How to Adjust the Carburetor on a Harley

Written by jeremiah blanchard
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How to Adjust the Carburetor on a Harley
The carburettor on most Harley motorcycles is still the classic Linkert carburettor. (moteur de Harley image by fxprod from

A Harley Davidson motorcycle is a classic iconic representation of the American biker. Owning one of these motorcycles requires periodic maintenance and tuning, such as adjusting the carburettor. The carburettor on most Harley motorcycles is still the classic Linkert carburettor that has been used for generations, though upgraded carburettors are available for some modern bike models. The carburettor can be adjusted using ordinary tools.

Skill level:

Things you need

  • Flathead screwdriver

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  1. 1

    Ensure that the Harley is in a safe position to work on and that the bike is upright and adequately supported.

  2. 2

    Locate the high-speed needle. This is the largest screw on top of the carburettor and is slightly protruding from the carburettor. Turn the high-speed needle on the carburettor inward until it just barely touches the carburettor with a flathead screwdriver. Turn the needle back by two full rotations.

  3. 3

    Locate the low-speed needle. This will be protruding near the carburettor base and is "L" shaped, making it easy to turn. Turn the low-speed needle inward until it just barely touches the carburettor. Turn the needle back by five full rotations.

  4. 4

    Set the Harley ignition spark to one mark shy of a fully forward position. The ignition timing mark is visible in the inspection hole located near the flywheel on the front cylinder. Start the Harley engine and let the bike idle until normal operating temperature is achieved. This should take 3 to 5 minutes.

  5. 5

    Ensure the throttle is closed completely. Turn the low speed needle clockwise by one click at a time until you notice the engine misfire. Immediately turn the needle counterclockwise by five to 10 clicks, or until the engine starts stops misfiring and runs normally.

  6. 6

    Turn the throttle stop-screw --- located on top of the throttle lever --- counterclockwise to make the engine idle between 900 and 1100rpm. Counterclockwise rotation of the stop-screw will reduce the idle speed.

  7. 7

    Repeat the steps until your engine is running smooth or if you continue to notice engine misfire.

Tips and warnings

  • Once the carburettor is adjusted correctly you'll hear a slower but smoother sound as your engine runs, uninterrupted by misfire or popping sounds.
  • Do not set the idle speed lower than 900rpm. This can cause engine problems.

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