1200GS Exhaust - Opinioins please

Discussion in 'GS Boxers' started by sauce25, Aug 13, 2009.

  1. sauce25

    sauce25 Been here awhile

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    I did a search and did not get much for threads on aftermarket exhausts for the GS.

    My question is which one do you have and do you like it? I like the Akra and Remus which seem to be the most popular.

    Also have any of you had to remap the Fuel Injection (add fuel) when adding the slip-on. Did you use a Power Commander? I have owned several FI and carb bikes and they all needed to be rejetted or remapped when even just a slip on was added. Without remapping it backfired on decel a lot and just ran lean. The BMW dealer told me that the bike will compensate for the slip-on. Because of past experiences I just don't believe him. None of the FI bikes I have owned have ever been able to compensate for that much more fuel to make the popping on deceleration go away which is a text book sign of a lean condition. Thanks in advanced for you help.

    sauce
    #1
  2. Das Boot

    Das Boot down periscope

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    Best of luck
    #2
  3. BobMCP

    BobMCP Limey Adventurer

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    You must have misspelled exhaust if you didn't get much info here with your search.
    I have a Staintune/Remus Y-Pipe setup and like the result, you will not see much HP gain on the GS, but the improved throttle response and sound made it a worth while mod for me, but I am sure others may disagree.
    I do have some decel pop and I am considering a Power Commander and Dyno Tune at some point, it does run quite well as is but I have had other bikes PC/Dyno Tuned to remove the slight imperfections in the FI Mapping and think this also is worth doing.
    #3
  4. Throttlerocker!

    Throttlerocker! Giddy up go

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    I went with the Keihan headers and Staintune endcan. Both work well together, they were $539 (can) from ca-cycleworks.com and $490 for the headers with a 10 year warranty with the crossover pipe and O2 ports (original diameter too) from keihan.co.uk delivered. I also bought the larger intake snorkel (wunderlich item-Nippy Normans or Santa Cruz) and a hi flow air filter from BMW of Atlanta. Oh yeah and a Dobeck fuelbox from customdynamics.com for $249 delivered. Everything together did the complete job. No surging and smooth rideability with a nice improvement down low (under 4200 rpm) and above 4200 well lets just say It woke the sleeping beast up nicely. :jump
    You could try just the header and the fuelbox to start, then as money allows......
    The bike sounds nice (not to loud under 4200) and sweet in the upper rrrr's!!!!!
    #4
  5. tmex

    tmex Long timer

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    I have the Remus on my 12GS and it does save substantial weight, but does virtually nothing for the performance (which I expected) or the sound (which is dissappointing). The Akra on my F8 does nothing for performance either, but I do love the sound. Nothing beats the sound of the Akra IMO except perhaps the Termignoni's on a Ducati.
    #5
  6. SCQTT

    SCQTT Zwei Kolben

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    You can save a few pounds, but you are not going to get much more in the way of HP unless you toss huge money at it.

    Even stock they have a lean pop on closed throttle deceleration. It is only going to get more pronunced with a more open pipe.

    They sound like crop dusters to start with? You want that to be louder?

    Stock is cock, just ride the dang thing.
    #6
  7. LTCOliverNorth

    LTCOliverNorth Peeping Tom

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    I picked up a used Staintune from an inmate here for the sole purpose of losing some weight. The can's build quality is great! The can is 4" to 6" longer than stock which does not pose an issue with my TT panniers; if you have tight clearances it's something to consider. It does pop on decel, but it popped on decel just as much with my stock can - only it's louder now :)
    #7
  8. RogerJ

    RogerJ Waypoint Wanderer

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    What Scott said. Also, the back-popping gets worse still if you go to a larger airbox/snorkel mod to put more air through the beast without some concerted tuning efforts.
    #8
  9. Disco Dean

    Disco Dean Long timer

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    I have the Laser system from Holland that I purchased at DualSport Plus here in Ontario.

    First - no back popping issues for me - no more or less at all with this system.

    I like it a lot - savings of about 11lbs which is good for about 1.5 hp in weight. With the homologated insert it is louder but nice and sounds like a very big 4 stroke motocrosser - I like it. Not too big an increase in power. But - With the competition insert in it is quite loud but still not as bad as a chopper or anywhere near. Power with that insert in is about 5+hp which can be felt - approx 6% or so...

