How do I adjust carburetor ON A JOHN DEERE RX75 RIDING LAWN MOWER

This method involves looking at the base of the spark plug insulator (white part of the plug) for a slight coloring on the insulator just above where the insulator comes through the steel case. If the mixture is too lean, it will leave no color, while a rich mixture will cause the fuel ring to become more prominent.

The stoichiometric mixture for a gasoline engine is the ideal ratio of air to fuel that burns all fuel with no excess air. For gasoline fuel, the stoichiometric air–fuel mixture is about 14.7:1 i.e. for every one gram of fuel, 14.7 grams of air are required.

With engine running:

Spray down and around the carburetor throat to remove deposits from the throttle plate area. Do not spray down carburetor throat with engine off. Do not spray below throttle plate.

Use Carburetor Cleaner

Fortunately, you can generally do this without even taking the carburetor out of the engine. Start by purchasing some commercial lawnmower carburetor cleanerOpens a new window, which comes in a simple spray can and will make it easy to clean the inside and outside of the carb.

The engine should rev smoothly and quickly as soon as you apply throttle. If the vehicle is displaying any sort of sluggish performance or misfires when you apply the throttle, then more adjustments are required.