Effect of Running in 4th Gear...Fuel Economy - BMW Luxury Touring Community
 
LinkBack Thread Tools Display Modes
post #1 of 35 Old Feb 24th, 2007, 10:21 am Thread Starter
Senior Member
 
BlackBMW's Avatar
 
Join Date: Dec 2005
Location: Delray Beach, Florida, USA
Posts: 188
Effect of Running in 4th Gear...Fuel Economy

I took my LT on a 300 mile run on Sunday (weather was finally decent). I was very concerned with my gas mileage. The OBC showed 34.2 mpg. After fill-up, I got only 150 miles until my fuel light came on (usually means around 25 miles to empty, right?).

Anyhow, I found myself running in 4th gear quite a bit (instead of 5th) at speeds around 60-75 mph. In the colder weather, I run with the stock windshield about half-way up.

The LT is stiil pretty new to me and I have been used to a 6 speed trannie. I ran around 4000 rpm at the 60-75 mph range and I'm thinking that it cost me the gas mileage that most report is more normally in the 40's.

What do you think?

Mike M

2007 K1200GT Dark Graphite
BlackBMW is offline  
Sponsored Links
Advertisement
 
post #2 of 35 Old Feb 24th, 2007, 11:02 am
esa
 
Join Date: Jul 2002
Posts: 78
On my '05 LT, and also on my '99 LT that I used to have (55k), I found that cruising at 4 - 5K in 4th gear would often give me as good or even better mpg than running in 5th. Besides riding style, which has the greatest effect, the things I find that will also effect mpg the most are:

1. position of windshield (the lower the better the mpg)
2. position of the lower wind deflectors (flatter the better)
3. outside temperature (cold weather = less mpg)

Of these 3, the position of windshield seems to effect my mpg's the most.

The LT motor has a sweet spot in the 4k-5k range where it runs very efficiently and therefore gives the best mpg's.
esa is offline  
post #3 of 35 Old Feb 24th, 2007, 11:24 am
Senior Member
 
usmctpdog's Avatar
 
Join Date: Jun 2002
Location: Seattle WA, USA
Posts: 865
You are correct Mike as mine often runs the same...

When I am in the twisties in 3rd - 4th gear and in the R's I often get less MPG than when on the Fwy in 5th @ 55-70 mpg... There I often average 46-53 mpg.

When returning with the bike last March from coastal Oregon to Spokane WA in cold weather traveling **Way Above the posted speed limit I was showing on the BC " 34 " miles per gallon !!!!

Average for me is 46 - 48 on either regular or premium....

I ride for the most fun, not the gas mileage but thankful it is better than my old Hardley - Dangerous 2 cylinder...

47+ Yrs Daily Motorcycle Street riding for Therapy

2012 Victory Cross Country Tour

2007 Black Suzuki DL1000 V-Strom - Sold
2007 Red Moto Guzzi Norge 1200 - Sold
2005 LT Dark Graphite - (Sold)
2005 PearlBlue FJR1300 (Sold)
3 BMW's, 8 HD baggers, 3 Goldwings & 860K + miles later
*Ridin steady since 1973

usmctpdog is offline  
 
post #4 of 35 Old Feb 24th, 2007, 2:06 pm
Senior Member
 
petevandyke's Avatar
 
Join Date: Jun 2006
Location: Dallas, TX, USA
Posts: 1,741
04 and older...

My '04 has that infamous buzz/rattle/grrrrrrrrr right about 4,000-4,200 rpm, so I'm not sure I'd WANT to ride in that RPM range...

Waiting for David Shealey to pipe in (miss ya, buddy, where have you been?) on this, but doesn't logic suggest that if you're in a higher gearing and ratio that allows you to ignite the gas and air mixture in your cylinders 2,500 times a minute at a velocity of say 60 mph, that you'll get better mileage than a lower one that requires 4,000 times per minute? (the reason c-5 and c-6 'vettes with their very tall 6th gear can pull 26 to sometimes 30 MPG at highway cruising speed, even with ridiculously powerful 400 HP v-8 engines)?

