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Thread: Installing Exhaust Nuts - Encountering Resistance - Help Needed Please

  1. #1
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    Installing Exhaust Nuts - Encountering Resistance - Help Needed Please

    I am installing a Keihan system on my 86 R80. Back to dual mufflers from a 2-into-1 system that was on when I bought the bike.
    OK; so starting hand-turning the exhaust nuts and new compression rings and clamp rings. About 3/4 way to the bottom of threads I'm
    encountering resistance. At this point no more hand-turning. Did not want to put my finned-nut wrench on it though.

    Question: Is the resistance I'm encountering just the point where the compression ring is starting to compress under the torque of
    the clamp ring and finned nut? Compression rings and clamp rings are new and the finned-nuts are in near-perfect condition. No
    bad threads anywhere. In fact, the finned-nuts screw down fine on both jugs to bottoming out.

    What's up please?

  2. #2
    Benchwrenching PGlaves's Avatar
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    I assume the header is straight tube - no flange on it - right.

    So, you have already threaded the finned nuts to bottom without the compression ring and the threads are fine.

    Are the new compression rings the same size as the old ones?

    If so, you are most likely just feeling the new rings starting to compress.

    I would liberally anti-seize everything and slowly tighten with the wrench. Don'g grab the big wrench way out at the end - use as short a handle as you can to snug things up.
    Paul Glaves - "Big Bend", Texas U.S.A
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    Quote Originally Posted by PGlaves View Post
    I assume the header is straight tube - no flange on it - right.

    So, you have already threaded the finned nuts to bottom without the compression ring and the threads are fine.

    Are the new compression rings the same size as the old ones?

    If so, you are most likely just feeling the new rings starting to compress.

    I would liberally anti-seize everything and slowly tighten with the wrench. Don'g grab the big wrench way out at the end - use as short a handle as you can to snug things up.
    ************************************************** ************************************************** *******************************
    UPDATE: I checked all parts and pieces. I see now the header pipe itself has a slight expansion about 1 1/2" from the start of the header. I think this may be
    the problem and won't let me send the header pipe all the way into the jug............???????

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    Forgot to add; old compression nuts long ago trashed. Parts fm. microfiche so appear to be proper fitment.
    I'll have to see if there are thinner compression nuts for this bike. It's that or the header pipe being expanded
    slightly is not allowing the finned-nuts to tighten all the way down. Using plenty of anti-seize, too.

  5. #5
    Administrator 20774's Avatar
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    It might be a bit of a pain, but you could remove the header pipe and run the finned down by hand and see where it stops turning easily. Then use that for comparison.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

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    Quote Originally Posted by 20774 View Post
    It might be a bit of a pain, but you could remove the header pipe and run the finned down by hand and see where it stops turning easily. Then use that for comparison.
    Thanks Kurt for the tip. Just measured the jug inlet and old pipes and new pipes.
    Seems the difference is the new pipes allow inletting into the jug at 1 3/8"; while the old pipe allowed inletting into the jug at 1 1/2".
    The killer is that 1/8" difference it appears.
    The new header pipes are expanded by a mandrel to approx. 1 1/2" from the start of the inlet into the jug. The old pipes were straight without any expansion. What to do?

    Could a muffler shop compress the expanded header pipe and return it to it's original o.d.? Or, can I just gently tap on the header to send the
    pipe into the head further?
    Last edited by captainmako21; 09-25-2013 at 05:35 PM.

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    #4869 DennisDarrow's Avatar
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    Wondering how much torque one can apply before even CHANCING a problem with the threads? Is the distance of tightening the finned nut on the same wih all the rings and stuff the same without the compression ring and collar?.....In other words just the finned nut......?????????? Really think you would have a hard time getting that diameter shrunk with any kind of machine......lol.....perhaps though, as is likely there are folks out there with LOTS more knowledge and experience than I have on this subject.
    Not wanting to force that nut on; but how much force can one put on it???????.........God bless.......Dennis

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    Benchwrenching PGlaves's Avatar
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    Ah, the joys of the aftermarket device that "should fit" or "almost fits".

