When removing rust from the fuel tank, thoroughly clean the fuel cock and fuel gauge as well. A motorcycle's fuel tank that has been stored outdoors for a long period of time suffers from rust due to deteriorated fuel and moisture in the air to some extent.
It is not unusual for the fuel tank to rust even if it has a roof in a parking lot with poor ventilation. When restoring such a fuel tank, you must pay attention not only to the fuel tank itself but also the parts that attached to it.
The fuel cock, as well as the corrosion of the gauge on models with a fuel gauge, should be checked.
How to prevent rust from the fuel tank?
If the fuel tank rusts, the rust and dirt are flowing into the fuel cock, even if the engine is not running. You probably won't start the engine in this condition, but if you operate the fuel cock lever, dirt will act as an abrasive and wear the gasket.
"What to do with the fuel in the fuel tank?" is a difficult question when you won't be riding a motorcycle for a long period of time (or can't ride). There are several opinions on this, such as that fuel left in the fuel tank halfway through will rust the exposed inner surface due to temperature differences and condensation caused by humidity, so it's better to fill it to the very edge of the fueling port, or empty it and spray it with anti-corrosion lubricant.
Some proponents of keeping fuel in the fuel tank are of the opinion that it is better not to fill it up because biofuel, which is becoming more and more popular, tends to combine with moisture. In such cases, adding a chemical called a fuel anti-degradation agent can prevent fuel from spoiling and rusting. If you don't pay attention to it at all and leave it for a long time, fuel degradation that produces a strong odor and relentless rusting will occur.
If you want to prevent rust, draining the fuel from the fuel tank completely, removing the fuel cock and storing it in a dry place with the tank cap open may be safer than leaving it in the fuel tank.
Once the fuel cock is removed from the fuel tank, disassemble it and soak it in carburetor cleaner to remove the dirt. Any dirt that gets stuck in the pipes should be completely removed with a brush or pick tool.
The rubber part on the left side of the fuel cock is a new replacement part. The diaphragm of the negative pressure fuel cock is sold by piece with the fuel cock assembly.
- What to do with the fuel of the fuel tank during long-term storage
- You can either inject the anti-fuel degradation agent or remove it completely.
Is fuel gauge corrosion more troublesome than rusting the fuel tank itself?
When I removed the cover of the sliding resistance with the copper wire wrapped around the substrate, I found that a large amount of sludge-like dirt had accumulated on the inside as well. I'm glad that I can disassemble it so far, but it's a pretty tough situation if it's not disassembled. While soaking it in fuel or kerosene, I used a brush to steadily remove the dirt.
If the inside of the fuel tank is covered in rust, the fuel cock attached to the fuel tank will naturally be covered with rust as well. In the case of motorcycles with a fuel gauge, the fuel gauge unit, which measures the amount of fuel remaining in the fuel tank, also needs to be addressed. Furthermore, a fuel-injected motorcycle with a fuel pump in the fuel tank are more likely to be damaged.
The fuel tank shown in the photo is from a carbureted motorcycle, but it is equipped with a fuel gauge and is covered in severe rust. The fuel gauge, which combines a float and a sliding resistor (sliding volume), is a basic type of fuel gauge, and the current flowing through the resistor changes depending on the position of the moving contacts on both floats, and the magnitude of the current moves the fuel gauge pointer.
The fuel gauge is clinging to a paste-like mixture of deteriorated fuel and rust on the inside wall of the fuel tank, and spraying the gauge with parts cleaner will not remove any of the dirt.
Since current flows through the gauge, it is not possible to use the gauge with rust on the resistance part, and if you use the gauge with grease like dirt on the inside of the fuel tank, the dirt will continue to seep out and may cause new rust even if you remove the rust from the fuel tank itself.
Therefore, disassemble the gauge unit as much as possible, dip it in fuel or kerosine and clean it with a brush.
- The fuel cock must be cleaned when removing rust from the fuel tank.
- Check the fuel gauge for models with fuel gauge
Open and wash carefully to the point where it can be disassembled
When there is a lot of fuel in the fuel tank, the float position becomes high. Since the resistance of the sliding resistance is small and a lot of current flows through the fuel gauge coil, the needle of the fuel gauge indicates a full tank state.
When the fuel in the fuel tank is low and the float is lowered, the resistance value increases. As the current in the fuel gauge decreases, the needle wavered less and the remaining amount of fuel was indicated.
The fuel gauge for the KAWASAKI ZEPHYR, which looks as if it was dug out of the mud, has a protective cover over the sliding resistance part, which is the key to showing the amount of fuel, and the cover is removed by raising the claw. Soak the gauge in fuel and scrub it gently with a toothbrush, enduring the strong odor of rotten fuel, and carefully remove all the dirt as the copper-wire wrapped resistance is revealed underneath the dirt.
It depends on the structure and mechanism of the gauge how much it will be disassembled, but it is better to remove the bolt-on parts as much as possible before cleaning.
Once you've cleaned and rinsed it, you should also check the function of the gauge. The procedure is simple: measure the resistance of the gauge wiring. It's hard to say what the resistance will be in the full and out-of-fuel positions, as it varies from model to model, but at least if it varies with the float position, it's working as a gauge.
The gasket, which has lost its flexibility and becomes stiff, must also be renewed at the time of restoration due to being sandwiched between the fuel gauge and the fuel tank. Be sure to perform maintenance on the relevant components as well when removing rust from the fuel tank.
- Soak it in fuel or kerosene and clean it off with a brush.
- Verify that the resistance value changes depending on the float position.