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Idle issues

Discussion in 'XJ Technical Chat' started by Ronney L Henderson jr, May 25, 2018.

  1. Ronney L Henderson jr

    Ronney L Henderson jr Member

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    I have a 82 xj550 maxim that I got next to nothing. I rode it home last year from where I got it from. But the choke had to stay on. Over the winter I rebuilt the carbs . I did replace 1 pilot jet and all the valve needles( I believe that what there called. New fuel and fuel lines and vacuum line to the cock pit. Cleaned the it . New plugs ,adjusted the float height. The slides work the same so no issues with that.

    Started it up have the idel set to just under 1500rpms. After it warms up (About 10 mins).

    So here is my little problem . With the choke open at 1st start up its at 5000. Is this common? If not how do I take care of it ? After it warmed up the choke is off idling just under 1500rpms. I give it some gas as the ideal comes back down it wants to hang out at 2500rpms for a minute or so. I have check all cables nothing is binding . Oh I did also sync the up with vacuum gages.

    Ps I know my grammar suck lol

    Thank for the help.
     
  2. fastenova

    fastenova Member Premium Member

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    First thing I'd do is check for vacuum leaks - you can use an unlit propane torch on low and waft it around the intake boots, airbox boots, and throttle shaft - these are the most common places to leak - and if the revs go up, you know you have a vac leak. Or you can use carb cleaner or starter fluid and spray around the same places. Just wipe it off any surfaces when you're done testing to prevent any discoloration of the rubber.

    Also make sure that your vacuum line coming off carb #3 (or one of the others) is plugged into your fuel petcock, or at least plugged if you have issues with the petcock, and the others are plugged with a rubber cap. 1500RPM is a bit high, should be closer to 1000RPM.
     
  3. Ronney L Henderson jr

    Ronney L Henderson jr Member

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    Thanks will do a leak test. Will keep posted
     
  4. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    Did you break the rack?
    Did you replace the throttle shaft seals?
     
  5. Xjrider92117

    Xjrider92117 Active Member

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    Did you fully disassemble the carbs when you rebuilt them? If not your probably gonna have to do it again and replace all of the rubber orings and seals.

    You set the floats but did you do a wet set?
    Here's a link on that if you didn't.
    http://www.xj4ever.com/setting fuel levels.pdf

    Also, did you sync the carbs after the rebuild?
    If not, that will cause an idle issue.

    I'd visit the church... Helped me a lot.
    https://xjbikes.com/forums/threads/in-the-church-of-clean.14692/

    And if you really want to read something here ya go!
    https://xjbikes.com/forums/threads/the-information-overload-hour.27544/

    Hope this helps!
     
  6. XJ550H

    XJ550H Well-Known Member Premium Member

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    with choke on the rpms will climb to 5000rpm. the "choke" is an enrichment circuit. it dumps fuel into the carbs. try setting to 1/2 choke or none at all when starting.
    I only need to use choke in cold weather.
    set your idle to 1200 rpm the spec is 1050rpm but 1200 eliminates the chain slap sound.
    make sure the enrichment plungers are closing when you shut the choke off ,push down on them.
    are you using stock paper air filter?
     
  7. Ronney L Henderson jr

    Ronney L Henderson jr Member

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    No I did split the carbs. I did set float to 21.5mm. Just a a paper filter. Got it running with the idle down to about 1200rpm rides it for about a half hour no issues. . Yep drop here in northern Michigan. Now it will not fire up getting spark and fuel and it does have a new battery .
    Thinking maybe weak spark??
     
  8. XJ550H

    XJ550H Well-Known Member Premium Member

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    setting floats is just the beginning of setting fuel levels you need to check the wet level and set properly

    Setting the fuel levels

    what happens after a half hour?

    keep battery charged if it drops below 10 volts when cranking bike will not start. even new battery can be bad.
     
  9. Ronney L Henderson jr

    Ronney L Henderson jr Member

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    Battery is fine . It turns over very well. The only thing that happen after I rides it last is that it rained hard for a day. Going to check the spark if cap. Making sure it's getting good connection.
     
  10. Ronney L Henderson jr

    Ronney L Henderson jr Member

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    Well I did some inspecting of the coils.and found this. . Could I epoxy it for a short until I can get a new one? And I will be getting a new one here shortly. And should I just do both at the same time
     

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  11. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    You can epoxy it forever. We used to do that when there were no alternatives.
     
  12. Ronney L Henderson jr

    Ronney L Henderson jr Member

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    Ok have new plugs again and new coils plus caps. Fires up again . But still a hanging idle. Going to propane test this weekend. Check for leaks. Never wet tested float height as I understand that it needs to be 3mm below the top of the fuel bowl. Now will that cause a hanging idle??.
    Will a air leak from where ever show on plugs. As rich or lean? Plus should I polish the slides ? They do seem to move alright and about the same.

    I am all ears.
     
  13. Chitwood

    Chitwood Well-Known Member

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    Sounds like a vacuum leak to me. Vacuum synch? Colortune?
     
  14. Ronney L Henderson jr

    Ronney L Henderson jr Member

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    Well just did a wet test after about 10min riding it. And yes I did let it warm up I was ravening up to drop the idle down and then stall out and I just can't get it adjusted happy medium to get it to run did Chuck what test it supposed to be 3 mm from the top of the lower fuel bowl I'm about Lovin would that have anything to do with it
     
  15. Ronney L Henderson jr

    Ronney L Henderson jr Member

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    Well just did a wet test after about 10min riding it. And yes I did let it warm up I was ravening up to drop the idle down and then stall out and I just can't get it adjusted happy medium to get it to run did Chuck what test it supposed to be 3 mm from the top of the lower fuel bowl I'm about Lovin would that have anything to do with it
     
  16. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    The fuel height affects the ability of the jeets to pick fuel up from the bowl. Too low will cause a lean condition.
    The float bowl levels are supposed to be checked with the carbs on the bench, and fully level.
    setting fuel levels.pdf
     
  17. Ronney L Henderson jr

    Ronney L Henderson jr Member

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    Ok did a wet test for float height. I am 11mm from the top of the bowl. I know it needs to be 3mm .
    Could that be apart of my issue . Goi my to rest set it later to day . But before that I want to leak test it with propane.
    Since I will be taking carbs out again. I should polish up where the slide goes.
    Anything else I should do ?
     
  18. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    Heck yes that's the problem. No wonder she's lean.


    Under no circumstances should the slides be polished. There is a coating that has to stay on them, and it's very thin. Pull the top hats. Lift the slides until they don't quite clear the top of the bore, then let go. If they go 'clunk' then everything is fine. If they stick, or slide down slowly, then you can take some 800 grit wet-and-dry and clean up the bore (not the slide).
     
    Last edited: Jun 8, 2018
    Jetfixer likes this.
  19. Ronney L Henderson jr

    Ronney L Henderson jr Member

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    Time to rip apart again lol. But I want this bike to run right.
     
  20. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    All you need to do is adjust the float heights at this point. Don't make any other changes until you've ran her with the fuel levels set correctly.
    There might still be something else that needs tended to, but you'll jsut be grasping in the dark unless you tackle one thing at a time and confirm what effect it has.
     

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