    The finish and materials are top notch - see pics included.

    As stated here before by me and others - there is no way to change the mapping and no need to without a BMW computer - the bike does compensate for the change in the exhaust. that you will have to believe as we have dyno and race bike experience with that here - no matter how hard we tried we could not change the mixture as measured at the exhaust - the bike changed the mapping to suit the increased flow parameters - the only way to do that is with a comp - but it stayed the SAME as stock with changes to exhuast and also to the airbox etc.

    For what it is worth the reason I chose the Laser is because it has the cross over tube and while it does not change the performance in my experience it does help balance out the exhaust and contribute it to being a bit smoother.

    - I also like the springs - segmented assembly as it allows for a bit more precise fit and I just like the springs.

    Price was good and on the lower side of the remus and much cheaper than the Akro.

    I have noticed a few interesting things.

    One of which (3000km on the exhaust and 40k on the bike) Fuel Mileage !!!! has gone down strangely enough - it is better by about 3.5% - I totally did not expect that one. And, I even think I am riding it harder to hear the stupid thing growl :rofl

    Your call - thinking back I think I should have gone for a new GPS and custom seat first but I love the exhaust...

    Dean

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  10. Wallowa

    Wallowa Long timer

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    Hey Dean,

    What was the cost as we see it on your bike and do you have the Hp and Torque curves with and without the system? Thanks..
    #10
  11. sauce25

    sauce25 Been here awhile

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    I just tried it again and nothing specific to my question. Try it nowÂ…none that come up have exhaust in the title. This thread comes up though! :lol3

    I think you will benefit from the Power Comander.
    #11
  12. sauce25

    sauce25 Been here awhile

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    Thanks for the reply's. I do want a louder pipe as well. You all agree that the AKRA is louder? And sounds pretty good? After reading you reply's it just confirms my thoughts. Like a few said above it is already backfiring Stock, how is it going to get better by adding more air and no fuel!!!
    #12
  13. (sp?)

    (sp?) flaming ahole ;)

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    Here are the dyno run numbers for my R1200GS w/ StainTune slip-on. no mapping changes done, or required (see lambda value)

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    #13
  14. Wallowa

    Wallowa Long timer

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    Where are stock values to compare against? And can you explain the abbreviations [I see torque and Hp]? Again..just me ..but I have only seen these based on RPM not mph.. Thanks!
    #14
  15. (sp?)

    (sp?) flaming ahole ;)

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    STP - standard temperature and pressure, e.g. a value corrected for temperature and altitude.

    these runs were taken one evening after JohnJen, Javarilla and I had just done OVADs on our bikes. I don't have the stock data but do have an RPM correlated graph.

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    #15
  16. Wallowa

    Wallowa Long timer

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    Once upon a time I lusted after a R1200S...had a special order in with BMW...desposited $1,000...waited three months for delivery..then was told that BMW had cancelled all special R1200S orders since there were too many in inventory....Dealer was great and had no real part in it; BMW never hinted they were going to cancel... Dealer gave me my $1,000 back...I turned around and bought my '07GSA...in my opinion a much better bike than the S for me...

    OK...long way around for these points...while researching my R1200S I got heavy into adding an after market exhaust...here is what I found:

    #1 Very expensive; very,very expensive

    #2 Perhaps a slight 3-4 Hp increase at higher Rpms

    #3 The torque curve had a flat spot relative to stock in mid-Rpm range [see above]


    So for a sports bike it was a toss up...for a GS or GSA used off road it was not what I personally want...why:

    #1 I have all the Hp and torque that I could want or use

    #2 The torque I wanted was in mid-range not at higher Rpms

    Soooooo....I have found that exhaust systems, ignition mods, fuel control mods are only of benefit if they fit your special needs...discussing them is like discussing which oil is best! Lots of opinions..

    If you want to put on a cool looking and sounding exhaust...go for it, it is your bike, do with it what you want to...

