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Need help with Turbo Seca carbs?

Discussion in 'XJ Technical Chat' started by aldfaa, Jun 10, 2007.

  1. aldfaa

    aldfaa New Member

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    I have a 1982 turbo seca that i'm having some issues with. I noticed when started cold. the exhaust head on #1 and #2 cylinder would stay cold long after #3, and #4 were hot. after a while 1 and 2 would get warm, but never hot. I gave up on it after a while, and let it sat for a year. While sitting it got fuel in the crank case and a big puddle of fuel and oil was on the ground under it. last weekend I pulled the carbs, cleaned them all up, check all rubber parts and found everything to be in good shape. Reinstalled the carbs. The bike ran okay after it got warmed up. Gat a YICS tool and tried to sync the carbs. At idle it only pulled about 8 psi? Now the bike will barely run? The only way to get it running is full choke and even then it only runs 20-30 seconds. I would love to see this bike back on the road, any help will be greatly appreciated!
     
  2. BlueMaxim

    BlueMaxim Active Member

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    To get that puddle under you bike the petcock had to be bad or left on prime so it should be rebuilt too. Easy way to check is to set it to "ON" and pull the fuel line. If fuel comes out the petcock then it is bad. Fuel should only flow without vacuum, (engine running) in the "PRI" position.
    Problem with the carbs could be the float valves. You don't mention that you changed these when you cleaned the carbs. I find it beneficial to colortune first after cleaning the carbs. With it running only for a few seconds I would screw the pilot mixture screws in and back them out 3 turns. See if this keeps it running.
    Be sure to screw the pilot mixture screws in gently so that when they bottom out you don't damage the fine tip.
     
  3. Nick

    Nick Member

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    I believe BlueMaxim ment to type "Fuel should only flow with vacuum in the PRI postion."
     
  4. aldfaa

    aldfaa New Member

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    I did clean the petcock and so far I have had no fuel in the crankcase. I did not replace any parts during the carb. cleaning. I just turned the pilot mixture screws out to 3 turns. The only way to keep it running is to have full choke on, but it will only idles at 1200rpm. It dies as soon as you try to shut off the choke, If you slowly shut the choke off while coming in with the throttle it will stay running but then soon as you let off the throttle it dies.
     
  5. ferret2

    ferret2 Member

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    Carbs need a rebuild,
    check valve needs to be checked,
    turbo petcock isn't vacuum operated
     
  6. KiwiXJ750D

    KiwiXJ750D Member

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    The Turbo is like the EFI, it does not have a pri position as these bikes have a electric fuel pump.

    Does the fuel pump work OK?
    The carbs need to be "white room" clean. The Turbo carbs are pressurised. Did you completely disassemble the internals of the carbs and made sure all passages are clean, made sure floats close off completely, set float levels?
    When you cleaned the carbs did you bench sync them, mixtures set at 2.5 to 3 turns out?
    Try re syncing without YICS tool?
    What do the plugs look like? Tried replacing them?

    Sorry for the 50 questions ;).
     
  7. BlueMaxim

    BlueMaxim Active Member

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    What I was trying to say is that the fuel will flow "without the engine running" in the pri position if the petcock is operating normally. It will flow in the on or res position but only if vacuum is applied to the petcock if operating normally. If it is malfunctining then fuel will flow in any position so long as there suffcient fuel in the tank. So if you remove your tank and fuel flows in the "on" position when you pull the fuel line then the petcock needs repairing.
    Unless or course the turbo has a different petcock than the other XJ's.

    Aldfaa, what you describe is normal for a cold engine, not normal for a hot one.
     
  8. KiwiXJ750D

    KiwiXJ750D Member

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    Yes the petcock is different. It has On and OFF and RES. No vacumm operation, does not need one, but a IN and OUT tube on the back. The Electric Fuel pump system supplys a return to the tank as delivery is pressurised. EFI model is the same set up as the Turbo.
     
  9. BlueMaxim

    BlueMaxim Active Member

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    Sorry, I screwed up. I was under the impression the petcocks were the same. Thanks for catching that guys!
     
  10. aldfaa

    aldfaa New Member

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    Is there a good website that shows the correct way to set up the mikuni carbs? This is my first time trying to set up multiple carbs. I adjusted the mixture screws out to 4 and set the vacum guages on it. warmed up at idle 1200 rpms it pulled 10. But again this was with full choke. even after it is warmed up if you shut off the choke it will die. All of the plugs were black with #3 being the exception it was grey. It seems as if its not always hitting on 2 of the cylinders, every once in a while it will get a suge for a few seconds.
     
  11. BlueMaxim

    BlueMaxim Active Member

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    Check the links section. There are some listed there under the DIY header.
     
  12. aldfaa

    aldfaa New Member

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    What it the single thumb wheel looking screw that is located on the airbox side of the carbs? All the manual says is that its set at the factory? That being said approx how far out should it be turned?
     
  13. KiwiXJ750D

    KiwiXJ750D Member

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    Idle speed? Is in in the middle of the rack?
     
  14. aldfaa

    aldfaa New Member

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    yes it is in the middle of the rack. I thought it was the idle but turning it either way made zero difference in the way the bike ran.
     

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