I'm currently playing around with the switch I put in between the "brown wire" since Tejas weather is currently below 80 degrees to see if "wire interruptus and higher grade gasoline" equals better mpg than "wire connected and mid grade gasoline"

P

========================================
When life throws you a curve, LEAN INTO IT!!!
2000 R1100RT-P...R.I.P. "Old motorcycle"
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

2004 K1200LT "Lick and Tickle"
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


FU*K Cancer. If I have one more MRI, I'll stick to the refrigerator door.
petevandyke is offline  
post #5 of 35 Old Feb 24th, 2007, 4:16 pm Thread Starter
Senior Member
 
BlackBMW's Avatar
 
Join Date: Dec 2005
Location: Delray Beach, Florida, USA
Posts: 188
Quote:
Originally Posted by usmctpdog
You are correct Mike as mine often runs the same...

When I am in the twisties in 3rd - 4th gear and in the R's I often get less MPG than when on the Fwy in 5th @ 55-70 mpg... There I often average 46-53 mpg.

When returning with the bike last March from coastal Oregon to Spokane WA in cold weather traveling **Way Above the posted speed limit I was showing on the BC " 34 " miles per gallon !!!!

Average for me is 46 - 48 on either regular or premium....

I ride for the most fun, not the gas mileage but thankful it is better than my old Hardley - Dangerous 2 cylinder...
Hmmmmm,

Strange, when my low fuel light went on at 150 miles, I fuelled up (5.25 gallons) which indicated to me that I had about another 30-40 miles left in cruising range.

My reason for questioning the mpg is not because of anal-retentiveness with gas mileage, just that I'd hoped to have at least a 200 mile range per tankful on a big tourer. Hell, I was thinking I would get a 250 cruising range.

One other issue is that since changing to the full Remus exhaust (without re-mapping the fuel injection or installing the "chip") the bike seems to be running rather rich. Lots of sooty residue on the exhaust pipe tip . I know some sootiness is typical, but this seems more excessive than normal.
Near the end of my 300 mile ride I was experiencing some "sputtering" at lower RPMs indicating some fouling of the plugs.

Guess I will just have to see.... as they say.

Mike M

2007 K1200GT Dark Graphite
BlackBMW is offline  
post #6 of 35 Old Feb 24th, 2007, 5:01 pm
Member
 
cfmpilot's Avatar
 
Join Date: Jan 2007
Location: avondale, az, usa
Posts: 96
I took my LT on a 92 mile lunch run today and am happy to report that I did not fall over. Anyway, I played with the windshield position at an indicated 90 mph. It was like throwing a drag chute out as it moved higher. That has to have a major effect on mpg.
cfmpilot is offline  
post #7 of 35 Old Feb 24th, 2007, 5:13 pm
Senior Member
 
Join Date: Oct 2003
Location: , Illinois,
Posts: 188
Wow! I am amazed. I know it is anecdotal but my 99 gets consistantly 50 mpg. After decades of logging flight time I do the same with my motorcycles (neat to read during the snow and ice months) and can support these claims with thousands of miles. I love the FD gear ratio of the 99! I commonly fuel-up reading over 200 miles on the trip meter. The fuel low light comes on at about 225 miles. I use the BC for ambient air temperature.

Carl

K1200LT w/ KLT s/c
K1100LT w/ ECC
KLR-650

N9BMN
FD <> 4%
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


bmwmoa 100984

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Tourdog is offline  
post #8 of 35 Old Feb 24th, 2007, 5:25 pm
Senior Member
 
BecketMa's Avatar
 
Join Date: Jul 2002
Location: Tucson, AZ, USA
Posts: 3,522
<What do you think?>

Makes sense to me.

If you are using the center stand for gasing-up, you are not getting the tank full.

The BC will computer how many more miles left (I never trust it to go with in a few miles of getting gas).

