Hope I can help you here I had a BMW R1100R with a manual clutch not hydraulic.What i would like to tell you is that there is a bearing and it is very small on a non-hydraulic unit and I am sure it is simular on the hydraulic unit! On the end of the tranny near the rear tire you have a clutch slave cylinder that pushes on a clutch rod that goes all the way through the center of the transmission mainshaft and eventually reaches the pressure plate.the small thrust release bearing is located between the slave cylinder and the push rod.On the hydraulic unit it may be inside the clutch slave piston. I had one fail on my manual cluched bike and the pushrod mushroomed near the pressure plate which meant I had to dissasemble almost the entire bike to repair it! If it making noise fix it ASAP! And to the riders loosing your Hydraulic clutch I have also seen the crankcase breather issue on a local riders KTM.Its the same issue as if you were to collapse your brake caliper to replace brake pads and then you have to pump the lever up to get brakes to contact the brake rotor ,crankcase pressure forces your slave piston in and then you must pump the lever to return the clutch slave to its operating range.Now realize that if you are having issues with crankcase pressure pushing your slave in you wont be loosing clutch fluid! If you are loosing clutch fluid then you definatly have a leak and its probably on the slave cylinder
Did you guys ever find out what the problem was here? I am having exactly the same issue on my 06 with 30 000klm. Using the Magura mineral oil. Losing clutch fluid, but cant see any leaks etc. have bled the system several times and makes no difference.
I had this same issue with my 640 Adventure. Clutch action issues and fluid loss started at about 8K miles. Replacing the slave cylinder and piston at 11K miles fixed the problem on my bike (the whole assembly is avail for purchase as a single part PN 50332061044). If the slave piston O-ring starts leaking every pull of the clutch lever will push a little of the mineral oil into the engine. There will be no visible external evidence for the leak. Refilling the master cylinder with fluid will address the symptoms temporarily but won't solve the problem. Replacing the slave cylinder assy. did work and the bike currently has 17K+ miles on it. What I'm not sure about is whether this is likely to be a repeating failure on these bikes. The description of the slave cylinder assembly from the microfiche is "CYLINDER CPL. 125/200'98" i.e. the slave assembly was originally engineered for the 1998 125/200 two stroke race bikes. The slave is also located behind the countershaft sprocket on a fairly hot running engine well out of any possible airflow path. Neither of these factors gives me a huge amount of confidence that the problem isn't a chronic engineering issue.
BOFH is likely right about a leaky slave but you shouldn't have to replace the whole unit... Likely an o-ring refresh will get it working again.... Here's a thread I started a while back pertaining to clutch o-rings: http://www.advrider.com/forums/showthread.php?t=464845
--Hey folks. Haven't been riding or even lurking. After letting my 07 640 A have a two week rest, I took it for a simple spin and lost my clutch just like the OP had described. The bike has been flawless in the 5K miles I have put on it in the last year and a half. The beat clutch is my first mechanical problem. I had planned on taking the bike to the dealer to have it rejeted and figured that they might as well fix the clutch. I'm picking the bike up later today and I was not told what the origional problem was with the clutch. I was told that the system was bled and recharged: "if the problem comes back, a master cylinder (or slave) will need to be rebuilt." I'm tempted to just have them do a rebuild to save me a head ache. Any suggestions of what to look for if I decide to tackle this on my own? Thanks in advance.
just get some orings... they seep the fluid into the oil...mine is now seeping and drains in a 5 hr ride.. what will finally happen is the coating on the inside of the slave wears out ..been there done that.. A 50 cent o ring sure beats the 90.00 alternative
wrk2surf-thanks. There is another post floating around today with similar problems and your suggested fix. One update-I already posted this in the other thread. Their mechanic suggests that the oil mineral oil was shot and that it needs to be changed 2 x a year. He went on to say that if the o ring was beat, then there would be a immediate failure after the system was recharged and bled. So, I'll give it a try. Thanks for your input.
I'm having same clutch problems on my 03 640. Does anyone know of a thead that shows or describes someone fixing this problem. I'm ready to have a go at it myself but Pictures always help. Thanks
http://www.advrider.com/forums/showthread.php?t=564620 http://www.advrider.com/forums/showthread.php?t=464845
Left Oklahoma with normal function and woke up in Waterton Springs Camp ground north of Glacier with no clutch. Got going downhill and slipped it into gear after starting engine in neutral and limped to Pincher Creek, AB where the local Yamaha mechanic said "none of my KTM buddies ever ride out of here without an extra clutch rebuild kit". He slipped an o-ring in behind one of the seals and bled the system. Clutch returned After an overnite back to Great Falls, Montana, where Steve and Jeanie who own the KTM dealership met me at 9:30pm to sell me a rebuild kit, I returned to Pincher and took off for Alaska only to be plagued again by the clutch going out about 100K above Jasper. Put the kit in the clutch master cylinder, bled it and took off again but by the time I reached Whitehorse, YT it was gone again. The recurring theme here is bleed the system and it works, partially bleed it and it works for awhile. In Whitehorse it was well bled and the clutch has held until reaching the top of Tehneta Pass about 140 miles N. of Anchorage where the bike lost its electrics and required towing to Anchorage. Thanks to all who have contributed the good info in the forum. I'm troubleshooting both the clutch and electrics while warm and dry here in the city before heading back out on the trail home. At this point I don't know what to tell people who want to wander off into the hinderlands of N. America on a KTM without extensive mechanical support and knowledge. Perhaps ride a BMW. The princess, as my buddy calls the 640A, is a great ride but is disappointing for reliability. Read all you can and absorb the knowledge before venturing out and keep critical parts and tools with you.
