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Help Inline 4 slip on exhaust upgrade & FZR250 EXUP valve rattle repair

Discussion in 'Yamaha 250cc In-Line 4's' started by Brandon Otte, Oct 15, 2020.

  1. Brandon Otte

    Brandon Otte Well-Known Member

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    Hi everyone,

    I’ve been looking for an aftermarket slip on exhaust for my fzr250. I’ve come across many various makes and designs online ranging from dirt cheap to very pricey. I’d like the cheapest, easiest option. Biggest question really is the sizing and whether they will fit/slip on.
    Does anyone recommend any specific items for the little Yamaha with any experience. I did try remove the muffler which was deafening and illegal. I have thought about gutting my standard muffler but obviously it’s not reversible so if I muck it up.... perhaps buying a spare and gutting that one?

    And also has anyone had any experience repairing the EXUP valve - the annoying rattle at idle that is, works mint still.
     
  2. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    There's a link half way down the page here for EXUP Maintainence
    https://2fiftycc.com/index.php?thre...-powervalve-information-and-maintenance.1099/

    The standard muffler was originally welded to the exhaust after the exup
    With the new muffler just measure the exhaust pipe where you want to slip the muffler over and buy that size muffler in the style you like.
    If the muffler you buy is a little tight to get over the pipe take it down to your local exhaust shop and have them flare the pipe just enough to be a slip on fit
    Some use 2x spring's and a couple of hook's that are welded to your pipe then you fit the spring onto the hook's to hold the muffler there, and some muffler's are simply clamp on

    @Linkin bought one of the JRE ? muffler's for one of his FZR's, also think another member used the same one more recently
    https://www.ebay.com.au/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313&_nkw=jre+muffler&_sacat=0

    This might still be available too ?
    https://2fiftycc.com/index.php?threads/musarri-50mm-universal-slip-on-muffler.11064/
     
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  3. gregt

    gregt Well-Known Member Premium Member

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    I've repaired a couple of 400 EXUP valves. In both cases it was the bearing at the inner end - the small one - which had worn.
    I drilled the hole in the cast exhaust piece bigger and made a bush to suit. The holes wear out of round so drilling larger gets you back to a round hole.
    The bush has to be heat resistant and wear resistant. I used cast iron. An old (british) valve guide from the scrap box.
     
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  4. Brandon Otte

    Brandon Otte Well-Known Member

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    So was that worn bearing causing your valve to rattle like a tin can at idle?
     
  5. Brandon Otte

    Brandon Otte Well-Known Member

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    @my67xr my muffler is standard and is slip on. I’ve found a LeoVince slip on muffler which I’ll pick up this afternoon. Im hoping it’ll fit, just winging it.

    30A43440-1249-4BA5-ACD1-3CBB6C88B4C7.jpeg
     
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  6. gregt

    gregt Well-Known Member Premium Member

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    Customer bikes. Heard them coming so simply said, I can fix that, you pull the pipe off and bring it in. Saved them money - and me time. Yes, it works. The inner bearing is a blind hole in the casting. Condensation, corrosion, heat and acidic gases all combine to give it a hard life. It's a steel pin in what i think is a nodular iron casting so very basic metallurgy.
    Anything better would be many times the price.
     
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  7. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Been a long time since I've had it apart, however when I looked into the EXUP for the rattle source and the bearing came out easily and was bronze - always meant to get a replacement but never got around to it
     
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  8. gregt

    gregt Well-Known Member Premium Member

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    Ouch. Bronze is not a good choice for a bearing there. Sure it was OE ?
    The ones I've dealt with - 400's and a couple of 1000's - were all direct into the casting, no separate bush.
    I haven't looked at a parts fische for the 250's so I may be totally wrong there.
     