Bob
BecketMa is offline  
post #9 of 35 Old Feb 24th, 2007, 5:38 pm
Senior Member
 
dshealey's Avatar
 
Join Date: Apr 2002
Location: Dandridge (Near Knoxville), TN, USA
Posts: 12,165
Quote:
Originally Posted by petevandyke
----------------------------------
Waiting for David Shealey to pipe in (miss ya, buddy, where have you been?) on this, but doesn't logic suggest that if you're in a higher gearing and ratio that allows you to ignite the gas and air mixture in your cylinders 2,500 times a minute at a velocity of say 60 mph, that you'll get better mileage than a lower one that requires 4,000 times per minute? (the reason c-5 and c-6 'vettes with their very tall 6th gear can pull 26 to sometimes 30 MPG at highway cruising speed, even with ridiculously powerful 400 HP v-8 engines)?-------------------------------------
Been right here, most every day.

Actually, fuel usage is not all that related to RPM, but instead POWER usage. In any given set of circumstances the bike needs a given amount of power at any one time. It is all thermodynamics, BTU in the fuel converted to Power output. If in a lower gear where the cylinders are firing more often you have the throttle more closed than if in a higher gear, thus burning less fuel each crank rotation. Basically, for any given power output you use nearly the same amount of fuel no matter which gear you are in. However, the engine's efficiency changes over the RPM range, so one would have to develop efficiency curves based on the torque/HP curves along with a fuel usage curve imposed on them. Then at any given instant you could see which would be the best gear to be in. As long as kept within the flatter part of the HP curves though, the gear selected has only minor affect on fuel usage.

I don't want to achieve immortality through my work...I want to achieve it through not dying.

David Shealey
Dandridge, TN
EX: '01 Black LT, BAT BYKE (Totaled at 110,000 miles)
IBA SS, BB, BBG, 10/10ths.
No bike now, but maybe in the future.
dshealey is offline  
post #10 of 35 Old Feb 24th, 2007, 8:49 pm
Senior Member
 
retiredjj's Avatar
 
Join Date: Oct 2005
Location: Hoodsport, WA, USA
Posts: 153
Now if you really want to have fun and give birth to a whole new line of forum chat, install a manifold pressure gauge and start comparing mpg with that. M.P. is a more accurate indicator of power being used thus mpg.

2002 R1150GS Adventure (current)
2000 K1200RS
1999 K1200LT (current)
1998 R1100RT
1985 Suzuki GS1150E
1985 Kawasaki Ninja 900
1983 Honda V65
1979 Yamaha XS1100
1977 Honda CB750
1963 Harley Duo Glide
1965 Honda 305
1962 Honda Cub 50
1960 Cushman scooter

Was I being naughty...officer?
retiredjj is offline  
post #11 of 35 Old Feb 24th, 2007, 9:35 pm
Guest
 
11862's Avatar
 
Join Date: Apr 2006
Location: minnetonka , mn, usa
Posts: 637
Go read about pumping loss of gasoline engines. Unlike a diesel engine, the trouble with a spark ignition engine is that the throttle is so simple - yet so inefficient.

Relying on a manifold pressure gage will have us all driving around in 4th gear, wondering where the fuel economy went.
11862 is offline  
post #12 of 35 Old Feb 24th, 2007, 10:07 pm
 
Join Date: Aug 2004
Posts: 713
Simple, really....

In town and around the burbs its just a 4 speed....

When you clear the last light and can stay at 60 mph or higher shift to 5th.... Otherwise its a 4 speed..............Pete
petepeterson is offline  
post #13 of 35 Old Feb 25th, 2007, 3:23 am
Senior Member
 
billybiker's Avatar
 
Join Date: Apr 2005
Location: Grantham, East Midlands, GB
Posts: 112
Once above 30mph its 5th gear for me and leave it alone. Rarely get less than 50 mpg and mid 50s is more normal. Why would you ride along in 4th gear??? Mines a 03 model-does the later model use more fuel? I've just come back from a 3 week course in London doing a weekly commute and it was 152 miles door to door. I managed the return trip with about 20 miles still showing on the BC.
billybiker is offline  
post #14 of 35 Old Feb 25th, 2007, 5:22 am
THE Democracy Doctor
 
