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Thread: K11 vs K12

  1. #1
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    K11 vs K12

    Is there much mpg difference between a K12RS and a K11RS? We're talking interstate speeds.

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    '96 K11RS. 45 - 47 mpg depending on quality of gas and wind direction. YMMV.

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    Registered User LSkrabut's Avatar
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    2003 K1200RS with a large Parabellum windshield, side bags and Givi V46 tail bag.

    I was getting 42-46 mpg at interstate speeds (70-80 mph) with ECU 166 install.

    Installed a ECU 296 and my mileage has improved to 46-50 mpg at interstate speeds.

    This is at 5000' and higher. I feel I get better mileage but less power at these elevations then when I do drop down to lower elevations.

    ECU 296 was the last version used by BMW and the 166 version has a cold hesitation issue among other minor updates.
    Larry S
    Utah driven
    2003 K1200RS
    1988 K100 LT

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    K11 vs K12

    Don't know if there is still any interest in this thread, given it's date, but I'll weigh in anyway.
    I love K11s, especially the K11RSs. Owned probably 5 of them, along with a K100RS. I think they represent a great era of fast, "modern" bikes that perform to this day with no excuses (unlike airheads). And their technology for the most part is not so advanced as to make them garage-unfriendly.
    I now ride a 2003 K12RS. I love the smoothness, and I suppose I use the added power, though the K11s never felt lacking to me.
    The K12 definitely used more fuel. My K11s used to return 45 MPG on average, and I could hit rarely hit 50 if I kept to the speed limits and found non-ethanol fuel. The K12 will not get to 40 MPG, averaging around 38. Now that engine smoothness may have me cruising faster, but I refuse to believe guys are getting upper 40's from a K12RS, unless they REALLY ride slowly. I don't do jackrabbit starts, I rarely use the top half of the RPM band (shift at ~5000rpm), pride myself on my smoothness, but I do run with the faster cars on the freeway; typically running 75-80 MPH.
    The K12 handles the engine heat better. K11s toss it right on your legs, and the tank gets hot.
    My big complaints about the K12 is that because of the higher fuel consumption, it doesn't have very good range. At less than 40 MPG, you are going to be forced to stop for gas before 200 miles, given the 5.2 gallon tank. BMW really should have increased capacity.
    The other problem is the oft-mentioned left-side hardbag. The upswept pipe makes that bag half the size it should be, and precludes its holding a helmet, or much else for that matter.
    So the K1200RS excells at eating up state lines with its smoothness and power, except you have to stop more often and can't carry as much. Add in their simplicity and the K11s look real appealing.

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    Registered User 58058D's Avatar
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    Interesting read about the K12RS getting routinely below 40 mpg. If I was experiencing that, I would feel I have issues to address. I also ride smooth, but aggressively. With over 128,000 on this bike, the only times I have gotten less than 40 were either at the track (32 mpg) or pretending I was at the track and shoulda been arrested. On long freeway jaunts with very steady speed of 70 mph, I have attained 47 mpg. I routinely get 42-44 on the 1200RS with a Rhinewest Cam gear and chip set. I get the same mileage on my K1300S doing the same weekly commute from Mendocino to Sacramento, mostly twisty fun riding with about 20 miles of freeway out of 185 miles. I routinely got the same mileage when I commuted from Fiddletown to Sac and back daily on the 1200RS. On my K1100RS, I routinely got 43-45 for that ride over a 2 year period before trading it for the K1200RS and like the previous poster, I could hit 50 if cautious - once hit 57 but always wondered if that was a math error. I rarely ride the K12RS anymore, but when I do I get the same 42-44 mpg, any variation dependent solely on my wrist.
    Last edited by 58058D; 09-20-2012 at 12:09 AM.
    Jim Douglas '00 K1200RS >132,000 miles my primary bike again,
    Gone: '09 K1300S sold @ 22k mi, '93 K1100RS traded @ 78k mi, '85 K100RS sold @ 44k mi
    '06 Kaw 650R track bike sold
    http://www.seagullbb.com/

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    K12 vs K11

    Interesting data points, Richard. Thanks for posting.
    You do realize that most BMW speedos are rather optomisitic? GPS tells me that at an indicated 70MPH I'm really doing 66. Our K12 mileage differences might just come down to the fact that I rarely run that slowly. Interstates around here move at about 75 MPH in the passing lane, and I typically run just over the high end of that; an indicated 80 MPH +.
    I would be tempted to look for a mileage solution were it not for the fact that other K12RS owners I've spoken with report the same sort of numbers.
    If you can get 40+ out of your yours, I'm jealous, but still not willing to slow down that much.

