1) Fuel mixture: Make sure that the fuel mixture is correct. The ideal ratio for a KX 125 is 32:1. If the mixture is too rich or too lean, the bike may bog down.
2) Spark plug: Check the spark plug to make sure it is clean and in good condition. A worn or fouled spark plug can cause the bike to bog down.
3) Air filter: Check the air filter to make sure it is clean and free of dirt or debris. A dirty air filter can restrict airflow and cause the bike to bog down.
4) Jetting: The jetting may need to be adjusted to suit your bike's specific needs. If the jetting is too lean or too rich, the bike may bog down.
5) Clutch: Check the clutch to make sure it is functioning properly. A slipping clutch can cause the bike to bog down under load.
6) Carburetor: The carburetor may need to be cleaned or adjusted. If the carburetor is not functioning properly, the bike may bog down.
7) Cylinder: Check the cylinder for any signs of damage or wear. A damaged or worn cylinder can cause the bike to bog down.
If you have checked all of these things and the bike is still bogging, it is recommended that you take it to a qualified mechanic to have it checked out.