jayjacobson's Avatar
 
Join Date: Feb 2006
Location: We LOVE illegals and Socialists, Sunny, Southern Kommyfornia,
Posts: 5,694
Quote:
Originally Posted by BlackBMW
....One other issue is that since changing to the full Remus exhaust (without re-mapping the fuel injection or installing the "chip") the bike seems to be running rather rich. Lots of sooty residue on the exhaust pipe tip....
Mike, having "examined" my tailpipe for soot numerous times on both my LT and GT, I would say the bikes tend to run lean. Now, I can't say that with absolute certainty because I have never hooked an exhaust analyzer to my bikes. I think your soot, combined with low mileage is a good indicator, however. I would start by checking that fuel mixture.

"Those who would give up essential liberty to purchase a little temporary safety, deserve neither liberty nor safety." (Some really OLD friggin' White dude who couldn't have possibly known what he was talking about!) WARNING: Official HATE speech!
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
jayjacobson is offline  
post #15 of 35 Old Feb 25th, 2007, 5:54 am
Senior Member
 
pozo_izquierdo's Avatar
 
Join Date: Apr 2004
Location: Hyvinkää, , Finland
Posts: 1,583
Hey guys, when speaking about rpms and sweet spots etc. keep in mind the BMW changed the overall gearing ratio to higher from ´05 models. (Meaning that engine revs about 400-500 rpm higher at 120 km/h, for instance)

Now I don't remember the exact gearing figures but somebody on the forum surely does.

When I was riding a pre-05 model I noticed a clear difference on how the bike behaved and run on the 5th gear. It was more like an overdrive (and more pleasant on the higways) than the current one. This must have some affect on the mileage as well.

Regards

Ari "the Farkle-Freak-Finn" Ignatius

Hyvinkää, Finland
2004 ('05) LT, Dark Graphite, "Sunset Cruiser II"

Bike trip from Finland to USA:

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


Pictures of various farkle projects:

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
pozo_izquierdo is offline  
post #16 of 35 Old Feb 25th, 2007, 8:55 am
Senior Member
 
billybiker's Avatar
 
Join Date: Apr 2005
Location: Grantham, East Midlands, GB
Posts: 112
My '03 model is 20mph per 1000 RPM.
billybiker is offline  
post #17 of 35 Old Feb 25th, 2007, 2:26 pm
Guest
 
11862's Avatar
 
Join Date: Apr 2006
Location: minnetonka , mn, usa
Posts: 637
So is my '05LT - 3000 rpm @ 60mph.
11862 is offline  
post #18 of 35 Old Feb 26th, 2007, 7:57 am
 
Join Date: Jul 2004
Posts: 208
Gas mileage

your gas mileage will vary based on the following factors:
1. Year of your LT- ( i.e. gearing)
2. Octane of gas used
3. Altitude
4. Weight of your foot at any given moment
5. wind direction and speed
6. gear in use
7. speed driven
8. setting on the Motronic
9. geography of where you are riding
10. condition of engine and tuneup
11. air filter
12. condition of tires and air pressures

As you can see there are so many variables that everyone's average will vary but generally speaking you should get somewhere between 38-50 mpg. Remember that the "computer average" is usually not as good as calculating it manuallly by miles driven divided by gallons used. Ron Ray
ronlray is offline  
post #19 of 35 Old Feb 26th, 2007, 10:59 am
Senior Member
 
Bob204bc's Avatar
 
Join Date: Mar 2004
Location: Newport News, VA, USA
Posts: 189
My experience has shown that the cold has the greatest effect on fuel mileage. Thin, hot air returns the best range. I typically get 48 mpg in the summer and 38-42 in the winter. This does not vary significantly with load or speed (mostly east coast speeds not the western open space speed).