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    Sorry, Jim, I misnamed you!

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    Registered User LSkrabut's Avatar
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    Well now, I invite you to come to Utah and lets take a ride or two for checking MPG's against some very enjoyable roads.

    While I am not a jackrabbit starter, nor a rider who punches the throttle for the thrill of it. I certainly do not ride slow by any means. I usually go about 3-9 mph faster than posted and willing to hit 90's if the situation needs it to pass a car or truck. Our interstates are posted mostly at 75, 65 in some towns, and 80mph on the open areas in central Utah. 2 lane roads are posted at 65mph.

    I also measured my odometer and speedometer with my mounted Zumo 660 a lot. I tend to do math often while riding. For the odometer, over 200 miles it is off, about 1.3 miles fast on new tires. Speedo is also off, with new PR3's 73 indicated for 70 and worn 74ish for 70mph. Close enough for government work as I call it.

    True only gotten my '03 KRS in March, but I have already put on 17k miles. While I still have my '88 K100LT, it never gotten the mileage my KRS gets. Checked with the same Zumo for 60k enjoy miles in less than 4 years of riding it. True, the GPS might be off, but I doubt it.

    Normal low level fuel lamp does come on, usually around 205 to 215 miles and I put in about 4.3 to 4.4 gallons. I commute daily the same 120 mile round trip, mostly on interstates. So what I report is from a pretty consistent rides. Not a single fluke or special case ride. I have had some runs where I only gotten 42 figured and 57 figured out, but I think I knew why I gotten them, hot dogging or I was taking it very easy and going under but steady 60 for a long time. Both times, I count those as being rare.

    Before I found a European ECU with code 296, my mileage was never better then 46.5 mpg and that was rare, again typically I got around 41 to 44 with the 166 ECU. Per the original owner, he stated the typical mileage was from 36 to 40, but he did own other very nice sport bikes and elected to keep those instead of the KRS.

    I guess it does matter on how one ride, where one rides, what one carries and how the bike is farckled out. Speaking of which I got a large windshield and top case, but normally do not carry much other than ATGATT per weather needs.

    Now back to the OP question K11RS vs a K12RS, ride them both, decide which one fits both you and your pocket book. Which one will be easier for YOU to do the maintenance on. One thing I am not enjoying is the changing the tires. I did my own on the K100LT, now on the K1200RS (5.5 rear rim), I can break the bead, but I do not trust myself not to scratch the rim taking the tire off or on. $55 just to change both rims and balance them. I do take the rims off the bike. That part is not bad once one understand what is required to remove to get them off.
    Larry S
    Utah driven
    2003 K1200RS
    1988 K100 LT

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    I may just take you up on that "come ride Utah" offer. Sure would be interesting to resolve the mileage differences.
    Come to think of it, I base my mileage calculations on the bike's odometer readings. If the odo is as far off as the speedo (about 5-6% high) then my true fuel mileage is even worse. If I refill with 160 miles on the odo (I always reset at fill-ups) I know it will take over 4 gallons.
    Low fuel light comes on at about 160 miles, and I rarely risk going 200 without refueling.
    Are you riding at altitude? That thin air may be the answer. I'm at about 250 ft here in New England.
    Enjoy the ride.

  10. #10
    Kbiker BCKRider's Avatar
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    Tony, I think it is the norm for BMW odometers to be very accurate - no more than 1% off and of course that amount changes slightly with tire wear.

    Most (not all) BMW speedos read 7-10% faster than true speed. Certainly my current bike's speedo is quite "optimistic." Strangely, my previous K75 seemed to be dead on. At 60 mph, each mileage marker on US highways was crossed at the same second a minute later. I've read that police BMW's also have very accurate speedometers!
    Doug
    1992 K100RS

  11. #11
    Registered User LSkrabut's Avatar
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    I do feel that the elevation does play in the mileage game. But also how one rides or drives. I rarely have been down low in elevation on a bike (3k or lower), so I really do not know what my KRS will get in mileage at sea level with my riding style. At the same time power is down some at the higher elevations, but with the KRS, hardly noticeable to me with my riding style. I go for long, mile eating rides more than power and exhilarating rides.

    Tony, do you know what ECU your KRS has in it? As I stated, when I replaced my ECU from a 166 to 296 coding, I did pick up a noticeable improvement of fuel mileage.

