Non-Seal Chain for Discontinued Small-Displacement Motorcycles that can be Washed Entirely with Oil Wash

In contrast to the seal chain, which is the mainstream for current mid-size and larger models, the non-seal chain was the standard for out-of-print vehicles prior to the 1970s and is still popular today, especially in the moped class.
However, because there is no rubber seal, there is more freedom in selecting a cleaner for cleaning, and depending on the degree of dirtiness, it may be possible to soak the chain in cleaning oil.

Regular lubrication is essential for non-seal chains where pins and bushings are in direct contact

Non-seal chains are common on current models in the moped and moped 2 classes.
Because no O-rings are inserted between the link plates, the chain can turn for a longer period of time than a sealed chain when the rear tire is idling. However, when the riding force is applied by the engine, friction loss tends to increase because there is no grease to keep the link pins and bushings lubricated. To avoid this, regular chain maintenance is essential.

Most non-seal type 420 chains are clip-jointed, and the clips can be easily attached and detached with pliers or other tools. Therefore, if the chain is noticeably dirty, it can be removed from the vehicle and cleaned by itself.
When installing the clip, the U-shaped closed side should face the direction of travel.

Comparing sealed and non-sealed chains, it is clear that sealed chains have an advantage in terms of both friction loss reduction and longer life. Looking at the structure of the chain that transmits driving force, it is clear that the sealed chain has an advantage in terms of lubrication, as grease is sealed in the gap between the link pins and bushings that connect the frames, which are subject to large forces.

Seal chains became standard equipment on production vehicles in the mid-1970s, initially in the 630 sizes for large vehicles, and eventually in the 530, 520, and 428 sizes as well as in smaller sizes, expanding the range of applicable vehicles to the mid-size class.

Some say that the rubber seal inserted between the plates to prevent the grease sealed between the link pin and bushing from leaking out causes resistance, but this resistance is only felt when the chain is twisted by hand and is not enough to cause problems when the driving force of the engine is applied. Rather, it is more important that high-quality grease is sealed between the link pin and bushing, where lubrication is critical, and that it not be contaminated by gravel, dust, or debris, in order for the chain to maintain its performance for a long time.

On the flip side, non-seal chains, which are still often used in small-displacement vehicles, mainly in the moped class, are even more important to maintain than seal chains. This is because the link pins and bushings, which are the key to wear and life, are in direct contact with each other. This is the structure of the chain, to begin with, and even today, the non-seal type is common in industrial applications.

However, for drive chains for motorcycles, which rotate at high speeds and have large torque fluctuations, seal chains were developed for the purpose of reducing wear and friction loss. Therefore, even though the engine output, vehicle weight, and other loads are lighter than those of mid-size and larger models, if proper maintenance is not performed, the deterioration speed will inevitably be faster than that of seal chains.

When applying chain lubricant to a non-seal chain, it is easy to focus on the roller area where it contacts the sprocket teeth, but the most important thing is to allow the oil to penetrate the gap between the link pin and bushing. Although an oil film between the rollers and sprockets is necessary, the main cause of chain elongation is link pin wear, so the oil applied between the link pin and bushing from the mating surfaces of the plates is more important.

However, even after applying a special chain lubricant, the oil will eventually run off due to the centrifugal force applied to the rotating chain, so regular lubrication is essential. At the same time that oil disperses, dirt such as gravel and dust that adheres to the chain while it is operating may also enter the chain.

When these contaminants act like a file, they accelerate the wear of the link pins and bushings, resulting in progressive chain elongation. This means that not only must the chain lube be topped up, but also the underlying dirt must be thoroughly cleaned before lubrication.

Again, the seal chain remains best lubricated because grease is pressed into this area in advance and sealed with a rubber seal. Chain manufacturers recommend lubricating the seal chain between the plate and rubber seal or between the bushing and roller, not between the link pin and bushing.

