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Jeremy, your opinion on fork canisters

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#1
I was reading an article in MXA on those Enzo Racing air canisters . From their description, I like the idea and it seems a simple way to overcome my particular problems. I am a big guy. 6ft5 and 280lbs. Bikes just don't fit me. Particularly, I have to run very heavy springs for MX (0.48 Kg/mm) and if I run some pre-load to get bottoming resistance, the forks are not supple enough. So I run the oil level up high to get bottoming resistance and when the track roughens up thru the day the action gets choppy . The idea of being able to vary the action of the "air spring" as my Öhlins handbook puts it seems cost effective. Have you had any experience with these things and can they be fitted to Öhlins forks?
 

Jeremy Wilkey

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#2
Greg,
My take on the canister is fairly simple. The subtank system is a adjustable restrictive barrier as far as I can tell. It's a great idea, I have not actually used one, Ive but have been putting off ordering one from Ross.

I intend to researcha and see if I would get into any legal issues but if I can I'm putting a slighlty diffrent version on WP forks next year.. It's a great idea that I think could be made even beter with a variable orfice / adjustable bleed system.

Jer
 

Jaybird

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#3
Those things are interesting. Since the idea basically is being able to vary the volume of air chamber on top of the oil, sounds like a great way to fine tune.
My question is about the orifice. I think that Ross is using the stock air release screws to connect his gadgets. I'm wondering if the small orifice is not so small that the travel of the air is restricted, which would limit the ability of the adjustment. Would it not be a good idea to maybe bore and tap the orifice in the cap to a larger OD than the tubing ID, used to get to the canisters? That way the most restrictive point would be the flow controls, giving you full adjustment capability. <shrug>
 

Jeremy Wilkey

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#4
Greg,
I have taken a really close look at them and it does appear as if the the threads actually are enlarged. They intresting part about is we are no-longer dealing with fluid restriction, but a gas... So respectively it's not such a big deal. The restrictive barrier on a KYB fork is so small, I'm amazed at how well the non adjustbale version works. (it's using fluid)

I need to point out that I can't actually comment concretely.(having no personal exspereince). I'll see if I can get Ross to make some coments on his system.

Jer
 

Jeremy Wilkey

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#6
Hey all.. I've got a reply back from Ross and he's asked me to post up his comments.. I'll get them from the network tommrow and post them up..

Jer
 

Jaybird

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#7
I've had some experience with pneumatic cylinders and have been involved with the development of some air over oil contraptions in the past. (we went the cheap route using air for power instead of a hydralic pump)
One project I was on we found that, for smoothness, hydralics is far superior to air. Air alone tends to "cushion" a bit when compressed then finally give with great force. But oil tends to be much more consistant from start of stroke to finish.

BTW, I'm building some canisters of my own. I don't like how Ross' flow controls adjustments just turn, I'm going to use detented controls. I'll fill everyone in on how badly it turns out. :confused:
 

Jeremy Wilkey

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#8
Readers,
Here's a paste of Ross's e-mail.. Some of it is rehash but our assements were correct.

I would like to thnak Ross thanks for taking your time to join our discussion.

"The concept of my subtank system is to create a "speed sensitive spring characteristic". As you know, the two elements of suspension are SPRING and DAMPING. The SPRING element is load or position sensitive. If 10 lbs. is applied to a 10 lbs. per inch rated spring, it will compress one inch. 20 lbs. = 2 inches, etc. But it is not speed sensitive, because if 10 lbs. is dropped on the spring, it will compress more than 1 inch, but after bouncing up and down for a while, it will settle at 1 inch of compression. Adding speed to the situation changes the reaction.
The second element is DAMPING, which is speed sensitive. It is like stroking your hand through water: the faster you stroke your hand, the more resistance the water provides. Speed determines the amount of resistant force. But DAMPING is not position sensitive or load sensitive. If a load is placed in the water, it will sink to the bottom. Nothing will hold it in place, only the speed sensitivity will control how fast it sinks.
So the two elements work together to give total suspension action. But my system creates an additional speed sensitive element within the spring characteristic. In a front fork, the TOTAL spring character is determined by the coil spring rate, and the AIR SPRING RATE combined. The AIR SPRING RATE is the compression of the air volume within the fork determined by the oil level. A low oil level provides a large air volume which compresses at a slower progressive rate. A high oil level provides a small air volume which compresses at a faster progressive rate.
The sub tank system provides additional air volume to manipulate. By dividing the total air volume into two "chambers", and separating them with a "restrictive barrier", it is possible to control the compression of the air volume by metering restriction between the two "chambers". The compressing "charge" is created by the inner fork tube entering the outer fork tube. This charge compresses the oil level chamber in the fork. With the sub tank system installed, a high oil level can be set within the fork. The sub tank provides additional air volume, which when combined with the oil level volume is actually providing a large total air chamber volume. When the fork is compressed slowly or uses shorter amounts of stroke, the total air volume of both chambers is compressed equally, giving the sensation of a very low oil level, and the action is soft. But as the fork compression speed increases, or longer amounts of stroke are used, the restrictive barrier prevents equal compression between the two chambers, so the oil level air chamber compresses at a higher rate than the sub tank chamber volume. This gives the sensation of a high oil level in the fork, and the action is firmer. In other words, when the fork is compressed slowly or uses short stroke, it feels like it h as a low oil level. But when the fork is compressed faster, or uses longer stroke, it feels like it has a high oil level. The tuning elements of the system are the volumes of each chamber (oil level and sub tank volume) and restrictive barrier (flow adjustment on sub tank). My system is installed on the stock cap through the air bleed hole, which is drilled out larger and tapped to accept a larger flow fitting. The hoses attach to the cap fittings, and then to the sub tanks. The adjustment flow is the point of greatest restriction.
I hope that this clears up any confusion about the system. The difference between the KAYABA bladder system and my sub tank system is that the restrictive barrier between the two chambers is HYDRAULIC in the bladder system, and PNUEMATIC in the sub tank system. WHich is better? I believe that PNUEMATIC, air restriction is better because air can compress and will not spike. HYDRAULIC, oil restriction is not compressible, so sometimes it spikes. Also, the bladder system is not adjustable, and the sub tank system is. "
 

Jaybird

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#9
I would like to applaud both Ross and You, Jeremy for being the kewl fellas y'all are.

I think it's great when a technical person is so passionate about their trade that they don't hesitate to share the knowledge they have with the rest of us.

High 5's guys! Its folks like yourselves that make this the best sport/hobby in the world.
 
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#10
First, thanks all the great information! I just bought a set from a guy off of Thumper Talk. I will be installing these on my 08' Husky WR250. I have Marrazocci forks, does anyone have any tips on installing these? I read the directions off of Enzo Racing's website, but it only talked about Kayaba, KX & RM setups. Thanks in advance, for any advice!