When it comes to refilling the forks of a motorcycle, it's important to follow the manufacturer's recommended procedure and specifications. While it may seem logical to empty the forks, bottom them out, and then fill them to the top of the tube, there are a few reasons why this may not be the recommended method:
Air Trapped in the Forks: By bottoming out the forks, you may trap air within the fork tubes, which can affect the performance and consistency of the suspension. Air bubbles can compress and cause inconsistent damping, leading to a less predictable and potentially unsafe ride.
Suspension Tuning: The amount of oil and its level in the fork tubes directly affects the suspension's behavior and performance. Manufacturers provide specific recommendations for the correct oil volume and level to achieve optimal damping characteristics and handling. Deviating from these specifications can result in an imbalanced suspension, affecting stability, comfort, and control.
Hydraulic Lock: Overfilling the fork tubes can lead to hydraulic lock, where the excess oil fills the air space, reducing the available space for the forks to compress. This can result in a harsh ride, limited suspension travel, and potentially damaging the fork seals or internals.
To ensure the best performance and safety, it's advisable to consult the motorcycle's owner manual or contact the manufacturer or a professional motorcycle technician for guidance on the correct procedure and specifications for refilling the forks of your specific motorcycle model.