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Pilot screws on non calif 86 zl600 and other q’s

torontobikeguy Nov 7, 2019

  1. torontobikeguy

    torontobikeguy New Member

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    I’m reading the threads and getting that to start I gotta change the gas. My bike idles low on both prime and on so I guess the fuel switch works on both modes. But why would the revs go up when I blow in the carb vent hoses and when I turn the throttle it cuts out? The carbs and jets are cleaned but should I look at the prime screw? Where is it and how many turns out ? 3.5? Would old spark plugs cause it to sputter and die under gas ? What does the decel cable do? What are the vacuum ports for on the carbs?
     
  2. Trojan441

    Trojan441 Well-Known Member

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    You are sure you have no air leaks! In a rush but I will get back to you! Screw all the way in then Pilot/mixture screw 2 to 2 1/2 turns out!
     
  3. torontobikeguy

    torontobikeguy New Member

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  4. torontobikeguy

    torontobikeguy New Member

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    OK where do I find the pilot screw on the 86 and where would I look for leaks typically.
     
  5. R. J.

    R. J. Supporting Member

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    :hello: Do you mean fuel mixture/air enriching screws. They are on the bottom center on the back of the carbs just behind the float bowls. Typically the float bowls O-rings leak. The floats neddle sets can wear causing the float bowls to leak.
     
  6. Trojan441

    Trojan441 Well-Known Member

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    Screenshot at 2018-08-30 14:55:21.png Screenshot at 2018-08-06 14:14:16.png My-Keihin-CVK-Carb-Settings.jpg

    First 2 images ZL Manual, other image Keihin Carburretor showing parts n' adjustment they haven't changed that much in 25 years!
     
  7. Trojan441

    Trojan441 Well-Known Member

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    Test for air leaks when the bike is running, leave it ticking over, ( of a sorts), then spray over carb's a squirt of Cod/Damp start, if the RPM rises whilst not touching the Twist grip, you have an air leak!
     
  8. Ed

    Ed Well-Known Member

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    Are all four headers getting hot when it idles?
     
  9. torontobikeguy

    torontobikeguy New Member

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    Makes sense . I will try with wd40 to see if the revs change. I know the guy I bought the bike from put fresh seals in the float bowls. Perhaps the boots are cracked. Had me thinking that when I blew in the carb vents hoses I must have richened the mix enough for the revs to pick up. I will have to wait until later to try.
     
  10. Trojan441

    Trojan441 Well-Known Member

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    When you say headers, I presume you mean exhaust pipes, again test with a wax crayon, touch them n' if it melts they are hot!
     
  11. torontobikeguy

    torontobikeguy New Member

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    Pinched fuel line
     
  12. torontobikeguy

    torontobikeguy New Member

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    Simple problem. I had to head out with family but will update Monday
     

    Attached Files:

  13. Trojan441

    Trojan441 Well-Known Member

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    That's one annoying problem with the ZL's very little clearance under the petrol tank for good fuel line vacuum pipe runs n' HT Lead routes!
     
  14. R. J.

    R. J. Supporting Member

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    Trojan441 likes this.
  15. torontobikeguy

    torontobikeguy New Member

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    OK. I dumped the old gas in the tank. Put in fresh 91 octane. The fuel line to the petcock was kinked. I fixed it. It still only runs on choke and when I try to apply throttle it dies. but when the new fuel started to get in the bowls the revs started to hunt on idle then went up from 2k to 4k . I tried using the penetrating oil test to search for vacuum leaks. There was no bogging down so I think it's good for vacuum. All vacuum lines are connected. I'm going to take off the carbs tomorrow to take a better look. I noticed though that when it warned I heard a tin popping sound in the right muffler once so I shut the bike off . The exhaust was smoky looking when it started to rev up. Right before the pop. The engine was warm to to touch.
     
  16. 87kawzl

    87kawzl Supporting Member

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    Valves out of adjustment will cause it to run crappy or not run at all.
     
  17. torontobikeguy

    torontobikeguy New Member

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    I was wondering about it. I will check the manual and get a measurement tool. I gotta change the oil and plugs anyways.
     
  18. ZipRoar

    ZipRoar Active Member

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    Pilot jets not clean enough. Running too lean and getting 'lean hang' at idle. Need to go through again. IMO.
     
  19. Ed

    Ed Well-Known Member

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    I don't know what vent tubes you're talking about but if the emissions crap is still attached, you should get rid of it and plug all the lines. If you don't, you'll be chasing gremlins. Mine would only start on full "choke", shoot up to 5000 rpm and die if I tried to back it off.
    They're used to sync the carbs and one is also used to open the fuel valve. Cap all but that one.
     
  20. torontobikeguy

    torontobikeguy New Member

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    OK. Now all I need to figure out is how to pull the carbs off with below freezing weather up here. Cold rubber hoses won't cooperate . Lol
     

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