How to Adjust the Motorcycle Carburetors on a Honda 1100cc

Updated February 21, 2017

The Honda 1100cc road bike was produced in several models that include the older CB1100 series and the newer Shadow 1100 series. All have twin-cylinders and dual 36mm Keihin carburettors. A number of components comprise the fuel-related systems on your 1100cc Honda motorcycle. If the air filters and fuel filter are clean, and the throttle cable is in good shape, you can dial in performance by adjusting the carburettors. The first order of business is accessing the carburettors, located beneath the rider's seat. You remove the seat to adjust the carburettors on a Honda 1100cc motorcycle.

Park the motorcycle in a ventilated area. Pull the small plastic caps off the idle adjustment screws on the outside of the right and left carburettor by hand. Depending on the motorcycle, the caps may be black, red or yellow, and about the diameter of a dime. Put the caps on a workbench or out of the way to prevent them from getting stepped on or misplaced.

Turn the idle adjustment screw on the right carburettor clockwise with a screwdriver until is it is fully closed. Turn the screw counterclockwise 2 1/2-turns, which is the standard setting. Do the same with the idle screw on the left carburettor.

Start the motorcycle and allow the engine to warm up to its normal operating temperature. This should take about five minutes.

Locate the throttle-stop screw at the base of the throttle lever between the carburettors. Twist the throttle hand grip a few times and notice the throttle lever rotate up and return to the idle position.

Set up a 5mm socket on a socket extension and ratchet. Position the socket on the throttle-stop screw and observe the motorcycle's tachometer. Rotate the throttle-stop screw clockwise or counterclockwise until the tachometer reads 1300rpm.

Adjust the idle with the screwdriver, beginning with the right carburettor. Turn the idle screw slowly clockwise or counterclockwise in one-quarter increments as you listen to the engine speed. The idea is to set the idle adjustment at the point where the idle speed is peaked.

Turn the idle adjustment screw on the left carburettor clockwise or counterclockwise in one-quarter increments until you find the point where the idle speed is peaked.

Twist the throttle handgrip several time and allow the engine to return to idle speed. Note the tachometer reading. Turn the throttle-stop screw clockwise or counterclockwise with the socket and ratchet as necessary until the tachometer reads 1100rpm.

Turn the engine off. Reattach the rider's seat on the motorcycle. Take a test ride and note whether the engine's performance is smooth and consistent from a stop, and through each gear.

Readjust the idle settings on each carburettor in one-eighth increments: counterclockwise if the throttle response is slow from a stop, and clockwise if the response is slow when shifting up through the gears. Test-ride the bike after each adjustment. Reattach the caps on the idle screws when done. They should still be where you put them.


Altitude and temperature can affect carburettor performance. Talk to a motorcycle mechanic if carburettor adjustment does not improve basic performance. Websites like have additional carburettor information that may be helpful.

Things You'll Need

  • Screwdriver
  • Metric socket and ratchet
  • Socket extension
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About the Author

William Machin began work in construction at the age of 15, while still in high school. In 35 years, he's gained expertise in all phases of residential construction, retrofit and remodeling. His hobbies include horses, motorcycles, road racing and sport fishing. He studied architecture at Taft Junior College.