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1981 XJ550 Seca Custom Airbox/Boots Replacement

Discussion in 'XJ Modifications' started by TerenceKibley, Sep 9, 2018.

  1. TerenceKibley

    TerenceKibley New Member

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    Afternoon gents,

    WALL OF TEXT AHEAD sorry

    Just wanted to ask for some opinions from the more experienced members in the forum.

    I own an '81 XJ550 Seca that I'm fixing up to be a cafe racer/scrambler. Now before everyone stones me to death, yes I've read up on the whole pods thing on the forums (for the last two months or so) and as far as I know the consensus is still "use the stock airbox", which I was planning to do however I noticed that the carb-to-airbox boots are worn out, beginning to tear and don't quite fit (no amount of immersion in boiling water or heating with a hairdryer could get the two ends to fit).

    I would like to get stock replacement boots however I can't seem to find anywhere near me (I'm in Canberra, Australia) for a decent price. I've searched eBay, Gumtree and the nearby wreckers but no luck acquiring a pair for a decent price (an airbox is like $300 AUD + shipping from the US on eBay and Chacal is in America).

    So my idea is to measure out the volume of the original airbox plus the length and diameter of the velocity stacks and remake them out of some other material. I was thinking PVC (cheap but might melt due to heat/petrol) or aluminium pipe (expensive) for the intakes with the same length and diameter of the original boots, with smooth lathed out surfaces all going into a plenum chamber. The airbox could either be one box with a gigantic pod filter, a box with 4 pod filters for that sweet, sweet cafe racer look, or a bread-box style filter (one end is mesh and the inside is filled with filter material). I'm thinking he box will likely be longer and flatter than the original and be screwed to the bottom of the seat. I just wanted to find out if anyone has done something like this and can tell me about their experiences or has any ideas regarding the physics of the problem.

    The cafe racer plan is a fairly long term one. I am planning on TIG welding up some new pipes/mufflers, sourcing a new front end, rewiring, remaking the seat etc. I want to keep the bike at least rideable and on par with stock performance but I'm a realist. My philosophy is that if I wanted cutting edge performance I would just hop onto my '97 CBR600F3 and ride that instead so this is a project for the love and the art of it and the experience of building a bike with my own skill and two hands.

    Sorry for the wall of text, I just wanted to fend off the inevitable "pod filters are terrible", "stock is best" arguments that plague this forum. I want to come up with a novel solution to the problem for the fun of it and want to just gauge if the project is within my capabilities.
     
  2. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    PVC and CPVC have both been used before, and both will melt.
    SIlicone radiator hose has been used with a fair amount of success.
    There are a few threads about homemade airboxes that might be of interest to you.
    custom airbox site:xjbikes.com

    Airbox volume is only one factor to consider. The shape of the airbox will effect intake charge distribution as the intake pulses move through the airbox. That's not a critical factor, but playing around with that may be entertaining and yield some modest performance enhancements.
     
  3. a100man

    a100man Well-Known Member

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    I used some silicone hose to replace the 'stubs' from the airbox to he carbs on my FZ750. I cut back the original hard airbox rubbers, the silicne then slipped over the remaining stubs and the carb mouths.
     
  4. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    Interesting-- can you do a write-up?
     
  5. Polock

    Polock Well-Known Member

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    i thought someone found a "Fernco fitting" that worked
     
  6. TerenceKibley

    TerenceKibley New Member

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    Seconding hogfiddles above, do you have any pictures or a write up? I'm having a hard time visualising it.

    Polock, do you have the thread for that? I'm having a bitch of a time finding OEM replacements anywhere near me and I'd rather not ruin my bike's performance
     
  7. Polock

    Polock Well-Known Member

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    no link, that was a long time ago. make some cardboard cutouts of the sizes for both ends and go see the guy at the plumbing store.
    the airbox side would be the tricky size because plumbers don't use the outside of those fittings
    let us know if you find something
     
  8. a100man

    a100man Well-Known Member

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