How to adjust for "lean or rich" condition?

Discussion in 'Motorized Bicycle General Discussion' started by Nomad, Aug 17, 2008.

  1. Nomad

    Nomad New Member

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    I have read a few posts regarding " too lean or too rich" .. I understand what that means but not how to adjust it. I know about the needle in the carb but not how to adjust that ... I have not taken the carb apart except for to install the throttle cable. Could someone please explain how to do this. I think my plug is on the dark side instead of the light tan it should be, what about gas mix as relates to lean or rich mixture?................. thanks

    Bob
     
  2. misteright1_99

    misteright1_99 New Member

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    For a new engine breakin period I would run what the supplier suggests as far as the fuel/oil mix, generally 20:1 of a quality 2 stroke air cooled oil. As far as the fuel/ air mix it is controlled by moving the needle up or down inside the slide of the carb. Moving the needle clip down/ raising the needle richens the fuel/ air mixture, and moving the needle clip up/ lowering the needle let less fuel in and therefore leans the fuel/ air mixture. Usually a good starting point iss the second notch from the top. Also a good idea to get a quality name brand spark plug, gap it at .020 to .025, and replace the spark plug wire and cap, it screws out of the CDI and is easily replaced at any auto parts store, just ask for a coil wire and cut it to length...

    Here is an excellent thread on the carb internals..........

    http://motorbicycling.com/f4/carburetor-pictures-how-install-rebuild-195.html
     
  3. Nomad

    Nomad New Member

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    misteright1_99,
    Thanks for the reply, that should be just the info I was looking for...
    Regards
    Bob
     

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