Hi!
I own a Specialized Stumpjumper FSR XC Pro, equipped with a Rockshox SID Hydrair XC Suspension Fork. These days, I noticed that it loses air quite fast, bottoming out only in a few hours after having been pumped. I asked a local bike shop for an opinion about why that happens, and the guy there told me that the valve is not suited to the fork, but improvised. He also told me that a suited valve for this type of fork is hard to find and that, if I wanted to fix the problem, I should buy another fork, given the fact that valves for this type are really hard to find.

I sought the internet a bit, and I found some versions of valves, but I'm not sure whether they're what I'm looking for or not. Some examples are of products from amazon, sram or chainreactioncycles, but unfortunately I cannot post the link to them. I will try to add a comment containing the links.

So, I thought of asking you guys for help. Do you happen to know what I need? Can I actually replace the valve, or do I have to entirely change the fork? Are the links even close to what I'm looking for? If not, what else am I looking for?

I'll also attach a picture of the actual fork and of the valve.

Thank you!!

argh, I still can't post the links. Unfortunately. I could... pm them to those who are interested? Dunno...

Is it at all possible that the valve is OK, and the leak is related to all the rust at it's base?

Can't believe specialized is going to use a fork with a valve that can't be serviced or changed ,,,

Specialized didn't spec the valve, and had no choice in the matter. They spec'd the fork, a Rockshox SID, and Rockshox made the valve decision.

Looking at the photo, I suspect that the suggestion to replace the fork was based on the overall condition, rather than just the valve

Don't they just use a schrader valve ?

Removing the fork from the bike, and using a bucket of water, one should be able to locate the leak.

Valve cores are often replaceable, and are pretty standard. So, if the core is leaking, then that would be a quick fix.

If the treads where the valve are screwed in are leaking, then some teflon pipe tape or goop might help.

If is't only about diagnosis, it's much simpler. Mix up a batch of soap water. Put some on the end of the valve, and some at the base. Wait. A valve leak will blow bubbles from the top of the valve, if it's leaking t the base, that's where it'll bubble.

Valve leaks are usually easy enough to repair, unless there's rust within the valve body, which would call for a replacement. If it's leaking at the base, that may be repairable with pipe dope, but it's still up to the OP to decide about the fork's overall condition and whether he's really looking to replace it anyway.

The valve on the specific fork in question was not installed by either Specialized or RockShox. Look at the picture. That fork is THRASHED. There's no manufacturer conspiracy going on here.

The Hydra Air has the valve recessed in to the cap at the top of the fork leg. (took 45 seconds on google to find a picture of the fork as stock) This requires a shock pump, which is a small-volume, high-pressure pump, designed specifically to service air/oil shocks (I remember this from the MAG-21 days)
Shock pumps have a narrow, low profile chuck, designed to fit recessed fill valves.

It looks like the bike's prevous owner removed or drilled out the fork cap, and screwed in an external schrader valve fitting so a bicycle tire pump could be used to top off the air pressure.

The fill valve is only the end of the system seals and pistons that makes an air shock work. Dirt, wear, age, and other factors can make those seals wear out and fail. They require regular maintenance and periodic rebuilds.
Air/Oil shocks do not like to be dirty and neglected.

Rebuild kits and spare parts can be available, but usually only for the higher-end models, and only the last generation or so. I have a ~2006 Cannondale Headshok, that needs a rebuild, but there are almost no parts to be found.
You may be in the same situation. IF you can even find the parts, the fork may not be worth the time and cost to rebuild.

Doesn.t look rusty at all around the valve... That might only be some dust.
It.s rather the paint of the fork that is falling off because of the water and rust, but I totally doubt that has anything to do with my problem

Um... so Specialized collaborated with Rockshox and decided to put this particular fork on this bike? I thought the previous owner actually chose the fork. I somehow assumed that the original model of the bike came with an original Specialized fork - but then again, I don.t really know much of the matter.

Also are you only putting air in that right side stanchion? The SID Hydra Air has an air damper on the right and the air spring assembly on the left. This guy here is what you would need to pump up the SID Problem Solvers 1999 and 2000 Adapter > Accessories > Pumps & Inflation > Shock Pumps | Jenson USA. Either way, a fork that old probably needs new seals, fresh oil, complete rebuild, and that's providing its even worth doing to a fork in that condition.

Yeah, that's where the air goes.

What would the complete rebuild suppose? And.. excuse my ignorance, but how does it help the fork? Is it customary maintenance?

Did you do a soap bubble test to see if it's leaking at the top or base of the valve?

Either way, it seems more likely that the leak is at the other end, namely at the piston O-ring which is a wearing part.

Here's the service manual for the fork. I also have an FSR XC Pro.

https://my-sport.spb.ru/manual_1/1999...%20sl%20xl.pdf

That fork requires air on both sides. The part with the bodged schrader valve sticking out is the Hydra Air damper. The left stanchion with the recessed schrader valve is the actual air spring. In fact, you might try unscrewing the valve from the right stanchion to see if it's just the pump adapter that I linked in my previous post.

A rebuild will include new o-ring seals, new dust wipers and foam rings, and fresh oil in the fork. A fork as old as yours, if it hasn't had a rebuild or oil change, might not even have much oil in it right now. I performed a rebuild on the same model fork a few weeks ago and it was almost completely dry, and badly in need of the service. Rockshox recommends an oil change ever 25 riding hours, and a full rebuild every 50-100 hours if memory serves.