    Dean's Hp vs weight is a good one; on a race bike this would make sense..... weight is especially of interest for me when that weight is carried up high above CG, where the muffler is mounted.....but I have just shed 27 pounds of weight by going to soft luggage [Ortlieb] and benching my BMW aluminum "adv" boxes..and again I have got way more Hp/torque that I could ever need or learn to use...but reducing weight and especially wt. above the CG will accelerate the development of my riding skills...skilled riders of GSAs can carry a huge load and still make the bike dance under control over tough off road terrain...I can't yet but that is my goal.

    If you can overlay the stock vs custom exhausts curves...most manufacturers have this on their web sites, but doing your own dyno test has more validity...check out where and when the advertised advantages occur compare that to where and when you most frequently use the Hp/Tq.

    To paraphrase a producer of off road riding skill training DVDs "the best accessory you can add to your bike to improve your skills is gasoline" :wink:

    Ps...You measure torque and calculate Hp from that @ Rpms...torque rules!
    #16
  17. SCQTT

    SCQTT Zwei Kolben

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    You do know that the engine configuration and not the "pipe" is what makes the bikes sound the way they do. Right?

    Most people want their bike to typically sound like one of three engine configurations.

    a 45 degree V twin with a single crankpin.

    A 90 degree V twin.

    An inline four.

    People tend to make up for the fact that they do not have the "right" engine layout for the optimum sound they are looking for by making their bike louder.

    I'm sorry, I do not mean to insult you if you know all of this, but I am really surprised by how many people do not.
    #17
  18. (sp?)

    (sp?) flaming ahole ;)

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    I wasn't looking for more horsepower (directly). I put the exhaust on it so I could hear the bike. I like to watch the road when I ride and hearing the exhaust allows me to shift the bike better. I didn't want an excessively loud bike and have been happy with StainTune exhausts on previous BMWs. It works as expected and I like it.

    I didn't notice any substantial improvement in HP or Torque. The 5000 rpm dip is there with the stock system also. I liken it to a turbo - get it up above 5K and it takes off. As an extra benefit, the StainTune is much lighter than the stock system.
    #18
  19. Wallowa

    Wallowa Long timer

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    Hey (sp?),

    Like I said before we should do what we personally want to do with our bikes....put on or take off anything that our heart desires..we only have to please ourselves..

    I love to run through mechanical issues to find out exactly what the cause and effect relationships are...in other words the what, why and when.

    My questions and comments about a torque dip or flattening of torque curve were made to compare what happens with most after market exhaust systems on our Boxer motors...the after market exhausts trade off some torque at lower rpm [your charts show the torque decreases about 4,400 rpm and then starts up about a little past 4,800 rpm] for gains at higher rpms....

    If you can find stock Tq/Hp curves you will not see these mid-range torque drops...but if you don't spend much time in that mid-range flat spot it doesn't matter that it is there...blip the throttle, you are past it on the way to higher rpms, the "5,000 rpm" launch you describe is where the torque slope on the stock motor steepens heading toward max torque...but since I ride almost entirely off road, that loss of torque in mid-range could become problematic for me...the even torque grunt off road is what keeps you in control...and linear is better than ups and downs..oh yes, I wear ear plugs and a full helmet, always have, so I shift by the feel of the motor and other mechanical sounds..never have used the exhaust as a cue...but then I don't like the pounding pulses of loud pipes, just my tastes.

    Soooooo...glad you like the sound, the look and the feel...that exhaust system you have is one of the better after market systems and very popular.. enjoy!
    #19
  20. (sp?)

    (sp?) flaming ahole ;)

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    very likely a local minima/maxima of resonance causing back pressure in exhaust flow and up through the intake. the StainTune may have it there. the factory likely has it somewhere else. I play with inserting the silencer (outlet reduction) and find the torque is smoothed out. I suspect it fills in that trough.

    for offroad, I use the black 'n' blusaberg. the GS is simply too big - even though I'm not exactly small at 6'6" and 250 lbs. the 'berg has 3 fuel injection maps. the softest map has the best power delivery for tight trails. the upper two maps are much different and carry a bigger power hit. it has the stock pipe which flows fine and has the advantage of stealth. the only thing you hear is the honk of the airbox - located right between your legs.

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    #20