I don't baby the throttle and I never run in any gear at less than 3,000. I read here that someone shifts to fifth at 35-40 mph. Wht would you do that? The bike would respond like a pig.

Bob Chapman
Virginia
2000 K12LT
1978 CB750A (Automatic Cafe Racer Ratbike)
Bob204bc is offline  
post #20 of 35 Old Feb 26th, 2007, 11:15 am
 
Join Date: Apr 2004
Posts: 207
Thin air

Were do you go in VA to get thin air? Mt Elliot Knob? :-)
My gps reads 3100-5000+ on local roads....
I sure the choke has a lot to do with my lower (38-45) mpg for winter driving.
little jake
little_jake is offline  
post #21 of 35 Old Feb 26th, 2007, 11:41 am
Senior Member
 
pozo_izquierdo's Avatar
 
Join Date: Apr 2004
Location: Hyvinkää, , Finland
Posts: 1,583
Quote:
Originally Posted by ronlray
your gas mileage will vary based on the following factors:
1. Year of your LT- ( i.e. gearing)
2. Octane of gas used
3. Altitude
4. Weight of your foot at any given moment
5. wind direction and speed
6. gear in use
7. speed driven
8. setting on the Motronic
9. geography of where you are riding
10. condition of engine and tuneup
11. air filter
12. condition of tires and air pressures

As you can see there are so many variables that everyone's average will vary but generally speaking you should get somewhere between 38-50 mpg. Remember that the "computer average" is usually not as good as calculating it manuallly by miles driven divided by gallons used. Ron Ray

Very good list, Ron.
From the experience I had with my riding buddy Jouko on our last summer CCR trip I would like to add :

13. The amount of "farkles" on your bike.

We both had same year bikes, about the same overall kilometers and we rode the same route (over 11.000 km) with same speed. He got regularly over 10% better mileage than me. The only (visible) difference was that I had four extra Hella halogen lights + RS mirrors to distract the aerodynamics of my bike and Jouko had stock bike in that respect. We both even had the same CB #2 w/wings windshields. (OK, Jouko's was 1" shorter than mine..) Both bikes had been serviced (40.000 km) before the trip.

Anyway, our mileage difference grew even greater on the free speeds of the German autobahns. I could only do some 200 km (120 miles) with a tank of gas having average speed at 168 km/h while Jouko still had gas left in his tank for another 70 - 80 km. This also speaks for your point #4 with the remark that when speed doubles the wind resitance quadruples...

Best regards

Ari "the Farkle-Freak-Finn" Ignatius

Hyvinkää, Finland
2004 ('05) LT, Dark Graphite, "Sunset Cruiser II"

Bike trip from Finland to USA:

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


Pictures of various farkle projects:

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
pozo_izquierdo is offline  
post #22 of 35 Old Feb 26th, 2007, 3:08 pm
Senior Member
 
tomandmelanie's Avatar
 
Join Date: Sep 2006
Location: Manteca, CA, USA
Posts: 117
LT & 4th Gear

I bought a used 02 LT with 14K on it. We ride a lot of twisty canyons here in Northern Calif and I was mostly in 3rd and sometimes in 4th only hitting 5th on longer straights and on the highway. At 18K along with a bunch of other work I changed the air filter to a K&N and put in NGK Iridium plugs. To my surprise the bike really came to life and has improved power at all rpm's after the iridium plugs and K&N air filter. Twisty canyons are now 3rd & 4th and I actually hit 5th in some of the straights. Other LT riders have reported similar power improvements with the air filter change. Now I average 43.6 mpg with a passenger riding mostly back roads up from 37mpg.

I also changed the shocks to Ohlin, your ability to hold speed through corners will also result in some fuel improvement because you slow less into turns and accelerate less exiting. If your bikes handling is sloppy this will help, if your bike feels good just do the plugs and air filter.
tomandmelanie is offline  
post #23 of 35 Old Feb 27th, 2007, 9:12 am
Senior Member
 
Bob204bc's Avatar
 
Join Date: Mar 2004
Location: Newport News, VA, USA
Posts: 189
Quote:
Originally Posted by little_jake
Were do you go in VA to get thin air? Mt Elliot Knob? :-)
Hot, humid air is thin air. Cold, relatively dry, air is thick.

