this happens,
the computer defaults to a "lean mode" that surges like hell.  When the 02
sensor sends an "all clear" signal, the computer goes back to the rich
settings and the process starts all over.  The result is a maddening
non-linear response to throttle opening at the RPMs you really need when
riding around town.   Don't go there on purpose.  You probably won't save
any gas and you'll hate what happens.

The difference between surging bikes and non-surging bikes is probably just
the sensitivity of their 02 sensors.   Find a sensor at the low end of the
sensitivity tolerance and your bike will not surge.  Find one with high
sensitivity and it will.   It's really too bad no one has figured out how to
stick a little resistor or something in the 02 sensor circuit to solve this.


Twin Plugging:
Finally, if you really want to get better mileage and no surging, get the
twin-plug treatment from San Jose BMW.   You have to remove the heads and
send them, but they turn them around quick.  You will get better mpg because
all the fuel gets burned from the cylinders every time, surging is gone
because the complete burning means the 02 sensor isn't going to send that
evil signal to the Motronics anymore.   

The cost is somewhere between 450 and 500 bucks plus a bit of your time and
effort.   They provide all the wiring etc. to wire up the extra plugs, they
drill the heads for the new plugs.  In addition to a few extra mpg, you'll
notice better performance and smoother surge free running.  It's supposed to
be a surge fix with side benefits, but one of the benefits is mpg.    

This setup is really nicer than the newer 1150 twin plug setup because BMW
chose to modify the Motronics for lower emissions lean-burn on the 1150
rather than just letting the engine run better.  They run hotter instead and
don't offer much more performance than the 1100s if any.  .but no surge.   

If you are commuting, you're probably riding 20 miles or less at a time.  A
good bit of that is in traffic.  It's cold out.   Your mileage is pretty
typical, I'd say.  These suggestions will improve things, but not to an
amazing degree.   I'd venture a guess that burning a full tank of gas out on
an interstate at 65-70 mph would yield a figure in the low to mid 40s on
your bike.  That ain't bad for one of these.   

If you're looking for a single magic tweak that will easily give you an
extra 5-10 mpg, well, there isn't one.  

If you want to have a bike to save money, you should have a smaller
displacement bike.  V-strom 650? They're really good and have great power
when you kick the revs up.  The rest of the time, they're adequate for most
conservative riding situations.   MPG is huge on regular.    

If you want a big, fairinged BMW that will give you 5-10 mpg more, get a
1200RT.  I can't believe how good these new engines are.  I get 7mpg better
than my 1150 got.   I get more power and it's smoother.   

-TB
'99 R1100RT traded for
'04 R1150RT twin-spark, traded for 
'05 R1200RT

Chipped and piped and air cleanered '00 Aprilia Mille R (for my wild side)

>Date: Sat, 1 Dec 2007 19:55:46 -0800 (PST)
From: scott Baxter <rg500g@xxxxxxxxx>
Subject: Improving mileage on an R1100RT

>I've googled "+R1100RT +MPG" and found a number of sites that reference gas
mileage to one extent or another.  Presently I'm getting 36.5 MPG on the two
tank refills I've made after purchasing the bike. 
About the same MPG each tank.  From what I'm seeing this is on the low end,
but not low enough to put the bike in the shop.

>What can be done to maximize mileage?  If it's a choice between MPG or
surge, right now I"ll take MPG. 
The bike is to my knowledge bone stock, new stock air filter I put in, valve
adj today, fresh engine, trans, and final drive oil, I don't whack open the
throttle to revel in the intake honk, no lugging, no 'sporty'
riding, simple use of the bike as transportation.  Air temps 30F in morning,
driving 40% city, 60% beltway cruising at 70 or so.