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Throttle Sticking

Discussion in 'XJ Technical Chat' started by Deathalo, Jun 29, 2010.

  1. Deathalo

    Deathalo Member

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    Hi all, I just recently put the carbs back on my 550 maxim after a good cleaning and syncing. The bike starts up fine but the problem comes when I try to give it some juice. When I pull the throttle a bit to rev up to about 5k it revs fine but then stays at around 4k. I figured out that it's sticking because when I push down on one of the sync screws the throttle pushes down a few millimeters and the revs go back down to a regular idle.

    So, what should I do about this, it never did this before I removed and cleaned the carbs. I'm pretty sure the cable isn't caught on anything from looking at it while reving. I don't think there's any less slack than before and I don't know why there would be. It just seems like the springs aren't doing there jobs well enough or gravity isn't at least :p

    Thanks,
    -DH
     
  2. Deathalo

    Deathalo Member

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    Anyone have any ideas how to get the throttle to come back down? I can't really ride it when the RPMs stay at 4-5k after a rev. Is it possible it's not supposed to go all the way down and I need to adjust my pilot screws? I heard some sputtering the first time I started her up after I put the carbs back on, could it be too lean? If I back out the pilot screws some will it lower the revs without me having to push down on the mixture screws? Thanks.
     
  3. wizard

    wizard Active Member

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    A couple of thoughts, if you had the butterflys off, they could be catching, it only needs one, also make sure the screws / clamps on 2 & 3 boots at the front are not catching on the throttle quadrant.
     
  4. Deathalo

    Deathalo Member

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    I don't think the butterflys are catching, they moved and smoothly before I put the carbs back on. When you say throttle quadrant do you mean the connecting piece on the end that connects to the cable? If so, it doesn't look like it's catching anything that I can see. Could it be something a little WD-40 could fix?
     
  5. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    NO WD40! WD40=BAD. Gums up under heat.

    Do your carbs pass the "clunk test?"

    Did you bench sync the carbs before reinstalling?

    Check float levels using the clear tube method?

    Hanging revs generally indicates an out-of sync condition, or a sticking slide. Once you've confirmed the floats, and done a bench sync, then you will need to do a running vacuum sync to get it 100%.
     
  6. handyman

    handyman Member

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    take throttle cable off and lube up the inside of cable. Probably gummed up.
     
  7. Deathalo

    Deathalo Member

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    What exactly is the "clunk test". I did bench sync the carbs before putting them back on using the business card method as accurately as possible, so I know those butterflys are in sync. I didn't do a running sync yet because of this problem and I don't know why it would have something to do with the sync considering the revs only jump when i pull the throttle and don't come back down all the way unless I push down on a sync screw (and subsequently the throttle mechanism.) That's why I thought it's just the throttle stuck, I can lube the throttle cable, ironically that's the only cable I haven't lubed yet.

    One thing I noticed on my carbs, a loose spring attached to the sync screw between 1 & 2 that attaches to the underbelly of the carbs. I didn't know what it was for when cleaning, so I just put it back where it was. I think it might be rubbing up against one of the rubber boots going into the engine. Any of you know what this might be for? I'm thinking it might be something the PO added, hell maybe it's to pull the throttle back down all the way and it's just not doing its job. I'm going to see if I can fiddle around with it to stop it from rubbing up against the boot and I'll get back to you guys, I'll put up pictures of it too.
     
  8. iwingameover

    iwingameover Active Member

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    The clunk test is the slide pistons. YOu take the hat off and remove the spring. Push the piston up with your finger through the airbox side of the carb then release. It should slam down with a clunk. If it does not your pistons and or bores are dirty or worn.

    If pressing down on one of the synch screws helps your problem the carbs are out of synch and causing one to have part throttle. On these bikes one carb with part throttle equals all carbs with part throttle.
     
  9. Deathalo

    Deathalo Member

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    Ok so problem solved, I removed that weird spring thing and whadayaknow, throttle doesn't stick anymore, thanks a lot PO!! Here's what it looked like:

    [​IMG]

    Anyways, I decided I'd check my plugs to check the rich/leanness and here's what all 4 looked like:

    [​IMG]

    [​IMG]

    I'm thinking pretty rich? So I should turn each pilot screw clockwise a bit while the engine is idling correct? How much should I turn and how will I know it's right without waiting to check the plugs again. Thanks.
     
  10. iwingameover

    iwingameover Active Member

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  11. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    -float levels first. If you have a mis-adjusted float, you can't "tune it out" using the mixture screws, it will always be rich. (If set too high.)

    -bench sync.

    -THEN start messing with mixtures.
     

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