    I did take a long interstate ride the other day combined with back roads coming home, parts were marked at 80mph and running around 83mph per GPS, My mileage did dip to 43.6 for that fuel segment. My low fuel lamp did come on around 189 miles and when I fueled up at 202 miles, I put in about 4.63 gallons of premium (10% ethanol). Other segments I went back up to mid 47.3mpg and 48.6mpg, but my speeds were more in the 65mph (GPS) range for the most part. For me it does really matter on how one drives, the type and speed one drives. Another trip 2 days later, one segment I gotten an almost unbelievable math of 53.2mpg, but that run took me up over 10k and speeds more around 40-60mph for the most part of a 165 mile run. I was enjoying the fall beauty

    Amount of stopÔÇÖs and goÔÇÖs that occur, length of runs between fuel upÔÇÖs and how one fuels up all comes into play with MPG reports. I feel to respond to a statement of what oneÔÇÖs fuel mileage is, the results need to be taken over a rather large sampling, and consistence is needed by the person to have a good understanding of what oneÔÇÖs mileage is on a vehicle. Understanding of the metrics used for making these statements. Items like using GPS now days, balancing with the odometer readings and freshness of the rear tire (diameter of the tire with odometer consideration) all come into play.

    Anyway, anyone want to co-ride in Utah, If I am available, just ask. Time to head out in the mid 30's to see more mountains and valleys before the snow starts to fall.
    Larry S
    Utah driven
    2003 K1200RS
    1988 K100 LT

  12. #12
    Registered User 58058D's Avatar
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    Just getting back to this....TonyCarlos, no problem on the name. Yes, I do know about the speedos (nearly 250k on BMWs, so I have that down....;-) ) We have lots of the speed signs around with the radar display of 'actual' and mine is off by about the same as yours.
    { sidebar: Though most K odo's I am aware of are reallly accurate regardless of the speedo, in setting numerous Poker Run routes, we used BMWs of all styles so that we could more accurately guage what mile point a turn would be at for each style. We had a couple K's (back in my 1100RS days), a couple oil-heads a couple airhead GSs and one Ducati. I think the Duc was sort of between the Ks and the airheads with the oilheads sort of there too. But there could be a 10% difference in mileage between the K and the airhead GSs. }
    If you (TonyCarlos) are running at the speeds you say with the larger screen, I am sure that would account for a big part of the difference. Since F=MA or (mv^2)/2 the difference in wind resistance for a 10-15 mph spread would be substantial. I see that the manual says for steady state that the difference is indeed substantial. According to the manual, at 90km/h or 56mph, est 47.9 mpg (matches my rare steady state though at 70 real mph) , while at 120 km/h or 75 mph it drops to 40.5 mpg. Since I am probably averaging 52 mph but far from steady state, that would put me in the right spot. Altitude will come into play as the m part of the equation, less dense air means less resistance - though I have no idea how much the leaner affects our mpg since the mass flow sensor in the EFI accounts for the change.......I never looked into it. So in keeping with the signature/comments of many.......YMMV
    Jim Douglas '00 K1200RS >132,000 miles my primary bike again,
    Gone: '09 K1300S sold @ 22k mi, '93 K1100RS traded @ 78k mi, '85 K100RS sold @ 44k mi
    '06 Kaw 650R track bike sold
    http://www.seagullbb.com/

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    My K12RS is a 2003. Stock in any way that would effect fuel mileage, including the ECU (I don't know the model number, where is it listed?) and the windshield. I always run with the hardbags attached. Tires are Michelin Pilot Road 2s, always inflated to 36 psi front, 42 rear. Mobil 1 15W-50 in the crankcase, conventional gear lube with a moly additive in the gearbox and rear end. I weigh about 170 lbs, and run 91 octane fuel.
    My owner's manual says that fuel consumption (in accordance with ISO 7118!) should be 40 MPG at a constant 75 MPH. I figure the factory probably has this maximized, no bags, skinny rider flat on the tank..... So the fact that I am getting 38 MPG in the real world, running at a speed slightly above 75, suggests to me that I'm probably doing about right.
    I've seen automotive studies where the highway mileage was improved by 6.2% in going from sea level to 7300 ft. Anyone running at 10,000 ft would bennefit from reduced fuel being injected (due to less oxygen) as well as less dense air to punch thru. Given how unaerodynamic bikes are (double the Cd of cars), this is probably a large factor at speed.
    I'm going shopping for one of those bicycle speed trial aero-helmets!

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