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Old 02-05-2012, 12:20 AM   #1
mousitsas OP
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closed cartridge forks

Fellow tinkerers,
Would you bother fitting closed cartridge forks from sxf250 or the similar ohlins to an SE? The latter will have to be sleeved to fit in the tripples and are 45 (or 46mm diam).
Will they perform better for 50/50 use than the oem's with similar mods if revalved and resprung?
Will they be more maintenance intensive?


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Old 02-05-2012, 01:22 AM   #2
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Are you sure they need sleeving?
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Old 02-05-2012, 01:51 AM   #3
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Quote:
Originally Posted by Peanuts View Post
Are you sure they need sleeving?
If I remember well, they are couple of mm less than stock, at both yokes and have slightly different caliper mounts. Thats the ohlins, the wp should be identical.
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Old 02-05-2012, 09:25 AM   #4
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I just got mine back from my tuner. His comments on the front valving were, "what were they thinking"? He upgraded them to two stage with a midvalve, should be plush at extension then very firm, unlike stock which just opened the shims and blew thru the stroke.

I was just considering a longer travel OC EXC fork a few weeks ago and decided to leave the standard length stuff and see where it ends up with a good base setting. Nothing wrong with the OC forks if they are set up right. With valving that works from the top to the bottom I expect a huge increase in control. I race mine.
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Old 02-06-2012, 02:25 AM   #5
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"He upgraded them to two stage with a midvalve,"

How did he add a midvalve without going to closed cartridge forks?


"plush at extension then very firm,"

These forks don't have any positional changes in damping, except for the last 1" before bottoming.


Sounds like you got some smoke blown up something.
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Old 02-06-2012, 07:58 AM   #6
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He is a very experienced tuner, work with alot of big names here before they went to full factory rides, he knows what he is doing. I may have misunderstood his terminology. Maybe he was describing two stage valving instead of the single stage it had in terms I could more easily understand?

So far his description is dead on, it is softer at extension and gets very firm as it goes deeper. It's a far cry from stock where it just blew threw and rode deep/ bottomed all the time.
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Old 02-06-2012, 09:41 AM   #7
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All forks have a mid-valve...


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Old 02-06-2012, 10:09 AM   #8
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Hmmmmmmmmmmmmmm...

So, are the stock SE forks valved single stage and is there anything significant on the midvalve that actually works to increase damping at that stage. I admid to being a suspension goober. I fumble with the terms and values of various components. I've read alot about this and that but base valve float and fluid dynamics are well above my pay grade.

My tuner had never been inside a SE fork, and he said it was goofy at the least. He does all my EXC and SXf stuff and it works wonderfully. He admits we may need to tinker with his baseline but I can tell already it is far better than the wallowing stock settings.

I expected the shims in the forks to be cupped based on comments here but he said they were all still good after 6k of off road. Huge but good!
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Old 02-06-2012, 12:49 PM   #9
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OK, here's the longer more correct answer. There is usually a check valve that can be called a 'mid valve'. Adding restriction to this valve that creates damping gets into problems with cavitation unless you go to a closed cartridge fork.

The standard open cart fork is intended for enduro/trail riding where you rarely jump very high and don't through a series of deep woops. Enduro/trail riding wants the suspension to blow through most of the travel and return quickly to get more traction. Within reason, you rarely hit any thing over 10" high at high suspension velocities. These are the plushest feeling forks. They feel loose and under dampened if you take it to a MX track. All the big orange twins have open cart forks.

By adding damping to the mid-valve you'll get much more compression damping to help limit travel. This is only an advantage if you get lots of air or are slamming a series of 3ft deep woops. The mid-valve damping can also help with traction on hard pack where you may have a lot of small travel high velocity bumps. It can make the forks feel harsh and painful, the opposite of plush.

There is a potential problem with mid-valve damping that you'll cause cavitation, where the oil foams. You'll hit the first woop and get dampening, the next woop will get less damping and the thrid and remainibng woops will get very little damping because the oil has foamed up. This problem is very hard to diagnose. This is the reason for closed cart forks with a pressure chamber to hold a big compression valve.

Mid-valve shims also need to be very thin and flexible. They will often bend permanently on the first big hit.

Going to two stage damping on the existing compression valve is a way to increase damping without making it harsh on lower velocities. Instead of a linear damping curve, you'll now have a non-linear damping/velocity curve.

There are cones that shut off oil flow as the fork nears the end of the travel. This is the only positional damping change.

Adding more oil will make the fork resist bottoming. It acts like a progressive spring.

You must be riding this bike much more aggressively than most people. I would probably find your new setup some what harsh for the type of riding that I do - slower, sitdown, trail riding.
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Old 02-06-2012, 01:26 PM   #10
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Not sure where Zuber gets his info, but there is a mid valve in all late model WP forks, and it's responsible for about 80% of your damping. The base valve only responds to fluid displaced by the damper rod as it enters the oil chamber.

Sounds like your tuner knows what he's doing, but he should set your mid valve float prior to installing a two stage stack. Good luck...


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Old 02-06-2012, 02:45 PM   #11
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Yes, I may be using it a lil more agressively than some?

Most of my riding is deep sand whooped junk at race pace. Most of that the big gal could handle with the tail wagging and the forks bottoming but the weight seemed to force it down the trail like a train off the tracks. I expect to be less of a rag doll and more in control of where it actually goes now.

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