It's all about density altitude.

Bob Chapman
Virginia
2000 K12LT
1978 CB750A (Automatic Cafe Racer Ratbike)
Bob204bc is offline  
post #24 of 35 Old Feb 27th, 2007, 11:34 am
 
Join Date: Apr 2004
Posts: 207
air density

you might want to ck this out...
http://www.usatoday.com/weather/wdensity.htm
little_jake
little_jake is offline  
post #25 of 35 Old Feb 27th, 2007, 1:34 pm
Lifetime Supporter
 
bblalock's Avatar
 
Join Date: Nov 2003
Location: Swansboro(area), NC, USA
Posts: 650
Cool

I'm on the coast of NC so above 45 I'm in 5th gear. Above 55 mph I do not shift down to pass unless it looks tight. Twisties in the mountains normally 4th is fine. I expect 46-47 mpg as an average. I love running up through the gears but don't see running in 4th constantly. 115 hp can handle it!

Benton Blalock
"I ride.....the bike doesn't"

'18 Honda Africa Twin Adventure SportDCT
'12 Kawi KLR 650 "Dirty" - traded in
'08 LT Black "Fireball" 113,000+ miles(RIP- transmission - may be seen on the road again)
'05 LT Yeller er Gold? "Ophelia"(RIP- fire) 80,000 miles
'04 R12CLC (RIP- hurricane) 36,000 miles
230,000+ BMW miles
'Rounder'
bblalock is offline  
post #26 of 35 Old Feb 27th, 2007, 3:57 pm
Senior Member
 
petevandyke's Avatar
 
Join Date: Jun 2006
Location: Dallas, TX, USA
Posts: 1,741
Lucy, you got some 'splainin to do...

OK, 60 mph (indicated on speedo) in 4th gear, 3,500 RPM...5th gear, 3,000 RPM.

Same bike ('04 LT), all conditions equal, bla bla bla.

I am not the dumbest guy on this forum, but pretty close, but it certainly seems that there's no way that the fuel injection system is making that many corrections that an extra 500 firings per minute are NOT going to have an adverse effect on gas mileage.



Soooooo, I did my own quasi-scientific test yesterday.

Ten-mile, multi-direction loop so that wind was not a factor (some INTO the wind, some with the wind), windshield in the same position, full tank of gas--total test involved 20 miles, so the weight difference from start to finish was less than 4 pounds.

Ran the "loop" back and forth on a winding section of Texas 121 north of Dallas, which included four complete stops, twice. Stops did NOT involve engine-braking downshifts (Clutch in, front and rear braking, multiple downshifting to first gear at the end only). Acceleration was moderate but not overly-aggressive--as "equal" a rate of acceleration each time as I could manage, with shift points coming at 4,500 RPM. Speedo indicated 60MPH--activated the cruise.

First ten-mile "loop" stayed in fourth gear. "Computer" registered 44.2 MPG at the end.

(yes I know it's not entirely accurate, but when comparing it against loop two below, it is COMPLETELY accurate, because we're not discussing "did he get precisely 44.2 MPG?" we're discussing, "was there a difference when he did the same loop, under the same conditions, in fifth gear?")

Second loop, no adjustments to anything, even very conscious of my seating and body position, this time fifth gear, activating cruise at speedo-indicated 60 mph. Ten-mile loop returned 50.1 MPG on the "computer."

Or, roughly 13% difference (increase by using 5th gear instead of remaining in fourth) in indicated MPG at 60 mph.

I ride with the ball of my foot on the "pegs" and almost always cover the clutch and brake when in motion, and have practiced dilligently to engrain a quick and very fast downshift from 5th to 4th (including rpm-matching throttle "blip"), so the benefit of being in 4th gear at "legal" highway speeds which would keep one more in the torque and horsepower "power zone" is not a concern for me---if I need it, I know that through practice I have developed the skill to jump down in gear and into the "sweet zone."

