When do you know you need to jet your carb?

When do you know you need to jet your carb?

Take the plugs out and if they look clean you’re good to go. However, if you see black soot then you’re running rich – meaning you’ve got too much fuel – if you see white residue then you’ve got too much air flowing in or you’re running lean. You can also determine if you need to jet the carb based on how the bike rides.

How does the jetting work in a carburetor?

Below is a diagram with general pictures of some of the parts in a typical carburetor that affect jetting. The carburetor slide (or valve) has a cut-away and moves up and down within the bore of the carburetor to control the AIR flow through the carburetor venturi (see above).

What happens if you have too much air in your carburetor?

However, if your bike can take off in a sprint but lacks overall power, then you’ve got too much air. The carburetor consists of four components: As you can see the carburetor consists of several parts that work, sometimes in unison, to influence the mixture of fuel and air.

Why are my carburetors not working on my motorcycle?

Fixing Lean Mixtures. This condition is generally caused by the incorrect fitting of after-market accessories such as exhaust systems, air filter systems, or replacement carburetors of a different type or size. In addition, if the fuel level in the float chamber is set too low, insufficient fuel will be drawn through the main jet.

What should I do about my carburetor jetting?

Over this and some jetting changes might be needed. Typical adjustment can be achieved with a leaner (smaller numbered) Main Jet and a re-setting of the idle speed mixture for a quality idle at higher elevations.

Where are the Jets located in a carburetor?

Shown below is a typical carburetor. The jets are located in the bottom of the carb. Remove the 4 screws which attach the fuel bowl to the carburetor. Once the 4 screws are removed the main jet and slow (or pilot) jet can be removed.

Which is the last step in rejetting carbs?

Stationary adjustment (air screw/ fuel screw) The last step is adjusting the air mixture screw or pilot jet. This screw controls the air/fuel mixture when the engine is running stationary and helps the engine start smooth. Working on this little fellow can also indicate that your main jet is too big or small.

What’s the correct jet size for a 12mm carburetor?

Carburetor diameter (12mm) x 5 = 60 (or number it calculates) x 0.9 = sea level jet size Take 0.948 (Denver atmospheric pressure at 70 degrees) x jet size (60) = new jet size (56.88) round up 57 would be the proper jet size to start at for a stock scooter using a 12mm carburetor. the CF is correction factor. CF=1 for sea level, 70 degrees F.