The forks are EXR Supra, which are technically same as MX comp I believe
1 side coil & 1 side air but 120mm travel and I think were OEM.
They are loosing air, I had to pump them up mid ride last night.
Does the "Bomber 30mm (2xOil - 2xDust)" seal kit fix the problem or are there another part that needs replacing.
Maybe it's time for newer forks 🙂
I'm assuming they're like alot of the other marzocchis "air" forks, where its actually just air assisted preload? Not a proper sealed air cartridge?
If so, I wouldnt have thought the seal kit wouldnt fix it - the air is pumped into the top of the fork leg but I cant see how it would leak out of the seals as there is a load of oil it would have to go through to be able to leak out? I think this is correct. Those seals cant be air tight anyway, as they let oil leak through occassionally.
perhaps the valve is dodgy on the top of the fork leg?
The open bath fork the seals are air tight and are all that holds the air in. the main seal at the top of the slider is a proper hydraulic seal that is air tight.
This is how all open bath forks work
Probably replace both the valve cores as a starter. Easy to do. Might solve the problem. Check tightness of valve core
The open bath fork the seals are air tight and are all that holds the air in. the main seal at the top of the slider is a proper hydraulic seal that is air tight.This is how all open bath forks work
I dont think they are air tight, since they let oil past them.
Thanks, will check the valve core first
Think it's gonna be new seals though
The seals arent air tight though? On my bro's bike, he has 2007 mx comps. The seals let oil past them (it appears on the fork stanchions) but they still hold air.
If you think about it, you put air in the top of the fork leg, below the air is a load of oil. Does the air pass through the oil to enable it to leak out? I doubt it.
David thats how they work. You need to take a set apart.
The seal on the top of the slider is the only air seal. The seals are airtight.
Ive taken plenty of sets apart. The seals in the fork legs (oil and dust) arent air tight as they let oil past
Am I being stupid?
The only place for air to leak is the valve or through a dodgy o-ring seal on the top cap (although i doubt this since the top cap has about a 15mm threaded section)
Or are we talking about different forks?
david - the diffference between open bath and cartridge forks. Open bath the seal on the top of the slider is a full hydraulic seal.
Oil can be carried thru the seal in tiny amounts - if there is a lot theseal has goneand the fork will no longer hold air
I know these forks - I had a set on my 04 Enduro.
As others have said, the first thing to check is the valve core. Valve cores are pennies, replacing it would be my first job.
Yes, but if a seal lets oil pass, then surely air can pass (air particles/whatever you call them are smaller than oil particles)
What Im trying to say is that the air will never get to these seals since there is a large volume of oil in the way. Does that make sense? Or am I wrong?
Or am I wrong?
Yes.
The air fills everywhere inside the fork, it is on top of the oil. The seals are air tight (Marzocchi made pumps and seals first and foremost, forks were a 'sideline'). If they leak oil they are probably damaged. Mine don't (2006, original seals), and they shouldn't. Marzocchi say to lubricate the seals after every ride.
2006 Owners Manual: Marzocchi lubricates the dust seals of its forks with grease to help the stanchion tubes slide easier, particularly when the forks have not been used for a long period of time. Use of the forks can melt the grease, causing it to stick to the stanchions, and give the appearance of an oil leak.
Ok, that makes sense to me I guess. After thinking about it for about 10 seconds, I've realised I was initially being thick as ****, of course air can pass through oil, especially under pressure.