2 to 1 exhaust

Discussion in 'Airheads' started by Sabre170, Feb 18, 2013.

  1. Sabre170

    Sabre170 Been here awhile

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    I have a '78 100/7 that I'd like to convert my exhaust to a 2-1.

    Sadly, I don't have the ability to manipulate metal to make my own pipes. I'm fully aware of the MAC pre fab'd 2-1 exhaust, but have had no luck finding any other pre-fab'd ones.

    Does anyone have any other suggestions?
    #1
  2. 100RT

    100RT Been here awhile

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    I'm curious as to why you want to go that route. I wish I could convert my 1150RT to dual exhaust so it sounds like a motorcycle. My 81 R100RT sounds much better.
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  3. Sabre170

    Sabre170 Been here awhile

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    Well, it is kinda a 2 fold answer, but honestly, mostly cosmetic. I converting the /7 to have more of a cafe look/feel to it. As part of that, I'm trying to "clean up" the bike as much as possible. (I.e. I removed fender, turn signals, ect). I figured that going for a 2-1 would help with that.

    A secondary goal of the 2-1 was I was hopping to get a bit more aggressive/throaty sound out of it. The current exhaust/muffler is pretty good at doing its job at muffling the sound.

    However, from what you are saying, a 2-1 will be counter productive to my secondary goal. Maybe a 2-1 header isn't my solution, rather keep my current header but put on a cleaner looking (smaller?) set of mufflers on that will also give the resulted sound???

    Thoughts?
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  4. 100RT

    100RT Been here awhile

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  5. 100RT

    100RT Been here awhile

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  6. Sabre170

    Sabre170 Been here awhile

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    Thanks! I really appreciate.

    I really like the looks and sound of the exhaust in the second link you posted. The R100 with the "shorty" megaphones. I, thinking that will likely be exactly what I'm looking for.

    Do you know off hand what size header pipes my '78 100/7 would have on it? I'm out of town for the next week and can't measure my bike. I want to say that the muffler would need to fit a 38mm manifold pipe, but 40mm and 42mm are also rattling around in my brain as possibilities.
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  7. supershaft

    supershaft because I can

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    Sound like a motorcycle? Two into one has nothing to do with that. I have heard many a two into one system on airhead race bikes and street bikes that sounded awsome. A couple of the race bikes ran like mofo's. You want noise? A friend of mine had a Luftmeister two into one and took the baffle out. He rightly called it his Horn of Jericho. The Horn from Hell would have worked too! :D

    One muffler is lighter than two. Typically speaking two into ones help low rpm perfromance at the expense of top end performance. Two into two's just the opposite. With one or two crossovers, most of our two into two setups are half way there to a two into one anyway. Crossovers on two into two's do make them quite a bit quieter. Each cylinder gets to use both mufflers at the same time which would make many of our two into two's quieter than a comparative two into one. Performance? Noise reduction is the main reason behind our crossovers under the tranny.
    #7
  8. 100RT

    100RT Been here awhile

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    Supershaft, I guess your not familiar with the 1150RT exhaust system sound. Or should I say lack of sound.
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  9. supershaft

    supershaft because I can

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    I am very familar with the sound. Their sound is for their muffler and cat. The volume and even the tone to a large degree has almost nothing to do with the fact that it's a two into one system. I have welded up from scratch a number of two into one exhausts for an oilhead racebike that I use to work on. It made some noise. It made good power too. I think we had more power than anyone that year from being at the races and reading a years later tuner's interview in Cycle News. We just didn't have the handling or the rider. Our rider was good but he was up against quite a few old and some not so old hired hands. Plus, another four time AMA 250 GP race winner rode the bike and said it handled like a death trap. Something that I could tell all along but . . . . When Matt Mladin retired he said in another Cycle News interview that one of the riders we were racing against was one of the best riders he had ever raced with.
    #9
  10. Airhead Wrangler

    Airhead Wrangler Adios Mexico

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    The oilheads are quiet because you could fit most of the contents of a 55 gallon drum inside the exhaust system. Huge amounts of volume in there (liters, not dB). The more volume (liters) the less volume (dB). Add effective baffling on top of that and that's why your fuel pump is louder than your exhaust.
    #10
  11. isdt BMW

    isdt BMW willserv@aol.com

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    38mm is very close to 1-1/2" standard /5 thru/7 pipes are 38mm
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  12. Airhead Wrangler

    Airhead Wrangler Adios Mexico

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    Make that all /5 and later airheads with the exception of some '77 RSs.
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  13. Boxer Metal

    Boxer Metal Mad Scientist

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  14. dave0

    dave0 Adventurer

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  15. bone13

    bone13 Been here awhile

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    While no longer available these occasionally pop up used (and I never seem to have available cash when they do)
    Supertrapp made a sweet 2 into 1 (used to have one and I would LOVE to find another one someday)
    and Luftmeister made a pretty good 2 into 1, years ago.

    I just lucked into one of the luftmeister's (which I need to go pick up) recently that I intend on using for a cafe project.
    #15
  16. motu

    motu Loose Pre Unit

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    I made my own equal length 2 into 1, and use an IDS2 Supertrapp on it. I think a 2 into 2 with short mega's sounds better, but they are too loud. The Supertrapp is loud (race core), and number of discs makes no real difference to db with a race core, I have trouble keeping it under 100db which is our limit....usually get it on 97db for the test. The noise is harsh and almost buzzy at high rpm, but performance is better all round than the stock set up - I've played around with the Supertrapp a fair bit, currently running 10 discs and 2'' end cap...with 6 discs and 38mm end cap it's pretty close to stock....but louder.
    #16
  17. Houseoffubar

    Houseoffubar fine beer sampler

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    38mm or 1 1/2"
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  18. supershaft

    supershaft because I can

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    Unless your rev range is around 1500rpm or less, all pipes without variable volume via valves and plenums and whatnot, no matter the type, are going to rob power. The question is where in the rev range and how much. That is simply a fact of physics.
    #18
  19. Boxer Metal

    Boxer Metal Mad Scientist

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    I've built 2/1's that made power from 1800 RPM to through red line. It is very do-able and yes it is all math from pipe length, collector length and diameter.......
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  20. Airhead Wrangler

    Airhead Wrangler Adios Mexico

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