I have neither the time nor the dedication to repeat the same thing at 50, 55, 65, 70, 75, 80, with the brown wire connected vs disconnected, with 89 octane vs 91, or any of the other variables, just wanted to settle MY personal curiosity and for me, this did it.

Anyone want to take the torch at this point and do additional "field testing," this could become very interesting (and FUN) to read...


two cents


Pete

========================================
When life throws you a curve, LEAN INTO IT!!!
2000 R1100RT-P...R.I.P. "Old motorcycle"
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

2004 K1200LT "Lick and Tickle"
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


FU*K Cancer. If I have one more MRI, I'll stick to the refrigerator door.

Last edited by petevandyke; Feb 27th, 2007 at 4:00 pm. Reason: typo
petevandyke is offline  
post #27 of 35 Old Feb 27th, 2007, 4:39 pm
Senior Member
 
Join Date: Apr 2002
Posts: 14,436
Ain't that why they call 5th gear overdrive??? And isn't overdrive s'posed to be fuel efficient? Fewer engine rpms means less fuel can get in the front door and out the back? I dunno, butt my '55 T-Bird definitely shows a marked difference in fuel usage when not in overdrive vs when in. Course either way ain't worth a spit on mpg, butt there is a difference!! I just love hearing them twice-pipes with Glass Paks!!
Dick is offline  
post #28 of 35 Old Feb 28th, 2007, 6:35 pm Thread Starter
Senior Member
 
BlackBMW's Avatar
 
Join Date: Dec 2005
Location: Delray Beach, Florida, USA
Posts: 188
Interesting Follow-Up

With the terrible gas mileage I was experiencing (low to mid 30's, about 175 miles per tankful), I brought the LT in to my local BMW dealer. They noted the sputtering and smoking.... put it on the diagnostics and it returned codes that I have a bad oxygen sensor. Also discovered fouled plugs (as I expected) and a dirty air filter. Once the new plugs and air filter installed, diagnostics still show codes for faulty 0-2 sensor.

So replaced the 0-2 sensor and dealer reports it to be running smoothly without smoke.

Hoping this is the end of the story. Of course, here in the "snowbelt" (Denver, CO) we are getting another 4-6 inches so I won't be able to test the gas mileage for some time.

I will report if the gas mileage improves when I can. Undoubtedly, I will use more 5th gear at higher RPMs to see what impact that has.

Mike M

2007 K1200GT Dark Graphite

Last edited by BlackBMW; Feb 28th, 2007 at 6:41 pm.
BlackBMW is offline  
post #29 of 35 Old Mar 30th, 2007, 2:26 am
Senior Member
 
Join Date: Aug 2002
Location: Shoreline, WA, USA
Posts: 495
Thumbs up Other Controls

Hey RetiredJJ

If you are going to put a Manifold Pressure gauge on your bike then I want a combo EGT / CHT with manual mixture control. Heck with the computer!!

That way I can lean to 100 degrees on the lean side of peak EGT. That would give you the best mileage and power me thinks.

Note old school use to be 100 degrees on the rich side of peak for thermal cooling and power but who knows now I see all kinds of charts and opinions on engine fuel management.

Dave you can chime in here for you are the resident engine expert. I bow to your engineering expertise.

Later

Steve A
stevea2980 is offline  
post #30 of 35 Old Mar 30th, 2007, 7:55 am
 
Join Date: Feb 2007
Posts: 142
milage

Went for a ride last weekend. 180 miles averaged 54 mpg on my 06. ran hwy, town & hills. Beats the heck out of my VTX that gets 35 - 38 on a good day.
ferggie is offline  
post #31 of 35 Old Mar 30th, 2007, 8:21 am
Senior Member
 
Join Date: Jun 2006
Location: mount airy (mayberry), NC,
Posts: 1,155
Last Sunday, coming home from teaching in Statesville NC, I avg'd 42-something at 75 mph avg. Rolling hills and such on the interstate. When I left the interstate to get to house, reset and avg'd around 50 mpg at various speeds under 60 mph for around 20 miles.