is the wall worn from the o-ring on the piston??.. are you leaking from the lever plunger?? if those two are good and you bleed it should last at least 2 yrs of hard riding... trust me..
I think having mechanical knowledge and carrying common wear parts is a good idea with whatever brand of bike you take to the wilds.... I've ridden with groups that have many flavours of bikes and my 640 has had few issues when compared to the other brands on the ride... The secret is having a pre-big trip checklist that has you going over everything... This thread relates to a common electrical problem:http://www.advrider.com/forums/showthread.php?t=169958
An old thread, once again... I seem to be losing about a reservoir's full of clutch fluid (rendering the clutch slowly inoperable) once per about 7000 km's. It is obviously not a huge problem, as it does not occur very often, but still an inconvenience at the least. When the clutch goes out at the middle of a swamp or other "soft" place, it really asks for some creativity to get the bike back onto hard ground again under its own power. Also, last winter, when I changed the clutch fluids and the slave cylinder o-ring, I encountered the problem described in this thread. For the life of me, I cannot find any other leaks in the system, and even this "weeping" from the master cylinder cover ceased after a while. Might very well be that I overfilled the reservoir in the first place. Once this excess was bled out naturally, the leaks stopped (?). For now, I've decided to always carry a bottle of Magura Blood with me on the bike, but I am interested in hearing if anyone else has had these same troubles, and especially if anyone has found the final solution for these tribulations. Cheers, Tseta
Fellow ADV riders with 640 ADV bikes. The O ring size is as follows JIS size in S Series of O rings Part # S 25 ID 24.0 mm cross section 2mm of nitrile rubber. Clean the area up nicely before you attack the following. Don't break the chain, remove the drive sprocket & sit it just off the drive spline to give you the room to remove the slave cylinder casting. Once the 3 M6 allen head screws are removed wiggle the casting out from the cables & flexible oil lines. The piston can be removed from the casting with pliers or by blowing out with comressed air. Inspect cylinder bore for wear, mine after 40,000km had none & is in poifect condition. If worn it'll be best to replace the casting, sorry. Remove old O ring, clean up piston, renew O ring & place back into cylinder with spring & a little mineral oil. Clean up engine casing, gasket & replace. Bleed the system by filling the slave cylinder with oil, replacing the banjo with annealed copper washers. Next bleed from the bottom by forcing the oil into the bleed nipple & up to the master cylinder. KTM are selling little plastic bottles of oil these days. Use the bottle with a 25mm piece of clear 5mm pvc tube over the nipple & onto the tapered nozzle of the bottle & squeeze the bottle with the nipple open. Once you've got some fluid coming out into the master cylinder, top up the reservoir, leave it a while, have a beer, come back, lean the bike over to the right to get the flex line pointing up, lightly tweak the clutch lever & this will allow any air to pop out in to the master cylinder & that should be it. If you've used brake fluid in the system more than likely you'll have to renew the master cylinder seals at KTM cost otherwise just replacing the slave piston O ring should do the trick. Cheers Brochureman.
I'm stuck here: my flexible oil lines and such are too tight. I can't get the slave cylinder casing out from beneath them. Any thoughts? Maybe the line and such shouldn't be this tight, but I"m thinking I'll have to lay the bike on its port-side and take off the oil filter cover so I can proceed with the slave piston o-ring replacement. Fresh oil change... I don't want to loose too much of it.
Hi Meat, your probably OK to just remove the cover and have minimal oil loss... What is in the filter chamber will leak out but the rest should be held at bay by the oil pump... If your oil line banjo bolts are frozen, try using a little heat on the cover around where the banjo threads into it...
Thanks gunner, I don't mind letting the bike take a rest so I laid her over; still lost some oil. Replaced the o-ring, and bled the system according to Oberon's method (worked very well). Seems to be good. Wondering how much trust I should put on the repair; I am off to Death Valley for a week soon...
With a new O-ring in it your slave should be good for a while... Have you also rebuilt the master anytime recently? If not I would recommend you do or at least carry the parts with you on the ride as they are easy to change in the field in case the lever gets spongy...
