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79 Special II Resto Cafemod "Doomy"

Discussion in 'The Garage' started by Machine, Nov 22, 2019.

  1. Mailman

    Mailman Hardly a Guru Top Contributor

    Dang Randy! You’ve been busy! I must’ve nodded off for a while, I missed a bunch. :D
    You sure do nice work buddy. ;)
     
    Machine and Jim like this.
  2. Machine

    Machine Race the wind Top Contributor

    :umm: eeks. Well I have one other set of #135 main jets and 27.5 pilot jets. I'm pretty sure they pin check size the same but I'll look tomorrow. If I've over jetted that much , I'll just saw off the mufflers and run straight pipes :lmao:
    I could not find a reliable jet hole size chart... It is really cool how easy it is to drop the float bowls and change jets on BS38's :thumbsup:
     
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  3. Machine

    Machine Race the wind Top Contributor

    Thanks Bob ! Yes, I am going to let some creativity flow. This 79 is catching my interest more and more. My best shocks and double disc brake parts and such are migrating on their own towards the 79 Cafe in the nights. Looking forward to all that happens myself even..
    -R
     
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  4. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Well, maybe a rethink here.
    Most of my experience was with Honda Keihin jets, which conform to that sizing scheme. Here's a chart compiled by another member, showing the Mikuni jet numbers being smaller...

    JetSizes.jpg
     
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  5. Machine

    Machine Race the wind Top Contributor

    Mikuni #135 on that chart shows .061 ?
    Not what I find. More parts out first thing for
    lo_Oo_Oking closely

    20191127_060458.jpg
     
  6. Machine

    Machine Race the wind Top Contributor

    20191127_073320.jpg Virgin 78/79 Mikuni original jets Have to clock in for awhile,
    Thanks everybody o_O
    -RT
     

    Attached Files:

    Last edited: Nov 27, 2019
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  7. Machine

    Machine Race the wind Top Contributor

    I crept up on those #27.5 Mikuni pilot jets hole size from loose .018 then Smooth .019 pin.
    o_Oo_O figuring out some closer bore inspection to match TwoMany's great pics !
    :yikes:
     
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  8. Machine

    Machine Race the wind Top Contributor

    20191127_075255.jpg
    Bingo ! pics :smoke:
     

    Attached Files:

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  9. Machine

    Machine Race the wind Top Contributor

    20191127_082753.jpg
    Stashing these carefully selected carb items here for this 79 BS38 set. Score :D
    Still on track but the set must go home for cleaning/assembly
    -R
    Check out the as found bowl condition I pulled the jets, mixture screws, etc out of..
    -R
     

    Attached Files:

    Last edited: Nov 27, 2019
  10. Mailman

    Mailman Hardly a Guru Top Contributor

    You’ve got some pretty neat measuring tools at your disposal Randy! :thumbsup:
     
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  11. Machine

    Machine Race the wind Top Contributor

    20191127_063730.jpg
    Ironically I manufacture to fit very very tight tolerance (.0001's) bores everyday lol :lmao:
     

    Attached Files:

    Last edited: Nov 27, 2019
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  12. Jim

    Jim Beyond the edge, is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Me neither. Here's a new Mikuni #135. I don't have your fancy standards Randy, all I got is a set of tip cleaners. A .048" is a loose fit and a .055" won't fit. I've checked that caliper against my mic. standards and it's within a thou. across it's range.

    IMG_20191127_111010.jpg
     
  13. Machine

    Machine Race the wind Top Contributor

    The .055 small orifice file is not "straight enough" to fit Jim. That and my pins set is new..
    ;)
     
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  14. Jim

    Jim Beyond the edge, is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Thinking the tip cleaner might be deformed from use, so I tried some drill bits. A #54 bit is a perfect fit on the #135 jet. Measured 2 jets and they both agree.


    IMG_20191127_113746.jpg
     
  15. Brassneck

    Brassneck XS650 Guru

    Really enjoying this thread, and looking forward to seeing how it will all come together. :)
     
    MaxPete, Raymondo, Mailman and 3 others like this.
  16. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Looks like a "reliable jet hole size chart" needs to be acquired, or built.

    One of 5twins' pics of the later VM22/210 76-79 pilot jets shows that the metering orifice is at the top of the jet, rather than the bottom of the other BS30/96 pilot jets.

    XS650CarbSpecs02.jpg
     
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  17. Machine

    Machine Race the wind Top Contributor

    Perfect sense on #54 (.055)
    The main jets are big and meaty to uphold original size.
    The Pilots shape inside and size tolerance is much more critical ?
    Assuming ..
     

    Attached Files:

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  18. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    For me, much of this jet sizing was a bit of a black mystery. For example, in the early '70s, we encountered VM series mainjets that were marked double their expected size, like #280 mains that had the same orifice as normal #140 jets. Figured that it was maybe a way to ensure that VM jets stayed with VM bodies...
     
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  19. Machine

    Machine Race the wind Top Contributor

     
    Last edited: Nov 30, 2019
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  20. Machine

    Machine Race the wind Top Contributor

    Does anybody have a next size up pilot jet to measure ? Up from these 27.5 originals. ?
    -R
     
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