KYB bleed problem

I'm having problems bleeding the inner chamber and hope you can help.

I've worked on this style of fork before and never had a problem but these forks were previous modified by a local suspension shop and I have a feeling they messed something up.

1. When I bleed the inner chamber and get all done I normally push the rebound rod into the chamber to release any excess oil. As you know it will blow out the two holes on the side of the chamber.

With this fork just as soon as I start pushing on the rod, oil starts coming out the two holes and the rod will not even start to extend on it's own.

2. The suspension shop was suppose to have changed the TC pressure springs and I kind of think that might be the problem. On these forks there is about a half inch of free play between the spring and the floating plastic piston. I'm thinking that the springs they put in are to short. Shouldn't the spring at least come close to contacting the piston?

Any help you can give will be appreciated.

sounds liek the seal has gone on the floating piston inner, or outer.

There are a couple of different length ICS springs on the Kybs. Some ran a spacer some did not. It sounds like the seal on the ICS piston is leaking as well. It could have been damaged when changing the springs. (crap mog you beat me to it. We must of been typing at the same time!)

Stock KYB pressure springs are not preloaded but there is not much float between the plastic piston and spring. The piston would engage the spring pretty quickly when compressing the damper rod into the body.

A half inch seems like an awful lot of play.

You have two potential issues to investigate

1. The pressure springs could be the only source of your problems. Only way to know would be to measure the stock spring length and compare it to the current springs. If the current springs are much shorter I would think something is missing (spacer) or wrong.

2. Your piston seal could be leaking from neglectful disassembly (catching seal on threads or over zealous heating) or good old fashion wear n tear. The easiest way I can think of to check if your piston seal is leaking would be to re-install the stock pressure springs that we know work and rebleed/assemble.

If all goes well then you know it was just the springs. If the rod is being sucked up into the damper/not retracting back out then its the seal. And I would replace both cartridge and piston seal to be safe.

Thanks guys.

Unfortunately I don't have the stock springs as the shop that did the work has/had them. It's not my bike and the current owner isn't the one who had the work done.

I did replace the ICS inner seal but not the outers. I just talked to DaveJ and he said I should check the inner seal to make sure I put it in the right direction. I will check it but I'm 99% sure it is correct as I was very careful about that.

I did not however change the outer seals so I'll look at that next. They looked ok but maybe they are not so good after all.

i think the ics should be 105mm total, 95 + spacer or 105 without

i think the ics should be 105mm total, 95 + spacer or 105 without

Spacers which come with 95mm springs are 15mm, so total 105mm or 110mm.:smirk:

I thought I'd update this since I fixed the problem. It turns out the outer seals were bad. I replaced them and everything works fine.

Thanks for the replys.

I have a set of stock 05 KX250 IC springs if you need that measurement.

Thanks for the offer but the forks are on the bike now. Seem to work ok so all is good.

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