'How to' guides

WARNING: Using the wrong grade or wrong amount of fork oil can compromise your bike's handling and make it potentially unsafe. Refer to your manual or seek expert advice if unsure.

Unless you are a competent mechanic it is not recommended that you change your fork oil in any way. Because of this we have not included a step by step guide but instead an overview of fork oil.

Oil is used in motorcycle forks not just to lubricate moving parts, but just as importantly to provide 'damping'.

This in conjunction with the forks springs dictates the rate at which the forks compress and extend, smoothing the ride.

There is a network of valves and orifices inside your forks legs through which the fork oil is forced as the bike travels up and down on the front suspension.

Fork oil comes in different viscosities. Far lighter than engine oil, it’s important to use the correct grade and amount for your bike. For some specialist applications such as racing it is common practice to experiment with different grades and amounts.

a) Fork oil top up

A top up may be required if you want to match the damping to your riding needs and weight. Consult with a suspension or model expert before attempting this.

The only other reason you would want to top up is if there is any leakage, but if this is excessive, you will need to replace, or have replaced your fork seals. Consult your manual to see if this is a task you can accomplish.

This photo shows a syringe being used to top up the fork oil to a precise voume.

b) Changing the fork oil in basic forks

Some more basic forks have drain plugs at the bottom of the legs. If yours are of this type there is not need to remove the legs to change the oil. Once the oil is drained the level of new oil must be carefully measured to make sure the correct amount has been used.

c) Changing the fork oil in more sophisticated forks

More sophisticated forks require the legs to be removed. Generally it's easier to loosen the forks' top caps while the legs are still in the bike. The amount of oil must be carefully measured out (a large syringe is useful for this).

The mechanic will use a small steel rule or vernier caliper to check that the distance between the top of the oil and the top of the leg are as specified in your bike’s manual or to your particular requirements for revised damping.