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Thread: Cat eliminator Y-pipe

  1. #1
    Registered User bmwterrien's Avatar
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    Cat eliminator Y-pipe

    I have a GS and was wondering if it is worthwhile to get the Y-pipe. It is my understanding, one gains better lo/mid range without the cat. I keep the stock muffler. Any thoughts and/or recommendations about this ?

    TIA
    Steve
    Steve Terrien

    BMWMOA #18114

    BMWMOV

  2. #2
    Registered User chickenman_26's Avatar
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    Hi Steve,
    I'm sure this isn't what you're looking for, but...
    No personal insult intended.

    Thoughts

    Some bikes are essentially factory race bikes sold with street exhausts, and those can benefit from being uncorked. But most street bikes' engines are in a state of tune such that exhaust mods alone do little if anything. Aside from that, I assume you know that these things are "for racing and off-road use only." Removing a catalyst from a street bike is illegal. Even if it did provide a slight gain at low & mid range, it may create a slight loss somewhere else on the torque/hp curve or result in drivability problems. The only way to find out is with baseline and post-mod dyno data for your particular bike, but seat-of-the-pants data from "satisfied customers" is what's normally available. They spend the money and will not be dissuaded from believing they got their money's worth. The idea of getting something for nothing has strong appeal. And don't necessarily believe manufacturers dyno data; those tests are often manipulated to show what the manufacturer claims. "Your results may vary."

    Recommendations
    If your bike has a performance glitch, get it corrected. If not, leave it alone and just enjoy it. For most of us, rider education and practice is the most cost-effective performance mod.

  3. #3
    Megalodon fish's Avatar
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    Re: Cat eliminator Y-pipe

    Originally posted by bmwterrien
    I have a GS and was wondering if it is worthwhile to get the Y-pipe. It is my understanding, one gains better lo/mid range without the cat. I keep the stock muffler. Any thoughts and/or recommendations about this ?

    TIA
    Steve

    Sure it's worthwhile, just make sure you have realistic expectations. Don't expect much performance improvement, but do expect to lose about 13lbs (cat only, IIRC), not have your feet roast in the summer, and gain a nasty bark.

    Gotta echo Eric...seal the joints VERY well or the backfires will scare the heck out of you.
    "No one wants advice -- only corroboration." -John Steinbeck

    Like San Jose BMW Motorcycles on Facebook.

  4. #4
    Bud
    Guest

    Cool Y pipe

    I have been thinking about the same thing and so researched it a little. I agree about the performance remarks. I'm not looking for performance just want to shed 13 pounds and unwanted heat off the darn thing. I agree that it might be illegal to take it off but if I were you I would keep the cat and put it back on if you sell it. Anyway the cat looks like crap and detracts from the looks of the BMW IMHO.

    Sebring makes a Y for the GS that fits the R but these are pricey at about $300. Nice thing is that they bolt right up and have a stop for the center stand. Eurotech sells them. Good luck.

  5. #5
    Jim Bud
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    Y pipe on the 1150GS

    Hi Steve, I have gone through that "upgrade" over the last year. I've now put about 12,000 miles on the bike since then and I am now happy with the changes, but only after I added a Techlusion R259 controller to the bike.

    As some background, even after doing a very good job of tuning up the bike (myself of course) I continued to experience minor surging and the Y-pipe did nothing to improve it, maybe made it worse. I tried adjusting the throttle position sensor to "richen the mixture" and it worked, the surging was gone, but the gas mileage went in the tank. I still wasn't satified and decided that there must be a beter way.

    After reviewing options, I decided to add the Techlusion R259, and this baby really works. The unit is set up to really force all of the performance that "more" fuel can bring to this engine; but there is also the the abiity to "fine tune" the when and how much more portion of the equation. I have tweeked it, after following the directions and talking to the tech. at the company and I am now, very very happy with the outcome. The bike is now very smooth and very responsive and gives good mileage too.

    It has never run so good.

    I thought this would be of some help to you.

    Oh, yes, hang in there Spring will come

    JIm Bud
    YB West
    Jim Bud...

