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Flat Spot off Idle

Discussion in 'The Garage' started by freddy3, Sep 7, 2020.

  1. grizld1

    grizld1 Grumpy old man Top Contributor

    I very much doubt that the throttle shafts from that kit would fit, and I'm very sure that the throttle plates won't be what you need. The kit is for Super BN carbs, which are used on jet skis with 2-stroke motors.
     
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  2. 5twins

    5twins XS650 Guru Top Contributor

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  3. freddy3

    freddy3 XS650 Addict

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  4. freddy3

    freddy3 XS650 Addict

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    Probably, more than I need (and I've perused a couple of them previously), but thanks for the links!
     
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  5. freddy3

    freddy3 XS650 Addict

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    Update...

    With the appropriate JIS screwdriver, three of the four throttle valve screws loosened without issues, but the fourth wouldn't budge after 48 hours in Kroil and heated with a heat gun. So I tried my trusty Sears Deck-Out, but, after repeated attempts, I've ground most of the screw's head off and it sill won't budge. Any suggestions for where to go from here...
     

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  6. 5twins

    5twins XS650 Guru Top Contributor

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    You'll have to carefully drill the rest of the head off and then you may be able to unscrew it from the backside, grabbing it with needle nose pliers. Or, if you switch to a drill bit slightly smaller than the screw diameter once the head is off, that may spin it out for you.
     
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  7. freddy3

    freddy3 XS650 Addict

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    Many thanks!
    The treading within the throttle shaft appears to be fully intact, but I wonder if all the pressure I had to bear on the shaft to drill out the screw might've bent the shaft?
    Due to my proclivity for losing small parts when sitting around, I'm hesitant to go further 'til I receive the new throttle shaft seals, which should be Monday or Tuesday.
     

    Attached Files:

    Last edited: Sep 12, 2020
  8. 5twins

    5twins XS650 Guru Top Contributor

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    So what did it? Drill bit spin it out or did you grab the back end with pliers?
     
  9. Jim

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

    If it moves freely in the carb body you're probably OK. You can also chuck it up in a drill press or hand drill and see if it wobble. Even the slightest bend will be noticeable.
     
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  10. freddy3

    freddy3 XS650 Addict

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    Both actually. I tried to turn it out with needle-nose before posting the request for help with the stripped head, but it wouldn't budge. There wasn't enough of the screw to get a good grip on. But after taking your advice to grind-off the head, I was then able to easily turn it out from the rear.

    Although I haven't yet removed it (waiting 'til the seals arrive to do that), any thoughts on whether I might've mucked-up the true of the throttle shaft with all the drilling?
     
  11. freddy3

    freddy3 XS650 Addict

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    I reckon it's alright then. I don't notice any difference in the shaft's movement within the body now versus before.


    I'm with you re the hand drill, but I was more concerned with whether there's a recommended process for correcting the true, if it's off?
     
  12. Jim

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

    Gentle taps with pieces of wood.... lotsa' beer and patience.;)
     
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  13. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    For this kind O work beer is best
    left as the victory drink.
     
    Last edited: Sep 12, 2020
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  14. Jim

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

    dogs drinking beer.gif
     
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  15. freddy3

    freddy3 XS650 Addict

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    Update...

    I received the Mikuni needle and throttle shaft seals today and I'm stuck at removing the seal under the metal cup--the side beneath the return spring. The other side came out with the shaft, but this one won't budge....at least not with a small flathead. Is it cemented or press-fit into the hole, or is there a special tool to remove it so I don't mar the hole??
     

    Attached Files:

  16. 5twins

    5twins XS650 Guru Top Contributor

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    No, they are supposed to be a rather loose and sloppy fit into the hole. They don't do their sealing from fitting tight in there but rather by the vacuum generated through the carb bore sucking them in tight. That's why they need to be soft and pliable to work properly. Old and hard don't cut it, lol. It appears someone may have glued that one in. I'd take some paint stripper to it. Maybe a couple 10 or 15 minute soakings will dissolve the glue or sealer used and allow it to come out easily.
     
  17. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

  18. freddy3

    freddy3 XS650 Addict

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    The good news: It looks like the same metalized seal.
    The bad news: You didn't explain HOW you pried the old seals out?

    Actually, because I'm working on this on my living room floor (live in a small flat without access to the facilities to make metal rings), I'm thinking I might be better off just tearing out the damaged rubber material (leaving the metal ring intact) and, then, just inserting a new [all rubber] seal INTO the existing metal ring. Any thoughts?
     
    TwoManyXS1Bs likes this.
  19. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Yeah, Mailman ran into the same steel-shelled seals.

    Start at post #282.
    http://www.xs650.com/threads/mailman’s-xs2-a-full-on-restoration.51520/page-15#post-544356

    In these pics, I show a washer that I used to lever against, to protect the carb metal. I just used an old, tiny screwdriver that I've ground down like a tiny chisel. Get behind the shell, and levered the seal out.
    71XS1B-Carbs-Seals01.jpg 71XS1B-Carbs-Seals02.jpg 71XS1B-Carbs-Seals03.jpg

    I had to completely remove the seals because I was going to re-bush the shaft bore...
     

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