Also, with regard to cleaning, the work is to wash away dirt adhering to the bushings and rollers or plates and rubber seals, and care must be taken not to use detergents or chemicals that may damage the rubber seals.

Non-seal chain that can be drastically cleaned without delicate rubber seals

Clean the chain in a metal container with a brush using kerosene or old gasoline as a substitute for washing oil.
If the chain is too dirty, the washed-out dirt may adhere to the chain again, so the washing oil should be changed during the process. In the case of a chain with sticking chain lube deposits and reluctant link movement, washing may allow the link to move smoothly, but this is due to the fact that the link pins and bushings are no longer completely lubricated, so do not mistake this for a reduction in friction loss.

The bottom of the container became coarse as grit and dirt that had penetrated each part of the chain seeped out.
Spray-type chain cleaners are effective in blowing off the details of dirt dissolved by the cleaning ingredients with gas pressure, but require patience and time to clean each link one by one. In contrast, soaking and washing have the advantage of efficient cleaning, although degreasing and drying are required after washing.

After cleaning, check that all links move smoothly. If they are partially sticking, the link pins and bushings may be seized or otherwise in trouble and need to be replaced. If the roller that engages the sprocket does not rotate due to rust or other problems, the chain should also be replaced. It is easier to check a chain by itself than when it is mounted on the chassis.

If cleaning fluid is left on the chain, the chain lube that has been applied may run off. Since it is difficult to remove cleaning fluid that has entered the gap between the link pin and bushing, spray chain lube after degreasing and drying with air blowers or parts cleaners. I recommend placing a piece of cardboard between the chain and the tire to prevent chain lube from sticking to the tire or wheel.

Chain lubricant should be sprayed not only on the rollers but also in the gap between the link plates so that it can spread between the link pins and bushings. Some chain lubes have a thicker film that offers good fixation, but when used on non-seal chains, good fixation and good penetration are also important, so read the product features carefully before making your choice.

Cleaning a non-seal chain does not require consideration of damage to the grease between the link pin and bushing or the rubber seal used to seal it. Therefore, cleaning can be practiced in a more drastic way than with sealed chains.
Using chain cleaner is the right choice, but with clip-joint type chains, which are common in the moped class, they can be removed from the vehicle body and soaked in washing oil.

When kerosene, which is often used as a washing oil, is put in a metal batting, the chain is soaked in it and rubbed with a brush, dirt between the bushings and rollers and between the link pins and bushings will flow out in an interesting manner. Spray-type parts cleaners also have the same effect, but in the case of oil wash, it is more effective for chains with chain lube stuck to them like clay because it can be soaked and worked on for a longer period of time. Incidentally, in the case of seal chains, the rubber seals may be swollen or damaged depending on the type of cleaning solution or chemical used, so a cleaner compatible with seal chains is essential and an oil wash should not be used.

If cleaning is encouraged before applying chain lube, dirt is unlikely to seep out when soaked in oil wash, but in the case of mopeds that have been skipping maintenance as described here, the oil wash may become cloudy and dirt that has been embedded in details may flow out at a greater rate than expected. If you feel a rough touch when turning the roller or a creaking sensation when bending the link, it is a good idea to perform a soaking wash.

However, when cleaning with an oil wash, the chain lubricant may dissolve and have difficulty settling, so the remaining oil wash inside the chain should be blown off with an air blower or degreased with parts cleaner before lubricating the chain anew. When doing so, it is also important to lubricate not only the rollers, which are easily visible but also the link pins and bushings, which are key to lubrication, by targeting the gap between the plates so that the oil can be spread to them.

A maintenance article in a motorcycle magazine from the 1960s described boiling a non-seal type chain in engine oil.
The aim may have been to increase the fluidity of the oil by raising its temperature and spreading it to various parts of the chain, but there is no difference in the fact that the oil would be dispersed by centrifugal force when the motorcycle is ridden. Compared to those days, today's chain lubricants have improved in all aspects of performance, including penetration, friction reduction, and fixation, thanks to a variety of additives.