  6. #6
    going mobile 100981's Avatar
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    I've been thinking of replacing the cat with a y-pipe. I am more concerned with the heat the thing is generating under the transmission/engine than with gaining a hp or two.

    I notice the new BMWs are moving the cat to the rear, away from trans/engine.

    Is the heat that the cat generates a concern or would removing the cat be a waste of time and money?

    As far as legal/enviromental concerns I really don't give much weight to it considering large trucks etc. are not required to comply. I don't think my 1130cc engine is a major point source for pollution. Besides, I live just downwind of the biggest mercury emitting powerplant in the state (Keystone Generating Station), so let's keep it in perspective.

  7. #7
    Jim Bud
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    Y-pipe

    While I have done the conversion, I would not do it just for the heat reduction; unless maybe you spend all of your time in stop and go traffic in the summer...I'm sure it makes a difference, but it can't be that great, because the whole engine in between your legs anyway...if engine heat effects are you concern, just run synthetic oil and don't worry about it....of course, being out here inthe West and riding in the desert, I do that too.


    Cheers
    Jim Bud...

  8. #8
    CustomSarge
    Guest

    Thumbs up Dogs hate cats

    For completely different reasons, I had to "take the cat out". Kbasa posted a (really quite good) picture of it, showing the exhaust system clearly in "Tech/Kbike/TripleClampInterchange".
    So 1> yes it now has a GREAT bark if you rap it.
    2> in removing the cat, the O2 sensor has to be dealt with. I put a potentiometer w/upside resistor as a replacement. It allows "dial-a-mix" and surging isn't possible, since there is no O2-to-injector control loop. BMW does a lot of things Very Well, but I've seen evidence of electronic designs (i.e. ABS initialization, engine management underdamping/overgain) that show they're mortal. It's a shame that the Techlusion device has to exist. Those folks did their homework, I spoke to one of the engineers @ WV Nat'l, BMW should subcontract them.
    3> if your state has exhaust emission inspections, DON'T DO IT unless it's reversible for inspection time! Here in MI, if we remove a cat and get caught (no inspect state, but they check muffler shops) it's a fine for us & the owner of $5k each!

    P.S. The exhaust on the R11HR will take a broom handle until the curve at the Y, ergo the bark.

  9. #9
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    Wow.... this site rocks! Y'all got guys over here who really know their stuff..... I'm afraid I don't.

    That having been said, without going into the history of my experimenting with a few configurations..... if your willing to spend the time and the money, you might be able to better BMW at their own factory design.

    I'm currently running a K&N, Remus "Race" Y-pipe, and Super Trapp with 14 internal disks. It's given me increased horsepower, less heat at my ankles & trani', and a pretty impressive flat torque curve! SOUNDS GOOD TOO!

    Other configurations have given me an increase at top-end, but the surge was bothersome. Believe it or not, my best results have been with the cat' converter remaining on the bike: I had the K&N in place and put a straight-through muffler whose baffling was burned out. This set-up kicked butt, but made little noise (I like noise). I've even run with nothing on the end of the converter..... works great in the winter when the air is cooler, but it's lotsa fun in the heat of summer throughout it's mid-range! It's low-end and upper-end suffers though.

    Buy a used can with the least amount of back pressure & strip it of any packing, put it on the end of the cat' converter, and substitute the stock air filter for a K&N. It's then quick-n-easy to put the factory can on there if need be.........

  10. #10
    SniggletyFidget syeager's Avatar
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    Yeah, but...


  11. #11
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    Quote Originally Posted by fish View Post
    Sure it's worthwhile, just make sure you have realistic expectations. Don't expect much performance improvement, but do expect to lose about 13lbs (cat only, IIRC), not have your feet roast in the summer, and gain a nasty bark.

    Gotta echo Eric...seal the joints VERY well or the backfires will scare the heck out of you.
    Did you use anything other than the clamps to seal the joints? I saw elsewhere that an anti-seize product is highly recommended. Not sure if that does anything to add to the seal.

    Thanks

  12. #12
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    anti-seize won't seal any leaks, it keeps heated/cooled metals from getting stuck together.
    i have a Laser system (cat elim and cans) on my R11S, have never used any sealant on it.
    Ride Safe, Ride Lots

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