Leaking motorcycle forks is a common occurence, especially if you ride on dirt roads. It is best to fix the leaking fork seals as soon as possible.
It is dangerous to ride a motorcycle with leaking fork seals. Fork oil can leak onto your front brakes, severly reducing stopping power. Forks without oil won’t rebound properly which may result in a loss of front wheel traction. If you have to ride home without fork oil, ride slowly, and use engine braking and the rear brakes.
So while the short (and mostly correct) answer is “No, you should not ride your bike with leaking fork seals“, it also depends.
Let’s say you are in the middle of nowhere and you don’t have food and water with you. You stop for a break and notice some oil leaking down your forks. Do you leave your bike next to the road and walk back to civilization, or do you ride home carefully?
Is it safe to ride with leaking fork seals?
While your bike won’t fall apart and it will be ridable with leaking fork seals, it is generally a bad idea.
Fork oil on your brakes is dangerous
The most obvious danger is leaking fork oil onto your front brakes. The front brakes are responsible for around 80% of your motorcycle’s stopping power. Lubing the rotors, calipers and brake pads with fork oil will result in roughly 0% braking power from the front end.
Next time you need to suddently slow down or come to a stop, your slipperly front brakes will mean diddly squat while your rear end will start to skid as your rear wheel locks up. I don’t think it is necessary to explain this any further.
If, however, your life depends on you keeping on riding the bike with leaky forks, just take into account that you’ve potentially only got 20% of the stopping power left and that you’ll need to rely on engine braking and feathering the rear brakes. It is totally possible to ride like this, but you’ll need to plan ahead and keep a longer following distance between you and the truck in front of you.
Oh, and you’re probably going to have to replace the front brake pads. Soaking them with oil will render them totally useless!
Forks need fork oil to work properly
The purpose of fork oil is not only to lubricate the moving parts, but to assist with dampening and rebound. The oil works together with the valves in your forks to slow down the movement of the forks after the springs have compressed. Without fork oil, your front end with feel like you are riding a pogo stick.
This may not be a huge problem if you ride very slowly and over even terrain, just to get home. But I would not ride like this in traffic or over rough terrain at high speed. If only one fork leg is leaking, the suspension geometry will be totally out. One side of the fork will rebound faster than the other, causing steering issues.
Rebound, or the rate at which the forks come back up after the springs were compressed, is controlled by the fork oil passing through valves in the tubes. Without any oil, the wheel will jump back up quickly and may even leave the ground for a moment. This will result in a lost of traction which could cause poor handling and deduced stopping power.
In short, riding without fork oil is not safe and should only ever be considered (temporarily) if you don’t have any other options.
Why do my motorcycle forks leak oil?
The most common cause for motorcycle forks to leak oil is dirt trapped between the fork seals and the inner tube. This allows oil to seap past the seals. Worn or damaged fork seals will start to leak and scratches on the inner tubes will also result in oil leaks.
Too much oil or air pressure inside the forks may push out the oil seals resulting in massive oil leaks. For a detailed post on why fork seals leak and what you can do to fix it, check out this post I wrote.
How do I fix leaks in my forks?
The first thing you can try is to use a cheap Seal Mate off Amazon and try to clean the fork seals. If your seals are worn, you’ll need to replace them. Inspect the inner fork tubes for damage and rust spots. If they are not 100% smooth, the seals will likely leak.
Finally, if your forks have too much oil in them, drain the excess oil to release the pressure. Forks with air valves on the top caps need to be bled (to atmospheric pressure) from time to time. I go into detail on each of these fixes in this post.
Conclusion
If your motorcycle’s fork seals start leaking it is best not to ride the bike until the cause has been addressed and the seals replaced. Fork oil leaking onto your front brake may severaly reduce stopping power and forks without oil will cause your front suspension to bounce around and behave like rubbish.
In short, it can be dangerous to ride a bike with leaky fork seals… but if you really have to, take it easy!
Ride safe!
Francois
