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4 into 1 v. 4 into 2

Discussion in 'XJ Technical Chat' started by motorduck, Apr 12, 2009.

  1. motorduck

    motorduck Member

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    Quick stupid question:

    What is the difference between 4 into 1 exhaust and 4 into 2 exhaust?
    Is it mainly an aesthetic difference?
    Does one perform better than the other?

    Please excuse my ignorance.
     
  2. protomillenium

    protomillenium Member

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    4>1 improves efficiency 2 ways:
    #1, you lose the weight of one muffler.
    #2 because the 4 pipes come together into a collector, one exhaust wave will draw the exhaust from the next cylinder.
    4>2 sounds better, looks better and is more quiet.
    However, build and designs vary in quality.
     
  3. MN-Maxims

    MN-Maxims St. Paul Minnesota

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    The last XJ1100 I have been working on has an 4 into 1. I don't like it since when you go to drain the oil, it is hard to get at the drain plug and the oil runs over the collector. You start it up and it burns that oil off. The other problem is that to get the rear tire off you have to remove the whole exhaut system to get at the axel bolt. This is a MAC system. The last thing is there is a rattle in the baffle and I need to pull it out to repair or replace. Its in there pretty good. My vote is to get the 4 into 2. More room underneath and would seem to be more serviceable.
     
  4. johno8

    johno8 Member

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    I have a Mac 4-2 system and the folks I got it from on eBay said there were no Mac systems for my XJ750, but the XJ700 one worked perfectly. Not sure about your ride, but the 4-2 is everything that protomillenium says.
     
  5. motorduck

    motorduck Member

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    Yeah. I think I'm going to stick with the 4-2 system. Thank you so much for your advice/input. I don't need that much increased performance and I DO need simplified serviceability.
     
  6. greggvickrey

    greggvickrey Member

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    Motorduck, I have an 81 XJ650 with a 4-1 Mac exhaust system that I put on to replace the stock 4-2, it was rusted out bad. I do not have a problem accessing either the oil filter bolt or the oil drain bolt on mine. As far as performance & sound I can't compare to stock, as mine wasn't running before I switched exhaust systems. All I can say is I am pleased with the sound it has, the look and the performance. I also have no problem accessing/removing the rear wheel with it in place. Which ever you choose I'm sure you will enjoy it when you are done. I am running the stock air filter/box with this setup & did not have to rejet.
    Gregg
     
  7. SQLGuy

    SQLGuy Well-Known Member

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    I've got the Mac 4-1 on my 750 Seca. I bought it to replace the stock 4-2 system when a guy with a 5th wheel ran it over in a parking lot (originals mufflers being hard to find and pay for).

    I can say it's definitely louder and sounds a bit weird at low RPM's. At high RPM's it sounds much more sport bikeish than the stock exhaust. I had no trouble getting to the oil drain plug or filter housing, though the oil does drain onto the exhaust (cleaned it off with a bit of brake cleaner before starting). The exhaust does not block the rear wheel in any way... basically connects up just like the stock right-side pipe.

    I have heard reports about these systems not sealing well and leaking either at the exhaust ports or at the collector. Mine's tight throughout, and I have no complaints in this regard.

    As for performance, I'm not particularly convinced at this point. I think I need another dyno session before I can say for sure. It definitely is a lot lighter, though. The stock system, especially the collector box, has a decent amount of metal in it.
     
  8. Awalker19

    Awalker19 Member

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    Does anyone have a 4-4 system? I was thinking about building just straight pipes. 2 on each side dumping at the axle.
     
  9. WesleyJN1975

    WesleyJN1975 Member

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    How cool would it be to look like this 4-4 on both sides?
     
  10. MN-Maxims

    MN-Maxims St. Paul Minnesota

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    Saw a Honda 550 today with 4 mufflers. It looked like it was in nice shape. I know how spendy two stock mufflers can get. Bet 4 is unobtainium.
     
  11. dpawl31

    dpawl31 Member

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    4>4 would look like a VMAX O_O

    I have a 4>1 on the non-running SECA.
    Don't know the brand, and the headers are rust.
    But easy access to the oil bolt...

    Sounds amazing... from what I remember!

    It seems to be as old as the bike...

    Wonder if I could pull it, get it professionally cleaned and sell it, or even try it on the maxim...?
     
  12. RangerG

    RangerG Member

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    I have a Yoshimura 4-1 on my 550. It's louder. I can access the oil drain bolt fine but the oil filter cover will not slip out between the pipes. I have to tilt the cover and just pull the oil filter out. I have to make a cardboard funnel to keep the draining oil off the pipes. Last but not least, I no longer have a center stand. It won't fit with the 4-1. Not a real big deal for your shaft drive but in order to lube the chain I end up pushing the bike a half a block it seems.
     

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