KKE Fork Service: Seal Replacement and Oil Change for Sur-Ron and Arctic Leopard XE Pro

If you are seeing an oily film creeping down the lower leg of your KKE suspension fork, or the fork feels like it is losing its damping and shedding oil, the seals on the damper side have most likely worn out. It is a common service item, and it is the same job on the Sur-Ron and on the Arctic Leopard XE Pro because they share the KKE fork. This guide walks through what is happening inside, how the seal and oil service works, and how you can tune the oil to suit your weight. It is an involved job, so read the safety note first and be honest with yourself about the tools and time it takes.

Which side leaks, and why

The KKE fork has two legs. Only the damper side holds oil, so that is the side that leaks and the side this service is about. The spring side uses the same dust wiper but has no oil in it, so it does not leak. Inside the damper leg, oil is sealed in by an oil seal and kept clean by a dust wiper. Over time that oil seal wears and lets oil weep past it, which is the film you see on the lower leg. There is also a small air piston deep in the damper cartridge with its own seal. That seal can leak too, and the plastic air piston itself can crack or bend, which lets oil slip past into the air chamber and pushes oil out of the bottom. Cleaning it up means new seals and fresh oil.

Tools and parts you will want

Have these ready before you start: a set of small Allen keys, a 32mm socket for the top cap (use a socket, not an open wrench, because the fork aluminum is soft and a wrench will chew it up), ideally an impact wrench, a gas torch to gently warm the caps that are sealed or thread-locked in place, fresh fork oil, and a fork seal and dust wiper kit. The KKE fork runs 35mm stanchions, and 35mm mountain-bike fork seal kits are commonly used here as a clean, high-quality option. Confirm the exact kit with us before you order so you get the right one.

How the seal and oil service works

This is the shape of the job on the damper leg once the fork leg is off the bike. Take your time on each step.

1. 1
   Open the top. Undo the small Allen screw and lift off the top cap. Watch for a small metal pin so it does not fall out.
2. 2
   Remove the 32mm top cap. Use the socket. If it is stuck, warm it gently with the torch and it will release. Do not use an open wrench, it will round off the soft alloy.
3. 3
   Compress the leg. Let the air out of the chamber first so the leg can fully compress, then push it down.
4. 4
   Undo the bottom damper bolt. An impact wrench makes this easy. Without one, you have to block the internal cartridge from spinning while you loosen the bolt, which is fiddly but doable.
5. 5
   Remove the damper cartridge and inspect the air piston. Draw the cartridge out, drain the old oil, and check the air piston and its seal. This is a common failure point. If the seal is worn or the piston is cracked or bent, replace it.
6. 6
   Replace the oil seal and dust wiper. Lever out the old oil seal and dust wiper and fit the new ones. Slide the inner tube back in.
7. 7
   Bleed and fill with fresh oil. Add oil and cycle the damper up and down until no more air bubbles come out, then top up to the correct level.
8. 8
   Reassemble carefully. Refit the cartridge and caps. A dab of thread locker helps, and remember the alloy is soft, so snug and secure, not gorilla-tight. Pump the air back in at the bottom when you are done.

Tuning the fork oil for your weight

The standard choice is a 5W fork oil, and any reputable brand of 5W is fine. Here is the useful part: you can tune the feel. A heavier rider, or anyone who wants firmer, more controlled damping, can step up to a heavier oil such as 7.5W. If you want a plusher, lighter feel, a lighter oil does the opposite. You can also adjust the oil volume slightly to change how progressive the fork feels near the end of its travel. If you are not sure what to run for your weight and riding, message us and we will point you to a good starting point.

Ride a KKE-equipped bike? Here are the two we sell it on.

Questions about seals, oil weight, or the service? Reach out to us. We are here seven days a week.