Conference vmszoo::rc

    
    
    
    
    
    
    
    
    
    
    
      I'll give it a shot: 
    
    
      1. Set your high end needle valve.
    
      2. Adjust the low end needle valve ( if needed ). 
       
            -  Only make adjustments a 1/4 turn at a time. Remember where
               you started form, in case you need to go back!
    
            -  Richen by turning the screw out counterclockise, lean it by
               turning it in clockwise (exception: an airbleed carb, then
               it is just the opposite. You can identify if you have an
               airbleed carb by checking for a tiny hole in the front of
               the carb. If there is a hole, it is an airbleed. Ex: an O.S.
               40 FP IS an airbleed carb. )
    
        
       Regarding how fast the engine should idle at, I can't remember an
    exact RPM, but usually its the lowest speed the engine will run
    reliably at, and throttle up without quitting ( once the low end is
    set ). Higher nitro fuel will also smooth out the idle a bit.
    
       Symtoms:
    
          Once the high end needle is set, bring the engine to idle, and
      then throttle up fairly briskly. If the engine quits while throttling
      up, generally, the low end mixture is too Lean. If it stumbles, but
      doesn't quit, it is generally too rich.
            
    
                                                         Good luck,

    3000 rpm is an acceptable idle, (tick-over - for the Brits..).
    
    Most carbs are affected by the bottom end adjustment so if you change
    the low end ALWAYS retest and set the top end last.
    
    
    E.

    Can the low end idle affect the ability of the engine to siphon fuel
    from the tank?
    

    No
    

But (not that I qualify to correct Charlie) it can reduce the pressure 
in the tank due to the drop in frequency of the pulses from the muffler.
That would affect fuel feed (albiet not exactly suction)

    If the carb is not holding the fuel in the line it is the carb design.
    (I have often seen this in Magnum and ASP's).
    
    It will not draw fuel if the throttle is closed. Usually you open up
    1/8 to get fuel through the line.
    
    E.
     

    BOY could I do something with Jim's note...........
    
    But, I'd give Eric palpatations so I'll be good. 8^)
    
    

Such restraint for a thursday. I'm impressed

    The method described in .1 will work just fine.  I would add a couple
    of points.
    
    You are looking for good low end to full throttle response.  I have
    always used this as a que that I am getting close to the desired idle
    setting.  It is important that you readjust the high end needle valve
    setting every time you adjust the idle setting.
    
    I would strongly recommend that you stop the motor between adjustments
    of the idle setting.  I have seen people adjust the idle setting with
    the motor running.  Risky.  
    
    I would also recommend waiting until the motor is fairly well broken in
    before you try to get too precise on the settings.  They will change
    slightly as the motor breaks in.
    
    When you have it set correctly it should, once warmed up, rev from idle
    to full throttle as quickly as you can move the throttle arm.
    
    Will
    
    

    Another key point is to give the engine plenty of time to adjust to a
    change in setting.  Go to full throttle, adjust the needle, then go to
    idle.  Let it idle at least 30 seconds then throttle up smoothly and
    quickly.  If it keeps slowing down at idle, the idle mixture is still
    too rich.  If it dies when you throttle up, the idle mixture is too
    lean.  When it's right, you should get very quick throttle response and
    a consistent idle that will hold for at least a minute.
    
    Charlie