ICS rate for WP OC-TC conversion

I'm converting my POS WP OC forks to TC

ICS piston will run between the OD of the cart and ID of the lower fork tube.

I'm looking for statistical information on a few different TC set ups so I can guess a starting ICS rate.

I need (i think), rod diameter, fork travel, ICS piston effective diameter or effective area and ICS spring rate for some different forks and what you think of that setup or how it might be improved ICS rate wise. is it advantageous to prelaod ICS springs ?

anything else you guys think might help is greatly appreciated



wouldn't it just be easier to bolt on some complete TC forks?

wouldn't it just be easier to bolt on some complete TC forks?

He doesn't understand such foolishness...if I was the suspicious type I would think he's and "ex" drunk...the type that has to stay busy? :busted::worthy:

IMO he should do EXACTLY that and go play with his kids instead of trying to "fix" an archaic design...kinda like DaveJ with the 03 KYB's...:thumbsup:

you guys are both 100% right

and I think this is the first time I agree with Lew on something he said about my bike :thumbsup:

I've got all the bits ready, the cost was about $40 I can't do a TC fork swap for less than $400 or 500. if going into that sort of money Id go one better and get TTX inserts.

If I'd sold the brand new WP forks way back when I got the bike I'd be able to do it no worries. but I read too many posts saying the Wp stuff can be made to work just fine, the 12mm rods are a big step ahead, cavitation doesn't exist etc etc..........

so.......... anyone got any numbers on any TC forks? the ICS rates are easy to find but the rod diameters, fork travel, ICS piston areas and cart IDs are not.

I'm doing it anyway regardless of the madness, just thought someone might have a few specs, the closer I am with the first attempt the more time I can spend playing with the kids hey lew?

so.......... anyone got any numbers on any TC forks? the ICS rates are easy to find but the rod diameters, fork travel, ICS piston areas and cart IDs are not.

I can give you the specs of a '08 KX250 if you want

we have a 12.5mm rod with 290mm of travel results in 35.6cc oil displaced by the rod. this amount of oil flows through the BV and lifts the free piston.

the cartridge has an ID of 22mm, but that doesn't matter.

with 36mm free piston diameter the 35.6cc of oil lifts the free piston 35mm.

as far as I know all KYB's have 12.5mm rods (showas have 12mm, but haven't some '08 showas 12.5mm rods?)

the '06 YZ250 has almost the same fork dimesions except the cartridge ID of 24mm.

thanks Kawamaha, thats very much appreciated

has anyone got any showa specs? the free piston looks to be roughly the same as KYB from the pics put up from time to time.

got a PM (thanks!) most of this info is on mx-tech website except for the travel of the showas I think its all covered.

I'm guessing its 290-310mm or thereabouts

I'm completely confused.

Are you trying to convert an open bath fork to a dual or closed chamber?

If so, why?

got a PM (thanks!) most of this info is on mx-tech website except for the travel of the showas I think its all covered.

don't trust that page too much, eg they listed a 2007 KX250 with an 28mm cartridge and 225cc oil level :thumbsup:

it has a cartridge ID of 22mm, BV piston 25mm and free piston the assumed 36mm. the oil in the cartridge is below 200cc and the outer chamber is about 310cc ....

Ok rodger the stats are a bit dodgy, it says all the KTM's have TC forks too....

ahh thats a good question Dave the only thing I can say is that I'm not happy with them but whack a set of KYB TC forks on the bike and its all good.

I can give both types of fork enough of a hammering to upset the damping consistency but the OC won't recover quick enough even with cartridge backfill and blowoff springs on the MV, not saying it can't be done just that I know TC forks recover quicker.

the idea comes from Terry Hay who has done this mod before so I kind of assumed it was a good one.

I have a question Dave; what are the advantages if any of an open bath fork over TC and are the same attributes not acheivable with TC?

ok in the TC there is a rod seal and ICS piston drag that can't be good but isn't the nett result of a closed chamber idea that cartridge pressure builds faster so the MV can be more effective resulting in a plusher firmer ride? and if aggrivated to the point of losing it a TC can stuff oil back into the cartridge more effectively than the open chamber idea ?

BushM, i am looking forward to any news and hopefully you make some great picture along the way. If so, will you put them in yr gallery at husa?

Some guys here have lost their tweakers dreams.

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