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Idle issues and exhaust popping

Discussion in 'XJ Technical Chat' started by Treads, Aug 6, 2010.

  1. Treads

    Treads Member

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    I've got my bike running finally, but I'm having a couple issues. Like the title says, I'm having issues with my exhaust popping at high rpms and can't get my idle right. I can get it to idle at 2k, but if I try to lower it then it slowly drops off and just dies. I'm running open headers until I can get it into the exhaust shop which should be a few more weeks. Could it be lack of back pressure causing it? I also checked the plugs and due to running a pvc manifold, I'm running lean. I'm gonna put the center section of exhaust back on for now to see if that helps. Any other ideas?
     
  2. mlew

    mlew Well-Known Member

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    Running lean will make the exhaust "pop". Get the exhaust finished up and then tune the bike. Meanwhile check those valve adjustments. Valves out can make it impossible to get a good idle.
     
  3. Treads

    Treads Member

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    Ugggh Those were the words I was dreading to read, but I do need to do that. Thanks for the info mlew.
     
  4. mlew

    mlew Well-Known Member

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    Get those valves adjusted first then the rest of the tuning is so much easier.
     
  5. Treads

    Treads Member

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    I've never done that before. I'm sure chacal has the parts I'll need, but what parts do I need to buy from him?
     
  6. mlew

    mlew Well-Known Member

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    You'll need a set of metric feeler gagues to start. Get those at a autoparts store. Some use a SAE set but it gets confusing converting the measurments. Get a service book and read through the valve procedure, it will tell you everything, Chacal might have these but I don't know. You will also need a valve cover gasket and valve shims.
    Get the feeler gagues and book first then order the gasket and shims you need from him. Get extra shims , don't cut yourself short. They do wear out and I have replaced shims with the same size and had the clearences go back to spec. So if you have a valve out of spec and there is a #270 shim in there entertain the possibility of replacing it with another 270 shim and rechecking. A valve shim kit is also a good idea but they run about 120$.
     
  7. iwingameover

    iwingameover Active Member

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  8. Treads

    Treads Member

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    Yeah I bookmarked that thread earlier and the work doesn't sound to difficult. Just dreading the cost. Hopefully Chacal will chime in with a low number on the cost. :p And I live in Hutchinson, KS Iwin.
     
  9. iwingameover

    iwingameover Active Member

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    Too far for me to lend a hand.

    Just got to measure and check your shim numbers.

    Valve cover gaskets, bolt donuts and whatever shims you need would be it.
     
  10. RickCoMatic

    RickCoMatic Well-Known Member

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    If you are running Straight Pipes and getting a lot of Backfire ...
    CHECK ... THE ... PLUGS!!!

    If the Plugs are Clean and the Center Electrodes Porcelain Insulator shows any evidence of Tiny Fractures surrounding the Plug Tip, ... you need to take measures to protect the Mill.

    Re-Jet
    Add a Top Cylinder Lube to the Fuel.

    The idea is to SLOW DOWN the Burn.
    A flashbulb-fast burn is too hot for the aluminum parts.
     
  11. Treads

    Treads Member

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    I'm gonna get the exhaust done asap to eliminate that problem. Hopefully my valve clearances are ok, but if not I'll have to do that. Is it possible that the spring on the idle set screw is just crap?
     
  12. gratscot

    gratscot Member

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    Yea the idle spring can where out.
     

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