    I would: send it back to the vendor if at all possible.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://www.bigbend.net/users/glaves

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    Unhappy

    Thanks Dennis. I don't want to force anything frankly.
    If the new headers had just straight pipes all would be fine.
    Talked to the dealer I bought the Keihan system from and he suggested using a rubber mallet
    to tap the header in. Again, not sure I want to start tapping or hammering on anything.
    Or, start torqueing the nuts down only to do damage to the head....................
    Last edited by captainmako21; 09-25-2013 at 09:31 PM.

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    Quote Originally Posted by PGlaves View Post
    Ah, the joys of the aftermarket device that "should fit" or "almost fits".

    I would: send it back to the vendor if at all possible.
    Amen Brother. Dealer ain't too helpful.

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    Registered User lmo1131's Avatar
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    +1
    I would: send it back to the vendor if at all possible.
    -1
    the dealer I bought the Keihan system from and he suggested using a rubber mallet
    to tape the header in.
    INSIST on returning the headers.
    "It is what you discover, after you know it all, that counts." _ John Wooden

    Lew Morris
    1973 R75/5 - original owner

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    Registered User godfather's Avatar
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    I have always prescribed to the
    "If it does not fit...DO NOT force it" philosophy.
    Return em ' to the dealer.
    Attitude is everything!
    1978 R100/7
    08' V-Strom 650 great light weight tourer

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    I just put on a new set of Keihin headers and they were not swaged out as you say. Perfect fit. I have heard of some 38mm headers that were swaged to fit the larger 40mm heads. That is not what you have, is it? I have found the Keihin headers to be extremely high quality and not the "non OEM almost fits" category of part. Something is definitely wrong here. If you have no dealer recourse, a good muffler shop should be able to resize them. I assume in addition to anti-sieze on the threads that you are also using it on the header stubs?

  14. #14
    . AntonLargiader's Avatar
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    Is this on a G/S where you have a 36mm pipe but a 38mm exhaust port?
    Anton Largiader 72724
    largiader.com bmwra.org

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    Cool

    Quote Originally Posted by AntonLargiader View Post
    Is this on a G/S where you have a 36mm pipe but a 38mm exhaust port?
    Hi Anton: This is just a naked R80.

    ISSUE RESOLVED: I started measuring all specs of pipes, inlets, et al.. All seemed appropriate and the O.D. of the Keihan headers is 38mm. I emailed Keihan in England and let me just say they were great. Got almost immediate reply and they were more than
    helpful. I sent back the stamped part numbers for my headers and although one was off by a digit (just a typo it seems) the headers were the correct fitment for my '86 R80.

    Well, moving ahead to this morning, I went to take our City recycling out and there in the recycling bin were my old compression rings from the old 2-into-1 system. I immediately grabbed them up and compared them to the new compression rings I just purchased. BAM. There is the issue. The old rings were about the same size as the clamp ring. The new compression ring is about 3 times the size of the old rings - same diameter just larger in width of the ring depth, if you will. That accounts for the not being able to hand-wrench the finned nuts down against the jugs.
    Sooooo, I took the new clamp rings which are the same size as the "new" clamp rings I just purchased and used the "old" compression rings.

    The headers tightened up nicely on both jugs and screwed-down by hand using all the threads. PROBLEM SOLVED.

    I'm not going to rent more space in my mind to trying to figure the what-fors and why-nots on the larger compression rings. Time to move on.
    The "old" compression rings were like new and I cleaned them up and they are in nicely. I'll install the remainder of the system this evening when the temps. drop down a bit here in Central Florida.

    BTW, I can't say enough good things about the Keihan exhaust system or the super response from the Keihan factory personnel. Highly recommend their systems if you need a replacement.

    Thanks to all for their input. This was driving me crazy and now time for a cold toast to the Forum members and one for me, too. Cheers.

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