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XJ550 4-1 PROS & CONS

Discussion in 'XJ Technical Chat' started by Noahsxj, Nov 28, 2021.

  1. Noahsxj

    Noahsxj Active Member

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    01236E35-6C3A-452A-9BA3-BB413DDFAF9D.jpeg E7FE3046-88D6-4351-A126-3F91931207AF.jpeg 66E77F75-CB92-42D8-9D62-2EFC513F33F4.jpeg 5A2B5FBA-EB57-47F1-BD32-93CDE5A9E7DC.jpeg Hey guys, hit a pretty good jackpot on todays junkyard visit

    got a 4-1 header assembly for my xj550 that I’m conflicted about

    also picked up a really nice sissy bar and battery mount for my virago, and a xj550 igniter unit.

    (the yard I go to has TONS of xjs, viragos, xs’s, so if you need parts, lmk and I’ll see what I can do)

    anywho, the 4-1 as you can see has some dings and dents. I’m sure I can get all the rust off pretty easily as it’s all surface.

    but, I’m wondering if I want to use it or not.. I may be willing to sell it to someone who really wants 4-1, but I’m wondering what some pros/cons are?

    I’m jetted a bit rich as is, I am high altitude(6000 feet)

    and running 2.5 sizes larger on the main jet for a stock airbox and Harley sportster mufflers

    so, I’m confident with these jets I can swap exhausts without rejetting, but I’ll have to find a suitable muffler, that sounds good enough to make this swap worth it, but not too obnoxious or re-tunable.

    What are the main differences in sound and performance?
     
  2. Minimutly

    Minimutly Well-Known Member

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    4 into 1 sounds really nice. You should pick up some top end power, but likely lose some mid range. The difference might not be noticable, but the sound will be :)
     
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  3. Noahsxj

    Noahsxj Active Member

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    Thank you!
    I do like the sound a lot better from what I’ve heard on videos(not ever good quality of course)

    but I’ll be honest, my riding habits tend to lean more in the low end/mid range rpm range.

    so this is more of an aesthetic or race modification if you had to categorize it?
     
  4. Jetfixer

    Jetfixer Well-Known Member

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    For some reason some systems interfere with removing the stock oil filter ,maybe not if you have the spin on oil filter conversion . Good score though.
     
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  5. Noahsxj

    Noahsxj Active Member

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    I really want to do that, I suppose now would be a good time! I just finished adding an oil cooler with adapter plate from an fj600, the 4-1 doesn’t look like it will interfere with any of that, but a spin on filter would be a rad addition

    i also need to address an oil pan leak I’ve been putting off because of the oem 4-2.

    would you or anyone else on here happen to know the OD of the 4-1 muffler port? I want to start looking into mufflers
     
  6. dkavanagh

    dkavanagh Well-Known Member Premium Member

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    I have period Kerker 4-1 and that header reminds me of the one on my bike. I still have the regular filter and center stand, so if this one fits without altering these things, it may be a Kerker header.
     
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  7. Noahsxj

    Noahsxj Active Member

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    That would be cool, the bike it came off of looked like it had been in that same spot for longer then I can imagine, probably since the 4-1’s where readily available.
     
  8. Jetfixer

    Jetfixer Well-Known Member

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    The spin on oil filter is a great item , I have it on both of my 82 750 Seca's , Xj4ever sells these paid 100$ well worth it .
     
  9. Minimutly

    Minimutly Well-Known Member

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    $100 each?
    How is this good value? Does it stop you making a mess? Are the filters a lot cheaper? Maybe it's just more idiot proof?
     
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  10. Noahsxj

    Noahsxj Active Member

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    100 is a bit steep, but I think it’s just slightly more convenient

    and looks cooler for sure haha, if you get a cool oil filter
     
  11. dkavanagh

    dkavanagh Well-Known Member Premium Member

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    personally, I like the stout, standard oil filter housing. It is more parts to fuss with though.
     
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  12. Jetfixer

    Jetfixer Well-Known Member

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    Both of my Secas had the filter bolt rounded off and were siezed by PO , replaced bolt and the housing dripped even though I had put new O ring , I have also had trouble finding the stock oil filter locally . The spin on oil filter is to me worth it and if I wanted to easily removed and stock filter can be reinstalled.
     
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  13. dkavanagh

    dkavanagh Well-Known Member Premium Member

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    @Noahsxj just to be clear, the kit to convert is $100. Filters are as cheap as you'd expect for spin-ons... like 5-10 bucks depending.
     
  14. Noahsxj

    Noahsxj Active Member

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    @dkavanagh right, I was just saying that if someone does this mod strictly for aesthetic reasons, wouldn’t it only be worth it if they used aesthetically pleasing filters? Like K&N, chrome, color matched, etc

    If you’re going to be using cheap generic spin ons, then yeah I’d prefer the looks of the oem filter housing

    As for me, I already have a pretty cosmetically modified xj550, along with the oil cooler, so I have considered it for looks.
    Now if the 4-1 causes fitment issues, it would be for looks, and functionality.
     
  15. 50gary

    50gary Active Member

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    If the 4 into 1 makes that same power as the stock system, it will make your bike faster. The weight reduction is worth 1.5hp in
    power to weight ratio before and after the swap. Im listed stock weight ('82 750 Maxim) is 524# at a rated 82 bhp p/w is 6.39# per hp
    1.5 x 6.39 = 9.5#. I'm quite sure I saved at least that amount from stock exhaust to my 4/1 system.
    edit; I just checked my 4/1 weight and it's 18.75# made of fairly heavy guage (16ga mild steel)
    Cheers, 50gary
     
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  16. Noahsxj

    Noahsxj Active Member

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    found a muffler that may work?
    Or it might be too straight..
    65DE83A0-A43E-4CF1-A650-47835630DBD0.jpeg DFE4ABA0-DBC6-47C7-801E-7EB2AE4042C9.jpeg F95CD169-455F-42BB-9DF1-32B6141EF484.jpeg 564F34D5-4FAE-4671-BD48-B7599E02F149.jpeg 2B392825-E2E7-42EF-B06A-297A2C318B22.jpeg
     
  17. dkavanagh

    dkavanagh Well-Known Member Premium Member

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    Here's how my kerker 4-1 fits on my bike. This picture is several years ago before I made some of the engine covers pretty and got a better looking Kerker muffler.
    Screen Shot 2021-12-09 at 7.29.50 PM.jpg
     
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  18. Noahsxj

    Noahsxj Active Member

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    @dkavanagh that definitely looks like the one I’ve got, similar welds, shaped collector, pipes.

    probably is a kerker!

    What would you say the diameter of the baffle is on the muffler?

    this muffler looks to have a pretty complex baffle, which is kinda why I chose it.

    But I wouldn’t mind checking out some others too.

    id like to not have to rejet again
     
  19. Noahsxj

    Noahsxj Active Member

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