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Rebuilding the Yamaha Vacuum Fuel Valve w/pics

Discussion in 'XJ DIY How-To Instructions' started by bigfitz52, May 9, 2010.

  1. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    Even rebuilt, they do need to be periodically cleaned; remember it's upstream from any inline fuel filter and subject to catching crud big time.

    Don't assume failure; it's amazing how many things can be fixed with a good disassemble and clean.
     
  2. crow

    crow Member

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    Strewth bigfitz that's some beautiful work.
     
  3. heelflip131313

    heelflip131313 Member

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    You're the best
     
  4. Jamie

    Jamie Member

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    I couldn't agree more. This is one of "the" best documented DIY tips that's on this site. You do some nice work my friend!
     
  5. Xjmike

    Xjmike Member

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    it's amazing how he does it. IT looks like it's brand NEW!!!!!! like it came straight out of the factory. Free from wear and defects.
     
  6. Robert

    Robert Active Member

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    Hey Fitz, on that second seat that was too pitted to polish out... I had a similar issue with a 650 petcock. I used a 60 degree counter sink to "kiss" the face of the bevel and after 0.004", it was pretty as new. I need to get the rebuild kit in so I can report on how well this worked so more news later. I'm ordering the delux OEM rebuild kit with the aftermarket spring to compensate for the removed material. What say you?
     
  7. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    I saw that in your other post, and thought "brave SOB anyway."

    I'd be worried about removing too much material. As long as the "head" of the diaphragm assembly is still long enough to reach in there and seat the o-ring properly, without bottoming out on the spacer plate, it should work. I'd definitely use the longer aftermarket spring; you may or may not need the "booster" washer as well.

    Sounds like you used a "machinist's touch" and are probably ok.

    I've got one right now that has a couple of stubborn wear rings in it; I'm just going to step up to valve lapping compound and give it a quick whirl, then re-polish.
     
  8. adrian1

    adrian1 Active Member

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  9. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    Lots of good stuff in that article; unfortunately he's dead wrong on a couple of key points; I'm not going to pick it apart but if you carefully polish the valve seat so that it's shiny new smooth (under a magnifying glass) the rebuild kits work fine if you use their slightly longer/stronger spring.

    The key is the valve seat; but a good careful polishing will do the trick.
     
  10. i_am_the_koi

    i_am_the_koi Member

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    Any reason i couldn't bead blast this instead of cleaning it by hand?
     
  11. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    Depending on the pressure and coarseness of the beads you use, you run the risk of pitting the metal, especially in that o-ring seat area. The metal used in these petcocks is kind of "soft" and if you put gouges in any of the sealing surfaces, the petcock body is toast.
     
  12. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    I'll go a bit stronger than that: NOOO!!!! Bead blasting will simply ruin all the parts.

    Soda blasting only; and don't concentrate the blast on the valve seat area for any length of time.

    The metal in these petcocks is soft enough you can scratch it by biting it. Honest. Kinda like gold...
     
  13. Alive

    Alive Active Member

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    This thread is the stuff legends are made of :)

    Love your work.. Especially Len and Fitz in this case ;)
     
  14. i_am_the_koi

    i_am_the_koi Member

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    K, just bought a cheap gun and have loved what it's done so far for parts of the GS450.... Curious as to what else I can do... My motorcycle trailer's next
     
  15. silverdollar

    silverdollar Member

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    This is what I been looking for, thanks
     
  16. silverdollar

    silverdollar Member

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    where can I buy the on/off replacement value?
     
  17. silverdollar

    silverdollar Member

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    where can I buy the on/off replacement value?
     
  18. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    XJ4Ever; click the logo in the site banner or PM member chacal.
     
  19. Hedley

    Hedley New Member

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    Back on the road thanks to your tips!
     
  20. kontiki

    kontiki Member

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    Finally got my petcock rebuilt. Thanks Fitz.

    I didn't purchase a new filter pipe because mine was in great shape. I did notice what appeared to be some sort of epoxy residue when I removed it and had to pick it out and clean around the flange where it was seated. I'm wondering if I should apply a bit of epoxy around the base of the filer to insure a good seal before I put it back on? It fits relatively snug in the petcock body but I doubt it is fluid tight.
     

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