Marzo fork oil level

At the bottom of the Allen head in the alloy fork leg cap is a screw head, no?
This can be unscrewed to adjust internal pressure.
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If you unscrew that screw you will find a spring and a ball. An airway passes through to the bottom of the cap. The taper where the countersunk screw fits has ridges, presumably to let air pass. To my eyes it looks like a very agricultural one-way valve.
 
Legs said:
If you unscrew that screw you will find a spring and a ball. An airway passes through to the bottom of the cap. The taper where the countersunk screw fits has ridges, presumably to let air pass. To my eyes it looks like a very agricultural one-way valve.
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It is a one way valve. It's not an air assisted fork.

Paul
 
Paul Marx said:
It is a one way valve. It's not an air assisted fork.

Paul
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apparently its a pressure relief valve according to Richard slater and if you need a spring there the same as the bic biro
 
Shajota said:
Well, that may be true in the technical sense, but try riding one without air assistance (gap).... :D
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Works fine in orbit.

That's not air assistance, that's oil level. Can't understand why it's often refered to as air gap. Do you talk about air gap when checking oil level in an engine?

Paul
 
It is a one way valve. It's not an air assisted fork.
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Never said it was an air assisted valve. I believe it is designed to relieve air pressure in the forks when compressed.
I drilled mine out and inserted schreader valves cut from old inner tubes. Haven't had a blown fork seal since.
But what the hell do I know, I'm not a mechanic :D.
 
Paul Marx said:
Works fine in orbit.

That's not air assistance, that's oil level. Can't understand why it's often refered to as air gap. Do you talk about air gap when checking oil level in an engine?

Paul
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Yes, it's all about the oil level, but of course that effects the air gap, so however you wish to term it ::)
I think the air gap is mostly referred to as it is the most accurate to measure to get both forks the same, rather than just rely on a particular amount of oil being put in, regardless of any other factors such as any oil remaining in a fork etc.
Oil level in an engine hardly requires the same accuracy of measuring..... (and neither do forks if you so wish!!)
 
Firstly, don't you need to ascertain the length of the fork legs before talking about air gap (many variants of Marzo forks?) And secondly, if it's a one way air valve, once it's blown all the air out, doesn't it negate the air gap (the air compression effect on springing)?
 
Piranha Brother 2 said:
Firstly, don't you need to ascertain the length of the fork legs before talking about air gap (many variants of Marzo forks?) And secondly, if it's a one way air valve, once it's blown all the air out, doesn't it negate the air gap (the air compression effect on springing)?
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To a certain degree, yes. 

The springs are quite stiff, much stronger and shorter than a biro spring.  But, as these valves are usually full of crud and rarely work as they should, they may as well be disregarded altogether...

As I see it, the valves' purpose is to sustain a low vacuum inside the fork legs to avoid seals blowing.

piet
 
Well mine are probably full of crud and no longer work. I've never removed them. Bike has never blown seals either but have worn a few out.
How does the Cerianis work without them.
As for the air gap I thought it was just a measurement for oil level rather than a volume of air.
As an aside, the replacement after market for legs I fitted a few years ago have rust spots in the crome.
Considering the lack of use and very little wet mileage the chrome must be pretty shit!!!
 
Terry,

I regularly opened the Shrader valves on the M1R forks to release pressure.  Noticing that the forks gradually become firmer tells me they pump themselves up  by sucking air in through the oil seals.  I have since removed the valve internals and fitted caps with  small breather holes.  The fork now hisses and puffs, but no longer stiffens up after 100km of bumpy road surface.

The stock "valves" are quite restrictive, so oil level aka air gap does have a definite influence on the fork springing action.  The higher the oil level, the more progression is attained from the springs.  No influence on damping though.

piet
 
My take, there are accessory gadgets you can get for dirtbikes similar to those gadgets that allow any excess air pressure to be bleed off. You push the button and pissss, outcome any build up of air pressure. Those air assist forks that you added air too would blow seals very easily, the better kits and that's wasn't saying much connected both forks together and allowed the tink amounts of air without losing any when you disconnected the pump. The pumps were just enlarged syringes about 100mm long and 20mm wide, it only took 2 or 3 strokes to add the tiny amounts the system needed. Waste of time in the end. Legs Shrader valve would be an easy way to bleed them as well. Air out is good, adding air is not. Nobody does air forks now.
 
There's no valves in the tops of my Marzo forks on the Jota, but the Marzo forks on my MHR Ducati came with Schrader valves in them. Their existence led some owners to believe that you should pump the forks up with air. There was a whole lot of theorising on the Ducati forum about how much pressure you should run in the forks. Opinions varied from zero to about 30psi. I'm in the zero camp. I just use them to bleed off the air occasionally.

The original forks on my Kawasaki Z1300 had a balance pipe between them to ensure they were both at the same pressure. Not a bad idea. Those forks have long since been replaced with a leading link type suspension for sidecar use, but I still have them stashed away somewhere.
 
Dellortoman said:
There's no valves in the tops of my Marzo forks on the Jota, but the Marzo forks on my MHR Ducati came with Schrader valves in them. Their existence led some owners to believe that you should pump the forks up with air. There was a whole lot of theorising on the Ducati forum about how much pressure you should run in the forks. Opinions varied from zero to about 30psi. I'm in the zero camp. I just use them to bleed off the air occasionally.

The original forks on my Kawasaki Z1300 had a balance pipe between them to ensure they were both at the same pressure. Not a bad idea. Those forks have long since been replaced with a leading link type suspension for sidecar use, but I still have them stashed away somewhere.
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Cam,

If they are stock Laverda fitments, you should see a slotted screw head at the bottom of the hex sockets of the stanchion caps.  If you remove this countersunk screw, you should find a spring and tiny steel ball amoung the crud and rust.  The countersink of the bore has ridges to prevent the screw head completely sealing the opening.

The 35mm Cerianis fitted to the 750s had a similar set up, deleted on the 38mm Cerianis. 

piet
 
About to fill the forks with oil. Plan is, 150mm of gap, drilled a second hole and set to 3 turns. I'll order a set of the blue springs and give them ago.
I know nothing about suspension and what changes/settings do what. I just ride the fuckers!!! :D
 
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