|12-03-2011, 12:11 PM||#1|
Joined: Aug 2011
last week when i was in slow moving traffic the clutch lever got very very soft and when i pulled the lever and tried to change gear it was a struggle,
when i slowly leave it out when taking off it bites straight away, there is no play before it engages,
so i drained the fluid ( its a hydraulic clutch) and cleaned the reservoir and put new fluid in, i couldnt find mineral oil so i got automatic tran fluid, does the trick
today when driving through town in slow moving trafic it started happening again,
but for some reason when i drive on the lever sorts itself out, the faster i go the better it gets,
but when im slow moving it gets soft and spongy again,
now i know if i bled it,it might sort it,
but it will only happen again id say,
i know its not the ATF cuz it happend last week with mineral oil in it,
ATF seems to do the trick across the ktm forums
the clutch felt fine all week too, changing gear no probs with the ATF in it
when i pump the clutch its gets better,
its more than likely a leak in either the slave cylinder or master cylinder,
is there any way of checking where the leak is?
its ktm 660,hydraulic clutch
|12-03-2011, 05:21 PM||#2|
Green Chile Eater
Joined: Apr 2009
Location: County Lockup, NM
Sounds like the mastercyl needs rebuilt to me.
|12-03-2011, 09:40 PM||#3|
Joined: Jul 2011
Some ideas for your clutch repair
There is a coil spring inside the clutch master cylinder which can break and when this spring
( which is a compression spring ) breaks the clutch master cylinder piston can fail to extend
fully to its rest position, and this will cause the clutch to engage immediately with little or no
free play. Disassembly of the clutch master cylinder requires use of what we in the US call
"snap ring pliers", an example of which can be seen here :
Once you get the clutch master cylinder disassembled, you can determine whether the spring is
broken and whether the bore of the cylinder is in good condition, and thus know what parts
might be required for repair. Be sure to note the correct order of parts in the clutch master
cylinder assembly, it is easy to assemble it incorrectly and then it won't work properly
( ask me how I know this ! ).
The most likely clutch hydraulic failure is a failure of the clutch slave cylinder, which often
requires only a new O-ring to fix. To check for a leak at the slave cylinder, you can remove the slave cylinder
( removal of the countershaft sprocket beforehand makes this easier ) while LEAVING the slave
connected to the hydraulic line, and devise some method of securing the slave cylinder piston in its
bore so you can then squeeze the hand lever which operates the clutch and determine whether the slave
cylinder is leaking. It is VERY important to determine whether the clutch slave is leaking because mineral oil
contamination of the engine oil can cause damage to the engine, and if the slave is leaking it will leak directly
into the engine's oil supply.
KTM sells a "rebuild kit" for the clutch slave cylinder, but the kit is expensive ( here in the US it costs
around $80. ) and includes a new piston and O-ring for the clutch slave, though the piston itself is unlikely to be
worn, since it doesn't contact the slave cylinder bore during operation. The O-ring and the bore in the body of the
clutch slave cylinder are the wear items in the slave cylinder assembly in a normal wear scenario.
In the event the bore of the slave cylinder is worn such that it is unable to seal even with a new O-ring,
you will need to install an entire new clutch slave cylinder.
If the master cylinder is leaking it will be impossible to remove air from the clutch fluid during the
bleeding process ( this should be evident when you find it impossible to bleed the clutch ).
In the event, a rebuild kit is available from KTM, and provided the bore of the clutch master cylinder
is not worn or scored the rebuild kit can bring the master cylinder back to working condition.
Pentosin CHF 7 hydraulic oil ( which IS mineral oil ) is an excellent choice for use as fluid
in a Magura hydraulic clutch which uses mineral oil, and you should be able to find it at
any shop which works on BMW, Audi, Mercedes, or VW cars, because it is used in the
power steering systems on many of those cars. The viscosity of the Pentosin 7 is very
close to the "Magura Blood" mineral oil which a KTM shop will want to sell you, but the
price per ounce ( cubic centimeter ) for the Pentosin is much less than for the Magura Blood,
plus it's often much easier to find Pentosin. Do NOT use Pentosin CHF 11 or Pentosin 202,
those products are not mineral-oil based and won't work in your Magura clutch system.
Here is some data on Pentosin CHF 7 :
Good luck, and let us know how it goes.
It'sNotTheBike screwed with this post 12-03-2011 at 09:54 PM Reason: clarification
|12-04-2011, 09:00 AM||#4|
Joined: Aug 2011
wow very informing,thanks a lot,
this morning i took apart the master cylinder and slave cylinder,
-i cleaned the seals in both as best i could
-seals in both look fine
-i put on new banjo washers
-connected it back up and bled it and seemed to be working fine
i went out for a blast around town and it started happening again
what i need to know is:
- even though the seals look fine, could they still need to be replaced?
does the piston in the master cylinder need to be greased for it the return back to its normal position (when the clutch lever isn't pressed) more easily?
when the problem started happening again, instead of pumping the clutch fully i just pressed it in till i got resistance, i kept doing that fast a few times and that sorted it,
that seems to me that the piston was a bit stuck and i was just getting it back to its normal position by pressing the lever a small bit? the spring looks ok to me too
|12-04-2011, 10:13 AM||#5|
Joined: Nov 2005
Location: N.V.I, B.C.
I would recommend that you replace the O-ring in the slave and throw a rebuild kit into the master, that should remove all doubt... This thread covers O-Rings:http://www.advrider.com/forums/showthread.php?t=464845
This bit is from the 127k thread on bleeding:
Take the master cover off...
Coat the bleed screw threads with some grease to stop air infiltration... Then using a syringe, vacuum up some mineral oil then push it up through the slave bleed screw to the master to force all the air up ahead of the oil..
Keep an eye on the oil level so it doesn't over flow... Oil level correct then squeeze the lever a bunch of times, it should come up stiff... If it doesn't, it likely still has air in the system so you can try again... First suck the oil out of the master, then repeat the process...
640 A x 2
BC RIDING 2014
gunnerbuck screwed with this post 12-04-2011 at 10:20 AM
|12-04-2011, 11:35 AM||#6|
Joined: Aug 2011
yea i bled from bottom up with syringe,
i have a couple of pics coming of the both cylinders, give me a few mins
|02-21-2015, 09:52 AM||#8|
Joined: Oct 2013
I'm having a problem that I thought was clutch related on my 2010 530exc. Bike acts normal, and clutch feels ok but when you lay into the throttle, the motor revs out and doesn't go anywhere. Obvious answer is the clutch is slipping.
So I got a clutch kit and threw it in. I mic'd all the plates and springs and the new parts mic'd out quite a bit thicker than the old ones so I know there was some wear there and I felt like it should be good to go. Test rode the bike and it felt good at first but then started doing the same thing and got progressively worse just like it did before I changed the clutch.
I unbolted the slave cylinder and when I pulled it out, there was fluid so there was some leaking by of the o ring for sure. I tried to bleed it and put everything back together but it's basically a no go. I'm gonna run to the shop in a few to see what I can do for a new o-ring or whatever but I'm fairly alarmed at the way it acted.
Would fluid between the slave piston and where the rod actuator and outer diaphragm are cause the motor to slip like that? Anybody had a similar problem?
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