Leaking forks - Opportunity or Waste of money? (OEM vs others)

How many hours on the oil?

SKF seals are worth the money and offer some reduction in stiction. They also seem to last quite a bit longer.

The oil in the cartridge wears out first. What I am getting at is cleaning the seals if they only have 15 hours.

I would like to see them replaced. Make sure to check the bushing for hot spots.

SKF seals are more durable than stock KYB, but I really don’t think they have less friction. Those stock Yamaha seals move very freely compared to stock KTM (skf).

Can verify. They last magnitudes longer than OEM and other aftermarket stuff I've used.  Years instead of months.  I have to shorten/tighten the garter spring of the outer dust seal to get any kind of service life out of the non-skf stuff.

I've had pretty good luck popping the dust seal and then running a real thin piece of plastic around the inner seal and pulling out pieces of sand etc.  Can usually get some more time out of them this way before they start leaking again. 

I think someone even makes an actual tool to do it but I always just cut a plastic jug and make my own.

Motion Pro do one, used it on my Husky, definitely bought some time.

We use a .003" feeler gauge and it works perfectly.

We have areas that are red clay and when it gets hot and dried out the dust is ultra-fine, like talcum powder, and will bridge the seals in very little time. We pop the wiper down and work the gauge around at an angle to push the grit down and out and also clean the wiper since it had to get by there first. Works like a charm.

I've seen forks pouring oil like they had a seal come out because of that dust and after cleaning them with the feeler gauge they didn't leak another drop.

https://riskracing.com/products/seal-doctor_fixes_leaky_fork_seals

40 hours on original seals, etc? You are at least 10 hours past the recommended service interval(I go 30hrs max). Just get the OEM Yamaha seal kit which includes all the bushings and sliders. Its only about $50. While you're at it have the shock oil changed. Its time.

At 40 hours depending on your skill level its best to do seals and bushings. Skf does make a noticeable difference. Like someone posted here a coated lower tube vs non coated tube. I showed a buddy on fork with the kyb seals and bushings vs my same fork with skf and while not as drastic as the coating difference it was enough to get him to buy in on skf.

For oil if you wanna try something different you can try Smart performance spi oil its pretty good especially in kyb forks and shocks. But i would also change the cartridge oil at this point it has over 15 hours since you changed the outer at 15. 

As far as vaccume bleeding a shock. If you hand bleed it right you would be surprised how little if any air comes out. The DRC filler cups help alot. I wont say what shop I went to with a vacuum bleeder except for they are a major shop. I wanted to test what would come out after i hand bleed my shock. We both agreed the small amount of air would be insignificant to even a top level pro. Vacuum bleeding is just a lot faster. I take 20-30 minutes to bleed my shocks while im doing othere shit. If they do it its done in minutes. My ways still cheaper though. 

Everyone else has pretty much covered everything I have to say but I'll chip in anyway.

In my experience you can get another 5 or 6 rides out of a set of seals by cleaning them out but once they have started leaking they will need doing soon. 

I've tried a few different brands of fork seal, initially from sending them off and now from doing it myself. The SKF dual compound seals are incredible, I've got a set of cone valves so you don't need to replace the seals to disassemble and service the forks and I've got nearly 80 hours on one set of seals now. To me that's just insane and well worth the money

40 hours? You definitely need a full seal and oil service on both the forks and the shock.

Funny story. I bought one of these for my 2015 KX450 with the SFF Air forks. I didnt let the air out before using it. Guess who got splattered with oil gushing out when inserting this thing in the seal?

If you work the tool just right the pressure pushes the dirt out of the seal. 

Thanks for the levity on a Friday!

The stock SKF seals in my 2016 KTM finally started leaking in late 2020. Didn’t even try cleaning them, popped a new SKF set in and still leak free in 2024 with well over 100 hours on them. 

Stock Yamaha seals lasted ~20 hours. SKF went 75 hours and were still leak free when I changed them and the bushings with new oil. Old bushings didn't look too bad, but the oil I use is supposed to be good for 100+ hours. Been running it for 15 years and never had an issue. 

If you remove the seals they’re junk regardless of condition prior to. 
 

In my opinion, SKF is a good upgrade and not a huge difference from OE pricing in the grand scheme.

when I do seals, I typically do bushings as well since I’m in there.

Also, check your lower fork legs closely for nicks, etc. It takes very little to nick your new seals. If it’s a small raised edge you can use very fine (2000ish) wet/dry sandpaper with fork oil and knock down the sharp edge.

You need to replace your bushings more often and I do them when I change my oil… they are cheap. it’s not just the black teflon that wears the back side wears as well and causes there to be additional lateral movement between the stanchion and upper tube which causes binding and stiction to occur. 

KYBs can leak when they get really cold. I’ve seen brand new seals do this. I’d check to see if there’s any dirt or sand under the seal and if that fixes it…I’d be on my way and I’d rebuild the forks on whatever schedule works for you. 

I service my forks every 20 hours and replace the bushings. I use the seal bullet tool to remove the seals and clean them real good. I haven't had a seal leak in 200 hours of riding.

Using a feeler gauge or scraper to remove dirt works great only if there is no rock nick or an imperfection in the lower slider. Seals don't necessarily get damaged when you remove them IF you heat up the tubes ahead of time. That being said, I would always replace bushings and seals once there is any dirt or sand that gets in to the seals. the grit imbeds into the bushings, and creates friction and scratches in the lower and upper tubes.

Service intervals can also be hard to quantify. 30 hours on a sand track is twice as hard on the suspension fluids (estimate of course) then 30 hours on a SX track.

Just my $.02