Launched as an export-only model for the North American market, the Super Cub was named the "Passport" instead of Super Cub. With the same large, square blinkers as the XL125 and the two-tone W seat, it had a stylish design that set it apart from the business-oriented Super Cub. After nearly 40 years, the Passport returned from North America, and I noticed "light rust" on the inside of the fuel tank. It's important to take care of rust as soon as possible, so let's get rid of it.
- Export version with double seats as standard equipment
- I noticed the "rust powder" when cleaning the carburetor.
- I doubt it's inside the fuel tank.
- High-Performance Rust Remover Chemical Hanasaka G
- Rust Remover Activated by Warming
- Gargle washing with long nozzle air gun
- Dry the inside and finish the work
Export version with double seats as standard equipment
The main feature of the standard stock W seat is that it is short for a W seat. The Super Cub series, which was sold all over the world, had many derivative models, including the Saddle (Japanese Cub), a single-seater semi-double, a passport-sized double, and a longer, stock double seat for Southeast Asia.
I noticed the "rust powder" when cleaning the carburetor.
I guess the engine had not been started for many years. The inside of the tank was empty and no fuel flowed out when the carburetor drain was loosened. First, I disassembled the carburetor and checked the inside. Then, the strainer part of the fuel cock assembled to the carburetor body, and the bottom of the float chamber was covered with rust powder that could be visually checked. You can also use a magnet to determine if it is rust or sludge.
I doubt it's inside the fuel tank.
The fuel tank can be easily removed by removing the double seat and loosening the bolts that are tightened to the frame. Since the fuel cock is attached to the carburetor body, the only thing on the fuel tank side is the two pipe nozzles where the fuel tube is inserted. To prevent the liquid inside the tank from flowing and leaking, a tube is connected between the two pipe nozzles coming out of the tank to prevent leakage.
High-Performance Rust Remover Chemical Hanasaka G
Hanasaka G Tank Cleaner is a highly successful fuel tank rust removal chemical. It is neutral, so it is easy to dispose of waste liquid, and it is harmless to humans and animals. Hanasaka G Tank Cleaner is a bionic chemical that removes rust from fuel tanks. It is a one-component product, and after treatment, the metal surface is coated with an anti-corrosion film, which prevents rust from occurring again.
Rust Remover Activated by Warming
Since the rust was not severe but only lightly rusted, 30 times dilution was sufficient. I split the tank cleaner in 50-60 degrees Celsius lukewarm water, poured it into the tank, capped it, and put it in the Carvek CV Junior (Super Cub type tank will fit!). I set the timer to 70 degrees Celsius, comparing it to the actual thermometer. The timer was set for one hour, so I turned the dial and repeated the process for a few hours while checking how the rust was coming off.
If it's thin rust, 20x. If it is rusty, I use 10 times dilution of Hanasaka G Tank Cleaner. After 4 hours of using CV Junior, I poured the treated liquid into a bucket and inspected the inside of the tank, and found that the rust was already removed and the tank was shining. The treated liquid was collected in a polyethylene tank while filtering out the debris. To our delight, the Hanasaka G Tank Cleaner can be used over and over again until the performance of the treated liquid declines.
Gargle washing with long nozzle air gun
After pouring out the processing liquid from the tank, stick in the water hose and wash the inside of the tank with an air gun and a long nozzle as if you were gargling, and the dirt and rust will flow out at once. It is really efficient to put a transparent plastic umbrella and work through the plastic because you will get soaked by the spray back from the tank inlet. I used a flashlight to visually inspect the inside of the tank. The light rust that I was worried about was almost gone, and the shiny iron plate part was shining as it was. This is a relief!!!
Dry the inside and finish the work
It can be completely dried by putting it in CV Junior and warming it up for 10 minutes. Here, I used a heat gun to dry it. Since the tank is small, the inside will be dry in no time. If you want to dry the tank naturally, dilute the tank cleaner solution with 3 to 5 times water, put it in the tank, spin it around, then drain it and let it dry naturally. This is called "rinsing," and it will prevent rust from recurring.
- Point 1: If you find dust accumulated in the carburetor, suspect the dirt inside the tank.
- Point 2: You are lucky if you can find even thin rust in an early stage. Let's use a tank cleaner to remove the rust.
- Point 3: The rust removal is activated by using lukewarm water instead of cold water for the tank cleaner.
- Point 4: Wash tap water thoroughly after treatment. Use an air gun in combination to ensure that dirt is washed away. Drying after work should also be done thoroughly.
The Passport has had rough maintenance work done, with the first priority on stable engine start and test ride. Although we had some doubts, our desire to ride the motorcycle won out and we proceeded with the maintenance. With relatively easy maintenance, we were able to ride. However, after a while of riding, an overflow occurred. I thought, "What? I thought, "Hmmm!" so I removed the strainer built into the fuel cock, which is integrated into the float chamber and inspected it. I found that the strainer was full of rust powder and dust. The carburetor was lightly disassembled and cleaned for quick maintenance right after returning home. I had also blown the air around the fuel cock, so I was sure that the accumulated dust was from inside the tank.
When you find such a problem, you can't overlook it. I used a pump to drain the fuel from the tank, removed the seat, pulled out both fuel tubes from the fuel cock fittings, and inserted a stopper plug into the fuel tube to prevent fuel leakage. Then I removed the tank to pull it out from inside the frame.
Let's practice the work of removing rust from the inside of the fuel tank. While holding the removed tank in my hand, I casually saw the CV Junior made by Kerbeck. It is an excellent high-temperature dryer that can control the temperature from about 50 degrees Celsius to more than 200 degrees Celsius and has a timer for one hour. It was already a best-selling product known to many Sunday mechanics as a heat application tool for drying paint and various maintenance. When I opened the glass door of that CV Junior and put in the passport tank, what a surprise! The door will close! I immediately started working on removing the rust while using the heat.
The chemical we used here was Hanasaka G Tank Cleaner. It's a great product that is neutral but has a great ability to treat that. Passport's tank is only lightly rusted, so I used 20 times dilution this time. Even if the tank is badly rusted, a 10x dilution will give a high level of treatment performance, so it is very cost-effective. This tank cleaner is characterized by the fact that the activity of the treatment solution is increased by heating it up, which results in high treatment performance.
If it's a large model tank, you'll need to break up the tank cleaner with hot water from the water heater and then fill the tank to the cap opening. To keep the liquid warm, we wrap the tank in several blankets, and some of our motorcycle friends put the tank in a large Styrofoam box given to them by a fish shop and wait for the tank to heat up, but the important thing is to keep the temperature of the liquid as low as possible during the operation. Incidentally, the fuel tank of the old Super Cub can fit in the CV Junior in many sizes, so the work progress is even easier. It's nice to have tools, isn't it?
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