1. Float valve stuck open. The float valve is responsible for regulating the flow of fuel into the carburetor. If it becomes stuck open, it can cause fuel to overflow and pour out of the bypass hose.
2. Float needle worn or damaged. The float needle is a small needle that seats against the float valve to stop the flow of fuel. If it becomes worn or damaged, it may not be able to seat properly, allowing fuel to leak past.
3. Float bowl cracked or damaged. The float bowl is the chamber in the carburetor that holds the fuel. If it becomes cracked or damaged, it can allow fuel to leak out.
4. Carburetor vent line clogged. The carburetor vent line allows air to escape from the carburetor. If it becomes clogged, it can cause a vacuum to form in the carburetor, which can pull fuel out of the bypass hose.
To diagnose the problem, you will need to inspect the carburetor and its components. If you are not comfortable doing this yourself, you can take your bike to a qualified mechanic.
Once you have diagnosed the problem, you will need to repair or replace the faulty component. If the float valve is stuck open, you may be able to clean it or adjust it. If it is worn or damaged, you will need to replace it. If the float bowl is cracked or damaged, you will need to replace it. If the carburetor vent line is clogged, you will need to clean it.
Once you have repaired or replaced the faulty component, your bike should no longer leak fuel out of the rear top right side bypass hose.
