[DIY Small Classroom]Changing the chain is that simple!


From beginners to experienced knights, I believe that many knights have come into contact with small displacement cars. Unlike the CVT belt drive system of the Sudder models, most of the gear models use chains to transmit power to the rear wheels, such as NONKEY 50, NSR50/80, Super Cub, etc.

Since small-displacement cars have lower horsepower and lighter weight than large cars, they are often used as a means of transportation, and often neglect maintenance to put the car in harsh conditions, and for the most important chain of the transmission system , Although lubrication and cleaning can extend the life of the chain, it is also important to replace it in time.

Small exhaust vehicles often use oil-free chains and are easy to stretch

002-3▲When the chain is elongated and the gap increases due to long-term riding, it is necessary to loosen the rear wheel axle and adjust the chain adjuster to reset the chain tightness. When the chain adjuster is adjusted to the back, it means it is time to replace the chain, as the chain adjuster of the car model in the picture is almost adjusted to the back.

003-2▲Compared with oil-seal chains with rubber O-rings between the inner and outer chains, the oil-seal chain can move more smoothly and has less operating resistance. However, since the links of a chain without oil seal will directly contact during acceleration and deceleration, the power loss is greater than that of an oil seal chain.

Generally speaking, the chain size used in small displacement cars is mostly 420, and most of them are non-oil seal chains. Compared with an oil-seal chain with an oil seal between the chain and the roller, a non-oil-seal chain has less rubber O-rings that can retain lubricating oil, so there will always be direct contact and friction between the chain and the roller.

Since cars with small displacements are easier to ride and control than large cars, they are often used as transportation. Dirty water, mud, dust, dirt, etc. from the rain will quickly accumulate on the chain, and the body is light and has Enough horsepower output, so it is easy to frequently accelerate or decelerate suddenly.

The greater the acceleration and deceleration speed, the greater the force exerted on the chain. In this case, the friction between the chain and the roller will cause the contact surface to wear and cause the chain distance to expand and extend the chain. Of course, even a chain without oil seal can be ensured by the manufacturer’s quality control to ensure sufficient durability, but if the chain is not maintained and lubricated according to the time, the chain elongation speed will be faster than that of the chain under maintenance. Much faster.


Many small displacement cars use oil-seal chains
Chains without oil seals require more frequent oiling and maintenance than oil-seal chains

The allowable range is only 1%!Lengthening issues that need attention

004-2▲The top is the new chain, and the bottom is the old chain. As the gap between the chain and the roller increases after the old chain is used, the arc of the chain when picked up sideways will be larger and wider than the new chain. It will also be wider than the new chain.

The chain tightness will become loose as the chain becomes longer, so use the chain adjuster on the rear axle to adjust the chain tightness. It should be noted that the tension of the adjusted chain will return to the normal range at first glance, but the chain extension = chain length becomes longer, so when the chain is gradually elongated, the distance between the tooth root and the tooth root will gradually be different, and the tooth root will also It will become thinner and sharper, so although it will increase maintenance costs, it is still recommended to replace the chainring while replacing the chain.

Although the chain length can be known by adjusting the chain adjuster on the rocker arm, the chain length can be calculated more accurately by measuring the length between the bolt and the bolt. Taking the 420 chain as an example, the distance between the pins is about 4/8”=12.7mm, so the distance between 11 pins is 127mm.

According to the recommendation of ENUMA CHAIN ​​(EK chain), as the chain is elongated and the spacing between the pins increases to more than 1%, it is the time to replace the chain. In other words, it should be replaced when the pitch is increased from 127mm to 128.3mm. This sounds harsh, and when you consider that a chain is composed of more than 100 bolts, you will find that the 1% difference is quite huge.


The chain will gradually elongate due to wear
Even if the length of each chain is small, it still makes the length of the entire chain significantly longer
If the elongation is greater than 1%, the chain must be replaced

Oil-seal chain that can be installed without special tools

005-2▲The EK chain has 420 and 428 oil-seal chains and 420-size oil-seal chains. The 420-size oil-seal chain corresponds to exhausted vehicles of 80cc and below, while the 420SRX oil-seal chain using QX rings can correspond to up to 150cc cars. . This also means that an oil-sealed chain with a lubrication structure between the bolt and the chain can withstand higher horsepower loads.

When replacing the chain, the most important thing to pay attention to is the length. If the number of teeth of the front and rear chainrings are the original specifications, then you can directly refer to the recommended length of the maintenance manual. However, when the number of teeth of the current and rear chainrings increases or decreases, the chain The size will vary. This time, we will take the 1994 YAMAHA CHAPPY with the original gear ratio as an example to teach you how to replace the chain.

Since the length of the chain shown in the demonstration is longer than that required by the original manufacturer, you can cut off 6 chain items first, and then load the new chain into the car for a closer look. Remember to adjust the chain adjuster to the front in this step. After determining the length, you can safely use the chain driver to push out the excess pins to shorten the chain length.

Generally, the connection of oil-free chains has a U-shaped buckle, which can be fixed with fingers or needle-nose pliers, and can be easily completed without the use of special tools. However, when installing the U-shaped buckle, please note that the opening must face the opposite direction of the chain operation (when the opening is above the opening, the lower opening is forward), so as to prevent the U-shaped buckle from being loose due to foreign objects during riding.

After installing the chain, use the chain adjuster on the rocker arm to adjust its tightness to the correct degree. During adjustment, the rear wheel can be fixed in gear, so that the chain can be prevented from moving and easier to adjust.

Although oil-seal chains have lower operating resistance and are more suitable for small displacement cars, oil-seal chains require more careful and frequent maintenance than oil-seal chains, so please replace them when appropriate.

Change focus

006-1▲There are two ways to fix the front chainring, nut fixing and C-buckle fixing. As you can see in the photo, the C-shaped buckle is mostly used on cars with small displacement. If you find any deformation when you remove the buckle, please replace it with a new one.

007-2▲Adjust the chain adjuster to the front of the rocker arm, and then fix the chain on the chainring to determine the extra part that needs to be cut. If you find that the two ends cannot be joined at this time, you can try to adjust the position of the axle or one more chain eye .

008-1▲When cutting the chain, regardless of the size of the chain, both ends of the connection must be pressed tightly. It is recommended to use special chain tools during construction and remember to lubricate to prevent wear, because the chain driver is used to push out the latch. At the time, the chain driver will exert a lot of force on the bolt.

009-1▲The chain link is composed of inner chain pieces, bushings, outer chain pieces and U-shaped buckles. The lubricating oil of the oil-sealed chain will be sealed between the bushing and the chain pieces, so it can provide excellent lubrication performance, but no oil seal The chain does not have this design, so daily maintenance is very important.

010-1▲When the chain moves in the correct direction as shown in the photo, the opening of the U-shaped buckle must face the rear of the output force. When fixing, please clamp the outside of the U-shaped buckle with needle-nose pliers, and securely fix the U-shaped buckle on the pin . Here, a 0.4mm stainless steel wire is used to fix the outer chain piece and the U-shaped buckle, which can more effectively prevent the U-shaped buckle from accidentally falling off.


If you don’t know the exact length of the chain, please hang a new chain to confirm the length before cutting.
Please fix the opening of the U-shaped buckle backward.

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Information provided by “Webike magazine”
“Webike Taiwan” editorial department compiled

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