2011 FE390 Leaking Clutch Master Cylinder

Whosaberg · Mar 15, 2015

I have had the berg for a year. Love it, but it came with a slight drip that manifested itself on the bolt of the clutch leaver. Traced it to the master cylinder where the plunger/piston enters. Replaced the plunger after cleaning all parts. To the eye, the bore looked good on the MC. Greased oiled and installed all parts. Bled. No leak.

Went out for a couple of slow technical clutch slipping rides. Clutch action is great, if a little firm. But, low and behold, new leak. Much less than before, but nevertheless, magura blood is leaking again.

Got some ideas:

*Overfilled reservior? (hence firm lever action?)
*Bore of MC needs rebuilding/MC replacing
*Preferred OEM or aftermarket replacements (if necessary?)

Any more ideas/similiar experiences/fixes out there?

Cheers Whosaberg.

worstinfinland · Mar 15, 2015

Clean it up and go for another ride and if it still leaks, get a ktm magura clutch master cylinder repair kit.

Whosaberg · Mar 15, 2015

Already replaced the old plunger with a new one, spring etc...What does the rebuild kit contain?

worstinfinland said:
Clean it up and go for another ride and if it still leaks, get a ktm magura clutch master cylinder repair kit.

fe390vt · Mar 16, 2015

seal

all you need is the o ring for the plunger on the slave. It wears out over time due to excessive heat.. Have fixed 2 different berg clutches slaves this way.

Whosaberg · Mar 16, 2015

OK I'm confused. So if the O ring goes on the slave then hydraulic clutch fluid will leak from the master cylinder on the handlebar? Is it an increased pressure thing?

fe390vt said:
all you need is the o ring for the plunger on the slave. It wears out over time due to excessive heat.. Have fixed 2 different berg clutches slaves this way.

fe390vt · Mar 16, 2015

engine oil is entering the hydraulic line causing the master to overfill. Replace o ring and clean clutch lines.

berglsmerg · Mar 17, 2015

The slave side of the main shaft is pressure fed at up to 58 psi.

I have loss of fluid from the MC, just ordered a new piston. Ktm genuine repair set is 123 aud! Got a genuine magura set for 87 aud

Whosaberg · Mar 17, 2015

OK, thanks FE390VT. I will check the colour of the new fluid in the master and see if that the cause. Any hints on which is cheaper, KTM or Megura OEM?

Whosaberg · Mar 17, 2015

Ok makes sense. Put new master piston plunger in and clutch feels very pressured...harder than I remember. Leaking. Must be, as you say, filling with engine oil. I am looking at either buying a whole new OEM slave cylinder from KTM or and aftermarket product, as the megura slave has an inherent fault with this problem...only one O ring, so the piston wobbles and wears the cylinder out.

If you want to buy just the O ring from KTM HUSA then good luck. They only list the whole slave cylinder as a a part number. There is rumour that the KTM 400 O ring is sold seperately for some strange reason. Part number is 54832067000. I'll phone and see if this is true. There is also an aftermarket O ring made of the same material (Viton). I found this post on Thumper Talk:

"I know this is an old thread, but the problem still exists even on 2012 FE's, so I thought I'd update the thread.
Both KTM and Berg like to **** us ! The O-rings that they won't sell us are easily available. They are an imperial size 2-021 Viton, or BS-021 Viton, depending on which market your supplier sources them from. The metric sizing is 23.52 I/D x 1.78mm. Ensure you order the Viton material for use with Magura Blood mineral oil. They are cheap too . . . In fact, I bought a handful, so if anyone needs one, I'm happy to share"

fe390vt · Mar 18, 2015

o ring

don't quote me on this, but I think the countershaft o ring is the same size. I believe the slave cylinder is not wobbling. The o-ring just hardens over time due to high heat from the engine.. I forget how but I was able to order just o rings. I may have found the size and ordered generic viton o rings... Anyway, it fixed my problem.

whapworth · Feb 28, 2018

this is driving me crazy

i've rebuilt the slave, replace the plunger on the MC, and still having issues with this.

oil just starts appearing near the lever bolt / sleeve.

i ride for about 3 hours and then start to lose the lever, and open up the MC and there is nothing in the resevoir.

i've now gone ahead a purchased a replacement Magura MC, but not convinced that's going to do anything either...making riding my 570FE virtually impossible and not at all confidence inspiring.

any help greatly appreciate

2011 FE390 Leaking Clutch Master Cylinder

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