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Butterfly screws removal xj700x

Discussion in 'XJ Technical Chat' started by Toyobaru866, Apr 10, 2021.

  1. Toyobaru866

    Toyobaru866 Active Member

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    Hi y'all,

    First let me introduce myself as I'm new on this forum. I'm from the Netherlands (so please forgive me my grammar). 20 years ago I bought my first motorcycle, a Yamaha Maxim XJ750X. Really loved this machine. In those days I've learned a lot about this bike at the micapeak forums. Some great guys as Jeff Mountain and Dwayne Verhey had great knowledge and were very helpful. Regretfully due to bad business and a divorce the last 10 years I didn't ride a bike. Last year I saw a 1986 700XS in nearly mint condition and I couldn't resist... Love the bike again!

    I did some basic maintenance to the bike as tyres, brakes, valve adjustment and replaced the coils for Dyna coils. It rides pretty good but a rebuild of the carbs was also on the list and that's what I'm doing write now. I love this site because of the great knowledge here and great info. I've read a lot about cleaning and rebuilding the carbs on this forum and on xj4ever to freshen up my knowledge.

    Now I've dissembled the carbs almost completely to do a thorough cleaning. I've ordered parts from Len, great guy, including the throttle shaft seals. Now here's the question (sorry for the long introduction ) what is the size screwdriver for the butterfly screws? I've bought a set of YIS screwdrivers. On a video a quy said to use number 2 but it seems to big as number 1 seems just a little to small. Sorry if this is a dumb question but I'm really afraid to strip those heads...

    Any help will be much appreciated!

    Cheers,
    Geurt
     
  2. Toomanybikes

    Toomanybikes Well-Known Member

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    You should use JIS not Phillips screwdriver for those screws and it it a #2
     
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  3. Franz

    Franz Well-Known Member

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    Are the butterfly screws peened on these machines?
     
  4. Toyobaru866

    Toyobaru866 Active Member

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    Thanks for the replies, I have JIS screwdrivers, so it's a 2. And yes the screws are peened. I file them down flush with the shaft.
     
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  5. lostboy

    lostboy Well-Known Member

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    You will find that every screw on a Japanese is not JIS. So try both style or screwdriver. Use a bit of valve lapping compound to aid in gripping the screw.
     
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  6. Toyobaru866

    Toyobaru866 Active Member

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    When I take a photo and enlarge it I can see the dot so that means it's JIS isn't it? Still my number 2 JIS doesn't fullfil me with confidence.. I like the idea of using a little lapping compound! Could it be my Vessel JIS screwdriver isn't top notch? It's new but maybe I should buy another one to check.
     
  7. xHondaHack

    xHondaHack Active Member Premium Member

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  8. Toyobaru866

    Toyobaru866 Active Member

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    Thanks Tony, I've ordered a set here in Holland and wait until it arrives. In the meantime I will clean the inside of the heads of the screws real good because I can see a little dirt there that maybe affects the grip of the screwdriver.
     
  9. Toyobaru866

    Toyobaru866 Active Member

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    For those who are interested, here's my experience with the removal of the butterfly screws. They are all out but not without a battle...

    After the arrival of my new JIS number 2 screwdriver I started the process.

    First I filed the back of the screws back to just a very little bit above the shaft. I think that works better than filing them down flush with the shaft (did this with the first 2 screws) because in my case it looked like the metal of the screws and the shaft mixed together creating some kind of a bond. I used a Dremel with a stone to do this.

    The first two screws were a learning process obviously the heads stripped and I had to drill out the first one. It's a wonder that the threads are stil ok to use. I started drilling out the second one when unexpectedly it came loose without any damage.

    The next 5 screws came out fine, now I used a counter support and gave the screwdriver a good wack for a better fit in the head. With good pressure on the screwdriver while turning they breaked loose just fine.

    The last one gave me problems again but I learned from the first 2 screws... This time I used a left drill bit number 2. I drilled it until the point that the head still had a little body. Then I used a number 3 extractor and it came out just fine! For me that's the way to do it when the head is stripped.

    Probably could have done it better but I'm glad they're out! Now for the cleaning!

    Regards,
    Geurt
     

    Attached Files:

  10. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    It's the good whack that does the trick, disturbing the threads and releasing enough of the seizure to make removal possible. This is also (usually) necessary on the upper and lower rack screws, too.
     
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  11. Jetfixer

    Jetfixer Well-Known Member

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    Personally , once I get the screws removed I replace with new standard metric fasteners on the carbs .
     
  12. Toyobaru866

    Toyobaru866 Active Member

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    Thanks.

    When assembling the butterfly's I was planning to use loctite 243. Is the following procedure ok?
    Placing the butterfly in the shaft en place the screws but not tightened. Set the butterfly so that it closes complete and rotates free. Also read somewhere to snap them to set, is that ok? Next loosen the screws one at a time to apply locktite and tighten them.

    Also one butterfly, the first one I took out, is slightly damaged , will that be a problem later? 16186905977896455796698846331599.jpg 16186907361012477242661629458.jpg
     
  13. Toyobaru866

    Toyobaru866 Active Member

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    Nobody? The more I read about the butterfly's the more I think I'm an idiot and ruined the number one I have an extra rack, should I replace the whole carb or can I use the butterfly off the other rack?
    Any help will be so much appreciated...
     
  14. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    You can probably just gently file the edges of that butterfly valve and it should be fine. The gouges on the "face" of the valve won't matter, it's just the sides and the edges which need dressing.
     
    Last edited: Apr 19, 2021
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  15. dkavanagh

    dkavanagh Well-Known Member Premium Member

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    I just replaced my butterfly valves yesterday. I cleaned up the screws I had previously ground down with the dremel, using a small flat file. I got the disks in, snugged screws and checked for light coming through. I also backed the screw mostly out, put a drop of blue locktite , then ran the screw in, then dabbed off the excess. Hoping that holds!
     
  16. Toyobaru866

    Toyobaru866 Active Member

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    Thank you Len, gives me some more confidence. Will try that and see how it goes.
     
  17. Toyobaru866

    Toyobaru866 Active Member

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    Glad to hear you you follow about the same procedure! I have new screws from XJ4ever so that should be fine. Now waiting for the carbs to return from the ultrasonic cleaning.
     
  18. dkavanagh

    dkavanagh Well-Known Member Premium Member

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    I got a couple replacement screws from Len as well. I ground those down to be the same length as the others I ground down. Gotta keep things even!
     
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  19. Toyobaru866

    Toyobaru866 Active Member

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    Consistency is a good thing
     
  20. Toyobaru866

    Toyobaru866 Active Member

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    Installed the carbs today. Started right up and idled without choke. Was in the shed so couldn't test more than that. This weekend for the running sync and colortune. Happy so far!
     

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