Modifying a motorcycle is one of the more enjoyable parts of owning a two-wheeled machine. From choosing a different set of tires to fine tuning ergonomics, motorcycle modification can be a fun and educational experience for the rider. One such component which is often overlooked when it comes to simple tuning and modification is the suspension. Fine-tuning the way a suspension carries the motorcycle and rider can drastically change the way a motorcycle performs on straight roads and twisty corners alike. If you’re looking to change the way your motorcycle handles, here are 4 simple suspension modifications for your motorcycle.
Adjust fork height
Fork height adjustments can be made by loosening the triple tree clamps and allowing the forks to slide up and down. Lowering the front (or decreasing the distance between the wheel and the triple tree) can provide a sharper turn in and cornering feel to the motorcycle but will conversely be less stable when going at higher speeds. The opposite effect is true when the front is raised—turn in and cornering may feel a little less sharp but high speed stability may be gained. A motorcycle is generally tuned from the factory for neutral handling, and fork height adjustments are typically kept in the +/- 3mm range since too much adjustment may be detrimental to the handling of your motorcycle. It is important to consult your service manual or the service center in order to know the exact tolerances of your motorcycle for this modification.
Tuning fork oil
Fork oil is also one of the easier mods to tune on your suspension. This can primarily be tuned in two ways. The first is by changing the fork oil entirely to a different weight—typically a heavier or lighter oil, and can be done by disassembling the fork, replacing the fork oil, and reassembling the assembly. A heavier fork oil weight will stiffen up the compression dampening and will also slow down the rebound dampening, while a lighter fork oil does exactly the opposite. In general, heavier fork oils are typically used for more aggressive riding while lighter fork oils are used for non-aggressive riding.
The second way fork oil can be used to tune your suspension is through fork oil quantity. On a fork tube, a mix of fork oil and pockets of air can be found inside. By increasing the quantity of your fork oil by a few milliliters, you are reducing the amount of compressible air. Increasing fork oil volume will stiffen up the forks from the mid stroke until the forks bottom out, while decreasing fork oil volume will do the opposite. Fork oil volume tuning is best utilized when attempting to finetune the suspension’s travel and stiffness at different points of the suspension stroke.
It’s important to note, however, that the tuning of fork oil weight and quantity is a very technical job to execute properly and is best done by an expert mechanic or your dealership’s service center in order to provide best results. The exact weight and quantity to be used highly depends on riding style, riding terrain, road conditions, and the motorcycle’s factory tuning. As such, make sure to consult reputable mechanics or your service center in order to tune for best results.
On some motorcycles, suspension components can be adjusted for preload which is meant to be adjusted for sag. While the dynamics around suspension sag is a bit of a technical topic to delve into, all you should know is that preload is set based on the rider’s weight, accessory luggage weight, and the weight of a pillion rider if included. Preload is not meant to be adjusted many times over—it’s meant to be set once and must only be adjusted if the rider weight or luggage weight changes, or if there is a presence of a pillion rider. By setting your preload to the correct setting for the weight on top of the saddle, you’re ensuring that your motorcycle can perform optimally across the broad range of road conditions and riding styles it was designed for.
The last modification that can be done to your motorcycle would be to swap out components completely for professionally engineered third-party suspension components. The Royal Enfield Himalayan, for example, has aftermarket support where the internal components of the front forks and the entire rear shock can be replaced with the expertly designed and adventure-oriented components from the suspension gurus at Öhlins. Aftermarket parts for your suspension are typically designed for a specific performance objective or a specific riding feel.
If you’re going down this route, expect to spend a few tens of thousands of pesos for these components, but also know that you are definitely getting your money’s worth as these parts go through extensive testing and engineering in order to elevate suspension performance without all the trial and error from DIY tuning. Simply swap the part, apply your desired settings, and you’re good to ride with top-notch suspension components.