This bike is so much better "down low" than my Vstrom was. I can be in 5th at 2500 rpm and it will still pull. The Vstrom wouldn't do low rpm in any gear but first or second without bucking.

Randy
rando is offline  
post #32 of 35 Old Mar 30th, 2007, 12:07 pm Thread Starter
Senior Member
 
BlackBMW's Avatar
 
Join Date: Dec 2005
Location: Delray Beach, Florida, USA
Posts: 188
Quote:
Originally Posted by BlackBMW
I will report if the gas mileage improves when I can. Undoubtedly, I will use more 5th gear at higher RPMs to see what impact that has.
Indeed, the mileage has rebounded with the 0-2 sensor replacement. As mentioned, at the same time I replaced the air filter with a K&N. Now getting mid to upper 40's mpg (at altitude).

Mike M

2007 K1200GT Dark Graphite
BlackBMW is offline  
post #33 of 35 Old Mar 30th, 2007, 1:46 pm
Senior Member
 
Join Date: Apr 2002
Location: , ,
Posts: 163
Smile Gas Mileage vs. gear

Might try this test. Maintain the same throttle position, and shift between 4th and 5th and back. The gear that provides the most speed will also provide the best gas mileage. (Remember not to change the throttle.)

Karl
nocanpickem is offline  
post #34 of 35 Old Mar 30th, 2007, 3:24 pm
Senior Member
 
Join Date: Aug 2005
Location: Blossvale, NY, USA
Posts: 577
what impact if any

will the, (would the) break-in style of the engine have on fuel usage?

This site http://www.mototuneusa.com/break_in_secrets.htm points out the possibility that it has a lot.

has anyone had the experience of testing this on two new bikes? What did you find?

Toby in New York
1983 R80RT Red (sold)
'03 R1200CLC (T-boned and replaced with)
'04 R1200CL Sidestand problem, BMW traded me for
'05 K1200LT. Goldie, Priceless
Lusting after K1600 GTL
tobiwan is offline  
post #35 of 35 Old Mar 30th, 2007, 8:42 pm
 
Join Date: Nov 2002
Posts: 348
Fuel

Quote:
Originally Posted by dshealey
Been right here, most every day.

Actually, fuel usage is not all that related to RPM, but instead POWER usage. In any given set of circumstances the bike needs a given amount of power at any one time. It is all thermodynamics, BTU in the fuel converted to Power output. If in a lower gear where the cylinders are firing more often you have the throttle more closed than if in a higher gear, thus burning less fuel each crank rotation. Basically, for any given power output you use nearly the same amount of fuel no matter which gear you are in. However, the engine's efficiency changes over the RPM range, so one would have to develop efficiency curves based on the torque/HP curves along with a fuel usage curve imposed on them. Then at any given instant you could see which would be the best gear to be in. As long as kept within the flatter part of the HP curves though, the gear selected has only minor affect on fuel usage.
Two things missing here: 1. Engine Pumping loses. 2. Engine Friction losses. I went out and ran a real-world test after this thread started, using cruise control, Bike computer reset, and a steady 55 actual mph. I got 5th gear=60 mpg, 3rd gear=40 mpg. I replicated the results twice.
HarvRead is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the BMW Luxury Touring Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Fuel Gauge continuing problems JOHNF K1200LT 18 Jul 14th, 2009 10:32 am
Fuel Cell Installation Questions MolenaarD K1200LT 16 Nov 16th, 2006 12:34 pm
BMW Statement on E85 fuel eljeffe Bike Talk 5 Sep 8th, 2006 1:56 pm
99 fuel tank removal questions jimbeard K1200LT 4 Jun 25th, 2006 10:16 am
Triple BBG-Ride Report murray Ride Tales 8 Nov 20th, 2005 7:34 pm

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome