How to change your main jets and needle valve.
Start by removing air cleaners from the tops of the carburetors. 
This will give you access to six screws on top of each carburetor.

Remove the top of each carburetor  but be careful not to damage
the gaskets as you will want to reuse them. The needle valve sits above
the float attached to the underside of the top half of each carb.Unscrew to
remove or replace. Now remove the float assembly which will consist of
three parts.

  If the carburetors have been recently used, there will be gas within the
float bowl.  Gas does not need to be removed as it will not leak when you remove the main jet.  The main jet is at the bottom of the float bowl.  It can be
removed with a flat head screwdriver, turning it counterclockwise.

  To install or reassemble, follow above directions in reverse.   Make sure to
remember to install the float assembly (as I have done this once or twice!!!).
< The float assembly