The model with a 2-stroke engine is suitable for being called an endangered species. Even models with high-performance water-cooled engines leave a lot of carbon sludge in the exhaust system expansion chamber and in the expansion chamber. This was the case even with the latest (but still late 20th century) models, so many older 2-stroke models still have a lot of residue in the exhaust system. In this article, I will show you how to maintain the exhaust system of a 2-stroke engine at your own risk!
You could burn it on a propane burner.
I burned the exhaust pipe and the body of the exhaust system for the old 2-stroke model using a propane burner (it used to be used for wild firing in the past, but it is prohibited now. The propane burner is also used for making hand-bent exhaust system), I burned the exhaust pipe and the exhaust system body of an old 2-stroke model motorcycle. At the beginning of burning, the unburned engine oil was burned vigorously, but after that, it seemed to burn slowly. Since this kind of work can cause fire, it is important to ensure safety. This is especially true in the dry winter months.
Let's tap the cinders to get them out.
When you are sure that the fire is burned out to some extent (when the fire is extinguished), you should tap the exhaust system and exhaust pipe end lightly with a knocking hammer. It is better to prepare a wooden hammer or a piece of wood to proceed with the work, because the mouthpiece will be deformed if you hit it with an iron hammer or hit the exhaust pipe on the ground.
When unburned gas fumes continue to be emitted
If the carbon inside the exhaust pipe is not completely burnt off, smoke will be coming out of the exhaust pipe. This is a sign that the inside of the exhaust system or exhaust pipe has run out of oxygen. If you use an air gun to blow air into the exhaust system or exhaust pipe, it will often start to burn again. By repeating this process over and over again, you can completely burn off the dirt inside the exhaust pipe and exhaust system.
From pitch black sticky to metal ground!
As you can see, the inside of the exhaust spewed fire so fiercely that the metal surface became visible. This time we used a propane burner to burn off the carbon, but even a handy outdoor burner has more than enough heat to burn off the residual carbon.
The exhaust system that was burned with carbon here is an air-cooled 2-stroke engine model from the 60s. Whether painting or re-chroming, they would not undertake the work if the inside was stained black with carbon, and it would be a clear breach of etiquette if they did so. Since this exhaust system was to be re-chromed, it had to be cleaned more thoroughly. If the exhaust system is left dirty, it will contaminate the plating solution and that is a no-no. Also, in many cases, they will not undertake a exhaust system that has many internal bulkheads that make it difficult for the plating solution to escape.
Incinerators and wood burning stoves are available.
This exhaust system is an older design with the baffle pulled out to reveal a tube inside, so re-chroming is an easy specification to undertake. The dirt on the baffle that was pulled out was roughly burned off with a propane burner, but by throwing it into an incinerator or using a wood stove, the carbon can be burned off even more cleanly. Finally, let's use an air blow to completely remove the dirt.
- Point 1: The residual carbon that clogs the exhaust system of a 2-stroke engine cannot demonstrate its original engine performance unless it is removed thoroughly.
- Point 2: Residual carbon can be burned off with a burner flame, but depending on the situation, soaking in a degreasing cleaning chemical carbon cleaner can also be used.
The characteristic of the 2-stroke engine is that it explodes and burns a mixture of gasoline and air, which is a mixture of gasoline and 2-stroke oil. The 4-stroke engine explodes and combusts a mixture of gasoline and air, and this is the major difference between the two. The 2-stroke engine uses engine oil mixed with gasoline to lubricate the crank bearings, cylinder, and piston rings. On the other hand, engine oil is burned along with gasoline, so the exhaust gas emits smoke and has a distinctive oil-burning smell.
In the middle of the 60's, after the development of automatic lubricating devices (oil pumps) that fed engine oil according to engine speed and throttle opening (Yamaha's Auto Lube and Suzuki's CCI), it became possible to automatically mix the right amount of engine oil. Before that, however, it was possible to buy "mixed gasoline" at gas stations. Before this, however, it was possible to buy "mixed gasoline" at gas stations. There were also cases where riders prepared their own engine oil of choice and calculated the amount of oil to mix when refueling. In the world of motocross, where the throttle is opened and closed a lot and full-throttle driving is not always possible, the amount of oil mixed is reduced as much as possible to improve throttle response and extract more power. Even in the 1990s and later, when riding on the street, Italian Vespas and two-stroke engine farm machines use a gasoline mixture. When refueling with gasoline, the Vespa also had an oil measuring cup as standard equipment when the seat was opened.
In this case, we used a burner to burn off the residual carbon inside the exhaust system, but if it is not too dirty, or if there are no walls inside like a racing chamber, you can soak the exhaust system parts in hot water and clean them. If you have a straight design exhaust system silencer where the exhaust pipe and exhaust system body can be separated, you can prepare a thick PVC pipe, put the exhaust system in it, and pour hot water carbon cleaner on top of the exhaust system to remove the gooey carbon stains. It is recommended to leave the exhaust system in the cleaning solution for several days, but it is also effective to pull up the exhaust system and shake the inside of the exhaust system at least once a day.
The cleaning method varies depending on the condition and shape of the exhaust system, but if the exhaust system is still clogged with dirt, it will definitely not perform to its full potential. If your exhaust system sound is not bouncy and muffled, it's time to try exhaust system cleaning. In this case, we tried to burn the exhaust system in our own workshop, but it should be noted that chemical cleaning may be safer.
Re-chroming after burning off residual carbon
The two 2-stroke mixed gasoline engine models shown here. On the left is a Kawasaki 125B8 Fukushima Prefecture limited edition fruit color model, 1963 model. On the right is a Yamaha 125YA5 Deluxe, 1962 model. In both cases, the residual carbon inside the old exhaust system was burned off with a propane gas burner, cleaned inside, and then re-chromed. As you can see, the work was completed with a beautiful finish. You can never enjoy this kind of motorcycle without "Full Restoration".
