How to Change Fork Oil – Full Guide

how to change fork oil

When did you last change your fork oil?

Most riders don't consider changing their bikes' fork oil, and to be candid, bad fork oil might not cause significant danger to your motorcycle. However, it will make the fork stiff and move up and down a little slower.

If the fork in your bike has terrible oil, its spring will not allow the fork leg to compress on a bump and bounce back. This may result in diminished ride quality and premature bushing wear. So, you better change the fork oil once or twice a year at least.

How Does Fork Oil Work?

Quickly, let us understand how motorcycle fork works and its relationship with the oil. There are two main components of a motorcycle fork; this includes; the fork oil and spring. Fork oil provides both rebound and compression damping, which is the viscosity and quantity of oil. 

Motorcycle fork oil helps to determine the rate of rebound and compression. This means that the fork depresses speed on hitting a pothole, and the fork oil decides the speed at which it rebounds. 

The primary function of the fork oil is not lubrication, but damping. However, the oil helps to lubricate some of the internal moving parts of the fork. It would be best if you did not determine the fork oil Grade by its lubricating property. Instead, take into consideration its damping property. 

Some people might think fork oil is the same as engine oil, that’s not true. The engine oil is three times thicker than the fork oil and also have different primary functions. If you are interested about lowering springs then you can visit this page.

How Long Does Fork Oil Last?

Since the fork oil gets dirty and loses lubricity with time, you should change it every 10,000 miles or just twice in a year. Although this solely depends on the maker and model of your bike.  Some bikes fork oil may be changed within the first 5000 miles and so on. 

Tools Required for Fork Oil Change

Let’s look into some tools required for changing fork oil in a motorcycle: 

  • Jack or Triple tree stand
  • Torque wrench
  • Measuring jug
  • Replacement fork oil
  • 48mm fork seal driver
  • Fork oil measuring tool
  • 47mm fork seal bullet
  • Seal and O-ring grease

How to Change Fork Oil – Step by Step

Changing the oil on a set of traditional forks can be done quickly and easily, with no special tools or technical skills. 

However, the USD forks are a bit difficult. These may require special tools like a spin spanner and maybe spring compressor to remove the top plug depending on the model and manufacturer. Make use of your owner’s manual for the specific tools needed for your motorcycle model.

Follow the steps below to change your bike’s fork oil without any special tools or technical skills:

Step 1 - Lift the Front Wheel

Lift the front wheel of the bike from the ground using a back stand and a jack under the engine. Expel the front wheel, calipers, bumper, and some other parts attached to the fork legs.

Step 2 - Measure the Height of the Fork

It is vital that you measure the fork height and also note the exact spring preload setting. This is because your forks position on the triple tree decides the front-end geometry of the motorcycle. 

If you do not measure the fork height and the exact spring preload setting, in the end, your bike's handling might get imbalanced when you reinstall it.

Step 3 - Remove the Fork Cap and Plug

You might face a little challenge here. Depending on your motorcycle, the forks will either have a cap or a plug that sits on top. In either case, before you remove pinch bolts in the fork top, please make sure you crack off the fork legs top plugs. This will make it easier to take the fork legs out. 

Then remove the pinch bolts and release the fork legs by gradually sliding them out. You have to be very careful not to drop the fork legs, and they are fragile.

Step 4 - Remove the Internals

After you've unbolted the fork cap, remove the top plug gently – because there might be some fragile spring tension in there that you need to release. Once you’ve removed the plug, take out any washers and spacers. Be mindful so as not to lose anything. Put them into separation for cleaning. 

Now, gradually lift out the fork spring. Let the oil out into a graduated receptacle, pump the fork leg continually to remove all the old oil before taking it directly out.

Step 5 - Do Some Preliminary Cleaning

Indeed, some oil will be left inside the fork after pouring it out. To get it all wiped out, you need to spray degreaser inside the fork. Double check if the degreaser touches the outer and inner fork. 

This is done by pumping the forks in an up and down manner. Then, for some minutes before washing with pure water, leave the degreaser inside. 

Step 6 - Reinstall the Damping Rod

To make it hermetically sealed, you have to add string lock to the bolt that holds the damping rod together and screw it back in. This process is almost the same as while removing the damping rods. Pack the fork with the spring, hold the damping rod in place to keep it from pivoting.

Step 7 - Replace the Oil

Now that the fork is clean inside out, it’s time to pour the new oil. Note that you have used a graduated measuring cylinder to measure the amount of oil poured out. Next, top off your fork receptacle with the specific amount, grade, and weight of new oil; at that point, empty that into the fork. 

Pump the fork leg a few times to remove air bubbles from the damping system.

Step 8 - Check the Height of the Oil

To do this, make use of the service manual. It will give you an appropriate oil height level inside the fork leg.

Step 9 - Reassemble the Forks and Other Components 

Make sure the forks are arranged up through the triple tree. Also, tighten the bolts on the triple tree with your hand. Gently put in the springs, spacers, and washers followed by the fork caps. 

You'll have to reassemble the clip holding the plug/cap in place. The good thing about this process is that placing the cap in is better than removing it. After this, you can now replace the front wheel. If you want to know about mazda 3 battery then you read this article.

Final Words

After following these simple steps, we hope you now know how to change fork oil. Please note that before you start work, you need to make use of the owner’s manual to ensure the type and viscosity of oil recommended. Plus, the quantity of the right fork oil required for the service. 

Motorcycle Fork oil has its special primary function, never should engine oil be substituted for fork oil. Fork oil is readily available in motorcycle shops and some other mechanic shops.

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