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2011 EC 125 clutch slave cylinder problem

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Hey guys,

 Just picked up my wife a 2011 EC 125 a few weeks back, bought it knowing something was up with the clutch, but seems to be possibly be deeper then I first thought. Please excuse me if I use the wrong terminology, but the slave cylinder has a o-ring around the piston, this o-ring is proving to be hard to find a exact match in size. I have gotten close but the problem is, it acts like the piston is having to travel to far out of the cylinder and hangs the o-ring when being pushed back in. Sort of like the plunger rod may be to short. I have found online where someone had the same problem on the same bike, but never said how or if it was fixed. I have also found a GG replacement o-ring kit, but at $75 I want to make sure it want do the same thing when I put it in. Anybody have similar problems?

 

Thanks in advance!

Cody

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More info would be helpful. What was the clutch doing before you tore into it?

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There is a steel ball (approx 5mm) between the slave piston and the push rod.  If missing, the slave piston will overtravel from the housing.  Also, the type of masters and fluids have changed back and forth over the years, AJP/Magura, oil/brake fluid.  You need the correct oring material in addition to size.  Measuring the existing one is of limited value because the material will swell if incorrect.  GG doesn't use any off size special stuff if a standard size will do.  Sometimes the actual size is listed in the parts manual.  I had an '01 125 and its the same slave.  BunaN (Nitrile) fine for oil but not for brakle fluid.  This applies to master rebuild kits as well.

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Basically the clutch would work fine for a bit, then you would lose all the pedal, the you take the slave off, the o-ring would be pinched between the piston and cylinder wall and fluid would pass by the oring. Does that make sense?

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Funny, I just happened to have an '11 parts book handy and no steel ball shown.  Perhaps things have changed but with GG ??  Also there should be a spring in that slave behind the piston, that will push the piston out of the slave housing if it is not retained while being removed.  Maybe this is not your problem and you just need a good bleed.  If it is overtraveling, something is dimmensionally wrong, missing, etc.

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Thanks GP, believe it or not, this one does have the ball made in the piston you are referring to, but there is no spring behind the piston, Doesn't really look like there has ever been one. Also this clutch runs mineral oil, and I'm using a EDPM o-ring which supposedly is meant to be used with it, I think. Could not having this spring in place be my problem? I would think missing parts wouldn't help, but I'm trying to think how or that would cause the problem I'm having. Thank you for your help.

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Not a missing spring, that woudn't matter much and not all the slaves had them.  Some also had retention rings/circlips to capture the piston.  What I'm talking about is something is not right in the parts stack, so that the clutch is not able to return the piston far enough into the bore.  The fluid takes up this xtra space with a few repetative pulls until the piston overtravels.  Go through the clutch parts compared to the drawings / parts list.  Shouldn't be that hard to figure out.  Is this a new or used bike thats been apart?  Wrong clutch pack (too thick) could change this offset and possibly do this to.  FWIW, a Hinson for a Honda CR125 is a good mod as the stock basket is not that good.

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Gotcha, I found a parts diagram, I will check the clutch pak tonite and make sure everything is in the correct position. Its a used bike, not sure if its ever been into or not.

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Sounds like your on top of it with the faulty o ring theory. The only other thing may be the pressure plate is not properly seated on the hub.

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Not sure about the '11 but the older 125 clutch parts were junk and never worked right.  A full Hinson setup from a CR solved the problem.

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