What is the problem with oil leakage from the motorcycle carburetor drain pipe?
2 Answers
Here is the relevant introduction to oil leakage from the motorcycle carburetor drain pipe: 1. Foreign matter adhering to the contact surface between the needle valve and the valve seat: The needle valve and valve seat control the fuel intake, and their sealing requirements are strict, with high smoothness on the contact surface. If foreign matter adheres to the contact surface, it will cause poor sealing between the needle valve and the valve seat, resulting in oil leakage. Foreign matter mainly refers to impurities and condensed gum in gasoline. To avoid such faults, users should pay attention to regularly cleaning the gasoline filter and using high-quality gasoline. 2. Wear of the needle valve: During use, the needle valve is worn due to long-term erosion by impurities in the gasoline and contact with the valve seat; unbalanced adjustment at both ends of the float causes the needle valve to bear lateral force and wear. Wear of the needle valve leads to poor sealing with the valve seat and oil leakage.
My old motorcycle also had a carburetor fuel leak issue, and it took me quite a while to figure out the cause. The most common problem is actually the imperfect sealing of the float chamber needle valve at the bottom - either the rubber gasket has aged or debris got stuck in it. When you close the throttle, fuel drips from the tube because gasoline can't push the needle valve open. Also, cracked drain tubes themselves are quite common - plastic tubes become brittle after five or six years of sun exposure. Last week when I disassembled it to clean the needle valve, I found rust particles in the fuel - these tiny particles most easily get stuck at the fuel needle. For DIY repair, first turn off the fuel tank switch, use a hex wrench to loosen the drain screw to collect waste fuel, and after reassembly remember to check if the sealing ring is properly tightened.
