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Bleeding the hydraulic clutch - at wit's end!

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Hello,

I'm new here and decided to ask the experts about an issue we've been having for about 3 weeks now.  My boys and I are very frustrated with a 2007 85SX project bike that we purchased.  We bought it as a project and rebuilt the entire top and bottom end.  The bike runs great!  What we didn't realize was that the clutch didn't work when we bought the bike.  The seller did tell us that the engine needed work so we knew that going in.  

We've tried multiple ways of bleeding the clutch; using a syringe and pushing fluid from the slave cylinder to the master, and also the usual way of squeezing the handle and bleeding at the slave.  We have rebuilt the master cylinder and replaced the slave cylinder with a new one without any success.

The pressure cap moves about 2mm but it doesn't seem far enough to disengage the clutch.  When we shift into first with the bike running, it dies.  When we shift into first without the bike running with the clutch pulled it then it doesn't roll.  Any ideas would be wonderful as I'd like them to be able to ride it.

Thanks!
Rich

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I'm no expert, but as someone else pointed out for a similar problem, the plates may be warped or the basket/hub notched. I would probably pull it apart and check it on a piece of glass if you think you bled it enough already.

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I'm no expert, but as someone else pointed out for a similar problem, the plates may be warped or the basket/hub notched. I would probably pull it apart and check it on a piece of glass if you think you bled it enough already.

 

We did check the plates and the basket when we rebuilt it and everything looked good.  The only thing we didn't replace was the hose and the master cylinder itself.  We're to the point of taking it to the dealer to have it fixed.  Bummer since we are still learning.

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Thank you, awesome video!  We will give this a try in the morning.  Hopefully this will do the job for us.

 

Rich

 

Well, tried those few things to no avail.  We went back through and made sure all of the parts were in there also.  We had it running a few weeks ago but now it is only moving about 2mm.  I hate to say it, but I think we're going to take it in.

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Sorry the video didn't help? Hope you get things sorted out. Keep us posted as to what the problem was when you find out.

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2mm at the clutch is plenty. Did y'all actually have the clutch plats apart, are they stuck together?

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I had a similar problem work my 2000 exc 250 when I bought it, it has a rekluse in it and the buy I purchased it from said the clutch line was leaking so the manual clutch didn't work. I replaced the line and had to use a vacuum pump and hook it to the bleeder valve and keep adding fluid to the rest until there were no bubbles coming down thru the line. Hope you can get it worked out all right

Edited by Kayakfish1

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here is my how to

 

Bleeding hyd clutch:
They use oil instead of brake fluid until 06. These things are sweet until you get air or the seals leak. They are not hard to work on, but can be difficult to diagnose at first. Use Magura Blood or synth 5w fork oil or synth auto trans fluid.

The #1 thing is air in the system. This can happen cuz you took something apart to work on it,bike was upside down in a crash,or a seal has started leaking. The symptoms will be the clutch suddenly quits working right. The lever is right at the bar and when you put it in gear the lever has no feel and the bike takes off on you. This is low fluid or extreme air in there.

There is a MC rebuild kit avail, but not a slave rebuild. You can however use a new o-ring in the slave and fix most of them. This o-ring isnt avail by KTM for the slave, but there is another one in the engine that is just the right size.The stock size is #0770002210, the larger size is #0770230020. If the bore is scratched or has a shiny spot on it you will need to polish it with 800 grit paper and then put the new o-ring in. Be careful of the spring and ball in there as they may fly out. Put the slave in a clear plastic bag and then pop the piston out by pulling the lever in and it will push the piston out. There are several thicknesses of gaskets for the slave so be sure to match it by measuring it.

To bleed you must first have a large syringe like found at a farm or vet supply store. You use it and a piece of tubing that will fit snuggly over the bleed nipple. Take the nipple off and thoroughly clean the dirt out of it or you will push the dirt into the slave and the grit will ruin it. Take off the top cover of the MC and loosen it at the bar to get the reservoir level. If the fluid isnt covering the orifice in there then you have a leak somewhere. It is a sealed system.THE LEVER MUST BE FULLY OUT ALL THE WAY OR IT WONT BLEED. You can loosen the adjusting knob or tie it open somehow if you have problems. If you have bark busters be sure the lever isnt hitting as it may not be fully extended if it does hit.

Loosen the slave bleeder, put the hose on it, and push the fluid up form the bottom. The fluid will go in firmly, but not hard. If its real hard then there is dirt in the bleeder or the lever isnt out all the way. The fluid will overflow and spill on the bike and floor so be sure you have paper down or something to catch the mess. Tighten the bleeder. Then work the lever in n out a little and tap on the line in the upper area to try n work out a few more bubbles. You may see very tiny bubbles come out of the MC hole.

If the clutch doesnt work, do it again. Make sure there is no high loop or area where the hose is above the MC. If the clutch works, but fades and then returns later you may have a bad MC. If after a ride or two the clutch goes away again then you need to check the reservoir. If its low again then you have a bad o-ring in the slave. The oil probly wont run out anywhere as it goes into the gearbox along the clutch rod.

.......................................

 

It may also be that the plates are just stuck...I would start the bike and let it warm up. Then kill it and push start it by being in neutral and then putting it in gear and seat bouncing it at the same time. This will often break the plates loose and problem solved. It may take a few tries to get it to bump start...........or get it started and then push the bike and click it into gear and ride it off. Rev it and shift gears, pull in clutch at 3rd gear speed and jam on rear brake to get clutch to release.

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Once the system is primed by back bleeding you need to remove excess air trapped in slave and banjos or the clutch will drag and not fully disengage.

First remove reservoir cap and remove slave cylinder from bike with line still attached. Pump clutch lever about 10-15 times to extend piston in slave. Now compress slave back into housing and you will see air bubbles being pushed into master reservoir. Take clutch lever and flick it a bunch of times( grab and let go snapping it back fast) this will also loosen air in master and banjo and line. Repeat this process a bunch of times until no air is seen in reservoir and clutch pull feels strong.

If clutch works good but bike still jumps when dropping into first from neutral then the frictions need replaced. The frictions and steels are sticking and not disengaging. This is assuming the basket has no notching.

I have experienced the exact issue on my 250sx. Good bleed, and new clutch pack solved all issues.

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