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Need Carb advice

Discussion in 'XJ Technical Chat' started by 82SecaStooge, Aug 21, 2010.

  1. 82SecaStooge

    82SecaStooge New Member

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    I have an 82 650 seca, when i bought the bike it only ran on 2 cylinders. I took the carbs apart, cleaned then, and put them all back together. now it's running on all 4. a friend had a synchronizer, so we proceeded to adjust the carbs, was running fairly decent. If you twisted the throttle fast there was nothing there, but if you turned it slower it was ok. So I took it to a motorcycle shop for some other issues and had my carburetors re-synchronized, fork seals & state inspection. I ran even better, but now at operating temp its idles at about 3600 rpm's, i have to turn the choke lever half way on to idle it down. Does anyone have any ideas on what could be wrong? Thanks for any & all ideas on this problem.
     
  2. Cmccully04

    Cmccully04 Member

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    hmmm sounds like the same problem I have been fighting with for a month
     
  3. 82SecaStooge

    82SecaStooge New Member

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    I'm wondering if it has something to do with the air screws.
     
  4. gratscot

    gratscot Member

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    I'm assuming you already tried the idle screw correct?

    Because I know on my bike the idle screw is really touchy depending on the heat. When I ended up doing is adjusting it to where I wanted it after a 15 minute ride down the high way(Because it imposable to get the thing to normal running temperature just going around the block) When Its not warm I just adjust the choke according.

    However I'm running seafoam through the engine now so that might help how touchy it is, you may want to try the same thing.
     
  5. iwingameover

    iwingameover Active Member

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    gratscot is on the money if you've checked the idle mix screws.
     
  6. 82SecaStooge

    82SecaStooge New Member

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    When i first fire it up it idles at about 600rpm
     
  7. iwingameover

    iwingameover Active Member

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    cold and with choke?
     
  8. 82SecaStooge

    82SecaStooge New Member

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    Cold with the choke on just to get the initial fire up then i put the choke in normal position
     
  9. iwingameover

    iwingameover Active Member

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    you got to let it warm up a bit with the choke on.

    What do the spark plugs look like?
     
  10. 82SecaStooge

    82SecaStooge New Member

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    only have about 250 miles on them.
     
  11. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    You're coming at the problem sideways and that isn't going to fix it.

    IN ORDER, no shortcuts:

    -check valve clearances, adjust if necessary.

    -HOW clean are the carbs? Do they pass the "clunk" test? Did you pull the emulsion tubes and clean the holes out?

    -Float levels checked using the "clear tube method," with fuel?

    -Once you've got the running vacuum sync done, then you can start tweaking mixtures; you really need a ColorTune for this. It can be done "by ear" and then a series of plug chops/plug readings, but a colortune makes it go so much easier.

    The question about "what the plugs look like" was related to mixture. Are they lily-white, or showing some nice tan color, or all sooty black? Age isn't the question, it's a good way to gauge what's going on in the combustion chambers.

    The 650 Seca should idle at 1050 rpm.
     
  12. 82SecaStooge

    82SecaStooge New Member

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    My motor does make some ticking noise, as for plug color will let you know. It has 23670 miles on it & have no knowlege of its's past.
     
  13. 82SecaStooge

    82SecaStooge New Member

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    Plugs 1 & 2 are a brownish black with a little white on the back of both insulators
    # 3 is all white # 4 is more black color. As for the carbs, just took them apart, cleaned them put them back together, got it to run on all 4. at that point it ran at high idle when up to temp. we synced them ourselves, idled more normal. then took it to the dealer to have them re-synced, back to high idle, this is where i stand now.
     
  14. iwingameover

    iwingameover Active Member

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    Follows fitz's steps. he knows what he's talking about.

    Maybe your dealer hosed the synch? If it ran good with your synch redo it. The black plugs are too rich and an all white plug is too lean. brownish black is just a bit rich depending on the age of the plugs.
     

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