At a time when motorcycles are fitted with sophisticated traction control systems, adjustable power modes, and ride-by-wire throttle systems, the ubiquitous drive chain seems almost rudimentary by comparison. After all these years, it still looks like an overgrown version of what we had on our bicycles growing up – but there’s much more to a contemporary motorcycle chain than you may think.
“Today’s chains must balance performance, durability, and weight depending on the riding discipline, displacement of the engine and the environment,” explained Farrah Bauer, Marketing Manager at RK Excel America. “For example, a supercross rider wants a balance of high performance and light weight, while the average motorcycle commuter prefers durability, longevity, and cost-effectiveness.”
Today’s street bike chains consist of inner/outer plates, pins, bushings, and seals, the latter of which is often the subject of debate when it comes to chain performance and longevity. Bauer weighed in, saying,
“One of the most common misconceptions about motorcycle chains is that non-sealed chains perform better than sealed chains. The reason for this misconception is when someone spins the tire of a sealed chain vs. the tire of a non-sealed chain, the non-sealed chain will easily spin, while the sealed chain doesn’t spin as freely. However, once the seals of the chain warm up, there is very little seal drag. For example, if you were to place non-sealed chain on a dyno and run it through a race scenario, you’d find that a non-sealed chain will create its own friction as the chain heats up and expands. This friction can reduce horsepower and performance. However, when a sealed chain is put through a similar scenario, the chain’s seals prevent heat expansion, reducing friction and keeping the horsepower delivery constant from the start of a race to the end. The seal rings also act as a dampener to hold the chain firmly, preventing the components from vibrating upon each other during riding. This assures a smooth power transmission from the engine to the wheel.”
Another area where the subject of seals comes into play is lubrication. Because street bike motorcycle chains are internally lubricated, there is often some confusion among enthusiasts as to how often a chain should be cleaned and lubricated, if at all. Bauer explains,
“The purpose of lubricating a chain is to keep the chain seals pliable so that they can keep the internal lube in and dirt and debris out. If the seals are allowed to dry out or get damaged, the internal lubricant can either escape, or get contaminated, and the wear life of the chain can be greatly reduced. In order to get the most value for your money, you should clean and lube your street bike chain every 200 miles for non-sealed chains and 300 miles for sealed chains. You should clean and lube a dirt bike chain after every ride. You can also void the chain’s warranty by not cleaning and lubricating or maintaining the chain properly.”
Never clean a chain using brake cleaner or other caustic chemicals, and RK Chain in particular advises against using a certain common household lubricant in a blue and yellow can. Experts point out, that “As the product dries, it changes the molecular structure of the nitrile butadiene seals and can damage the material, decreasing wear life.” Instead, the manufacturer recommends the use of an O-ring safe cleaner and a soft rag; it does not recommend the use of wire or coarse plastic brushes, which can damage seals. “Spray the chain, and then using the rag, wipe the chain to remove dirt and debris,” Bauer instructs. “Once the chain is clean, we recommend riding the bike around the block to warm up the chain and remove any residual cleaner. After that, and while the chain is still warm, lube the chain with a product that is safe for use on sealed chains, then use a soft rag to remove any excess lube.”
In addition to proper cleaning and lubrication, correct adjustment is also an important part of chain maintenance. “An over-tensioned chain will cause excess force to be applied to the chain when the suspension is at the bottom of its travel,” said Bauer. “If the force is sufficient, it can bend or deform the pins. On the other hand, too much slack can cause the chain to jump off the sprocket.” The basic concept is that, when the chain is correctly adjusted, there should be some slack in the chain – but Bauer says RK recommends that you consult your motorcycle owner’s manual for chain slack recommendations.
As the miles add up, check the chain for signs of excessive wear or damage. Common concerns include rust, kinks and what is known as “chain float,” where the chain can be pulled away from the rear sprocket–a sure sign of chain elongation. Cracks, missing/damaged parts, wear marks on the top or bottom of the chain, or pin rotation are also signs the chain should be replaced. “In most quad-staked chains, the pins will all be in alignment from the factory,” said Bauer. “However, as the chain ages, the internal components can start to wear down, which can allow for pin rotation (where the pins turn a different direction).”
When chain replacement is indeed necessary, the front and rear sprockets should be replaced as well. “Failure to change the sprockets when you change the chain can void the chain’s warranty. Depending on how worn the sprockets are, a new chain might not even fit on a worn sprocket.” Even if it does, the excessive or irregular wear on the sprockets will certainly cause the new chain to wear out faster.
“Chains are not a glamorous product,” Bauer concedes. “They’re dirty and greasy, but are an integral part of the motorcycle. With proper installation and maintenance, a chain can last many years and thousands of miles.”