There are secondary transmission systems like the shaft and the timing belt, although the most prevalent system is the chain drive which, depending on each bike's performance, may be various sizes or strengths.
Maintenance should be performed on the transmission chain every 500 km, but this number may vary depending on the driving style and if the chain is exposed to humid, dusty, or muddy environments. Obviously, aggressive driving can directly affect proper tension in the chain and will require more frequent adjustments. In addition, riding on rainy days can dry out the chain and dirty it more than usual, requiring us to clean and lubricate it more diligently. Dust and mud can also be harmful to the chain and is more likely to stick to the chain's lubricant, which is why we must stay on top of cleanings if we often ride the bike in dusty or muddy environments.
That being said, the frequency for cleaning and lubricating the chain will depend on those factors. Proper tension of the chain should be reviewed every time we perform any maintenance. It is unlikely we will need to adjust the tension each time we clean and grease, but we should always check to make sure it's correct.
Not performing necessary maintenance on a transmission chain may directly affect proper functioning of the clutch and gearbox, and may also affect the reaction time to the accelerator, causing crackling sounds, especially when accelerating with the engine at a low RPM. A loose chain can also affect driving safety, as it could possibly slip out of place and even break, causing an unintended and dangerous locking up of the rear wheel. This could also end up breaking the crankcase, which would be a costly and difficult repair. A transmission chain in good working condition means less power loss due to friction and lower noise levels in this part of the motorcycle.
How to maintain a chain with seals
In cases where the chain has seals, as is the case with most displacement bikes greater than 125 c.c., normal maintenance can be performed every 800 km or even less frequently. Sealed chains are more durable because they conserve the lubricant better and to a large extent prevent moisture and dirt from getting in between the links and their pins.
When adjusting the chain, we should be extra cautious because too much tension can cause quicker wear on the front and rear sprockets and even damage the bearing and/or the seal on the outside of the secondary shaft of the gear.
How to clean the chain
In order to clean the chain, a specific degreaser should be used along with a brush that isn't too stiff. Finish off the job with cellulose paper or a cloth. If it's really dirty, we can use pressurized hot water or diesel, but be careful not to overdo it with these cleaning methods. If the chain is very dirty and has a master link, which is quite common nowadays, we can open it and remove the chain for a more convenient cleaning.
How to grease the chain
Once it is clean and dry, we can grease it. If the bike has a center stand, this task will be much easier. Put the bike on its center stand, start the engine, place it in first gear, and turn the rear wheel with the engine idling. If we don't have a center stand, we can use a paddock stand. We can also grease it with the help of the side stand, but because we can't turn the rear wheel in first with this stand, we have to move the wheel in neutral. In this case, it might be a good idea to get help from another person. In order to keep the chains and secondary transmissions in perfect working condition, try the Moto Chain aerosol-format lubricating oil.
Another recommendation is to not use the bike immediately after greasing the chain. It's best to let it rest for at least two or three hours so that the product gets deep into the chain and the solvents evaporate. This will also prevent a great deal of the product from splashing and dirtying other components on the bike.
When greasing the chain, we must be careful not to get lubricant on the rear tire or any other parts of the bike. To prevent this from happening, we can place a piece of cardboard behind the chain and in the path of the spray nozzle.
How to adjust the chain
There are different systems for adjusting chain tension, although the most common are the axle nut and lock nut system and the eccentric chain tensioner when it comes to double-sided swingarms. Before making any adjustments, we must loosen the axle nut on the rear axle and remember to tighten it after adjusting the chain. There is no need to over-tighten it because it may cause damage to the bearings on the rear wheel. It's best to use a torque wrench and follow the manufacturer's recommended tolerances.
When adjusting the chain, we should keep in mind the existing marks on both sides of the swingarm and put them back evenly so that the wheel isn't lopsided and the transmission functions correctly. With the axle tightened and the bike on the ground, we should put some weight on the seat and check that the chain hasn't been overtightened. It's also a good idea to leave a little more slack than normal if we're going to ride the bike with a passenger or baggage.
When the chain has reached the end of its useful life, it's recommended to replace the complete transmission kit made up of the chain and front and rear sprockets. If we only replace the chain, and the front and rear sprockets have some wear and tear, the new chain will have a much shorter life span.