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  9. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    The exup collar on my spare exhaust is either bronze or non magnetic stainless
    The collar seem's to be retained on the shaft, possibly from corrosion on the cast iron valve ?
    Bush inside the exhaust i'd need to clean up to see what it's made of


    20201017_142512(0).jpg 20201017_142540.jpg

    90387-106U7 Collar
    [​IMG]

    No real life picture's of the bush though, part's 11 and 15 below

    [​IMG]
     
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    Last edited: Oct 17, 2020
  10. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Ok, after a quick vapour blast and a test with a magnetic pick up tool the bush is also non magnetic,
    infact the whole exup housing on the exhaust is non magnetic so i'm guessing stainless for the housing

    20201017_145749.jpg
     
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  11. Brandon Otte

    Brandon Otte Well-Known Member

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    A9F6A435-22AA-4E81-B25F-337205B4CC81.jpeg @my67xr that cleaned up well with a blast! So I’m gathering I’ll need to replace the bush and collar? Parts 11 & 15... or as @gregt mentioned to drill out the housing hole and fit an oversized collar to suit?
    I would think(without prior knowledge or ever looking at my EXUP valve) I could replace both parts 11 & 15 without any machining - not that I would know...
    I fitted my LeoVince muffler last night after some slight modification. Went for a quick spin around the block and wow it sounds amazing!!! Pops and flames out the rear too :) I regret not wearing ear plugs as my ears were still ringing this morning. Went for another ride this arvo, with ear plugs, and sound track wise it makes a world of difference, not sure if it’s just the sound making me “feel” more power?

    I always tried wearing ear plugs to muffle the wind noise through my helmet but then I couldn’t hear the exhaust note. Now I can have plugs in and enjoy the pure inline 4 screamer soundtrack. I hope it doesn’t attract attention from bystanders though.
     
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  12. Brandon Otte

    Brandon Otte Well-Known Member

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    @gregt I see you’re in NZ as well. Do you still work on exhausts, if so would you be willing to repair my EXUP valve for your fee if I could arrange postage? Providing I can’t do it myself.
     
  13. gregt

    gregt Well-Known Member Premium Member

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    I'm in the South Island. I'd look for a small general engineering co local to you.
    Looking at the pics, I'd think the separate bush is a distance piece which limits endfloat. I suspect the plain pin on the end is actually the bearing surface.
    Material is probably Inconel. A high temp stainless alloy.
     
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  14. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    From memory, the rust pitting on the EXUP valve itself is the problem, making it loose and rattle
    if inconel is available in a thin wall tube which could go over as a sleeve then drill the bearing to suit

    I don't see much point replacing the bush and bearing when it's the pin on the end of the EXUP valve which is the problem
     
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  15. Brandon Otte

    Brandon Otte Well-Known Member

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    Hi again,

    So since that first night with the new muffler I can't help but feel as though it's down on power. I mean I'm not sure if the first night was cold and just the sound alone made it feel quicker or at least the same as with the stock muffler. It's definitely alot warmer here over the last few weeks.
    Would I be wrong in thinking with this muffler its allowing the exhaust to flow free and maybe running lean?
     
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  16. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    From everything that I've read, as I've only ever bought bikes with aftermarket pipes on there already, you've maybe got higher exhaust flow at high RPM - requiring larger main jets

    How much larger? - Good question
    To take the guesswork out of it, you could do a plug chop in 2nd or 3rd gear to at least get some indication of where it's at
     
  17. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    IMHO I seriously doubt that it needs 'big jets'. If it was flowing more air then it would also flow more fuel.
     
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  18. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    You reckon they're tuned and jetted a wee bit rich already, which I think is very likely correct.

    Pondering what would give the impression it's down on power - would a slightly louder exhaust which makes it sound like it's going harder than it really is give that impression?

    The EXUP doesn't get completely out of the way until ~10K RPM or thereabout does it?
     
  19. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    To be honest... a simple muffler change would make SFA difference if nothing else changes. I would hazard a guess that the Inlet side is the limiting factor with regard to fuelling...
     
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  20. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    How clean is your air filter ?

    When i fitted a bigger muffler onto my XT250 i needed to go down 1 jet size on the main as it was making the spark plug dark brown at 100km/h, and would sometime's sputter and cut out
     
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