Next up in our series of features on motorcycle maintenance is a less talked about though equally important subject: oil change for your fork. For starters, let me ask you this: how many of you have changed the oil of their motorcycle's fork at the right time?
As you probably know, the lifecycle of a fork depends on how you maintain it, what the road conditions are, how efficient your brakes are and, most importantly, how your motorcycle handles on the road.
Depending on the type of fork featured on your bike, you have to use a specific hydraulic fluid with the appropriate viscosity. There are many types, blends and grades on the market, and each one will only prove effective if you stick to the manufacturer's recommendations, which take into account loads and riding styles.
Fork oil is quite akin to an automatic transmission's. It must meet specific criterions based on specific limitations, such as fighting friction, corrosion, emulsion and foaming. Bumpy roads lead to excessive action of the tubes and stanchions. The non-stop up-and-down movement of the suspension components creates friction and heat.
Oil decays over time, losing most of its initial properties and therefore its ability to prevent the fork's internal parts from wearing out. The easy solution is to periodically change the oil by referring to the schedule in your owner's manual. However, only skilled mechanics or seasoned riders with the appropriate tools should perform this type of work.
There are two categories of forks: conventional and inverted. The former is pretty self-explanatory, while the latter, also called "upside-down" fork, places the stanchions next to the wheel center. Why the difference? To enjoy a more effective weight transfer to the ground that factors in the type of motorcycle you're riding. For instance, a cruiser or a touring motorcycle will use a standard fork, while most sportbikes are equipped with inverted forks. One could argue that the market dictates which type of fork manufacturers will rely on for each of their models.