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Snowman

KTM Hydraulic Clutch Issues

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Dear Forum Members and Tech Gurus.  I have a 2006 450 exe-f which I have had for 2 years.  All has been fantastic until my last Dirtriderz ride at Mt Dissa.  I had a bit off an issue with Hamburgers with the KTM going up and over at some stage.  Finally got to the top and the clutch was dragging very significantly and I could not come to a standstill without stalling.  Struggled on for a bit before retiring for the day.

I assumed it was just some air in the line so bought some OEM hydraulic fluid, drained the system and reverse bled the new oil in.  Some improvement with able to hold first with clutch in with a little throttle once the bike is warm.  But still nothing like it was.  I have rested the bike with the master cylinder raised to bleed out any bubbles.  No further improvement.  

I have bled it again with no further improvement.

Now I have an odd behaviour where with the lever adjustment in the clutch really drags.  However if I wind it out the clutch will drag, engage a little, then disengage and reengage again when the lever is almost right out.  So feels like a two stage clutch where if you start to pull it in the clutch disengages then reengages just before the stop and then disengages but drags significantly. 

Dont know if the issue was caused by the flipping the bike or slipping the clutch up Hamburgers.   Bike has done 180hrs but not sure what the service life was before I bought it.  Have not changed oils or anything else so I am stumped.

Planning to take it in to be looked at as beyond my knowledge know but wanted to check if anyone had any ideas or advice before I go any further.

Many thanks

 

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Without knowing how much the clutch was abused it’s hard to say for sure but if you got it real hot you may have warped the steel plates. Since you seem fairly certain it happened at that moment and it won’t fully release that’s my guess.

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I'm no guru on KTM's and the KTM clutches are a bit, well, odd.

Caught air in the line does make it's way out with use so it's more forgiving than air in the brake lines. If you've ridden it a bit and the levels not low it's probably not your root cause but no harm in giving it another bleed.

After overheating the fluid can boil if it's old and has drawn a bit of moisture into it over time.. A fair bit of the old fluid stays in the bore in the crankcase when you flush it from the bleeder up to the master cylinder. If it's a problem cold it's probably not your root cause but no harm in giving it another flush again.

There may be leakage at the slave cylinder end - this could be the cause but it would take a bit of use to show up and you'd see a lowering of the fluid level in the master cylinder. If this is the case it needs a service. Btw you won't see a fluid leak because it's likely the fluid will be pushed into the gearbox.

The funny action sounds like its sticking in the slave cylinder end (the crankcase bore end).

The clutch plates are very thin and I don't think there's much travel in the system. In doesn't take much wear in the plates to get the pushrod in a position that the slave end doesn't like and starts sticking. Sounds to me like your plate stack is now under the service limit. It's really easy to pop the clutch out and measure it; doesn't need a lot of technical knowhow and i'm sure there'll be youtube videos to show it. Once out measure the full pack width (metal and fibre plates) and check it against the spec (not sure if the KTM owners manual will show the spec but it will be in the workshop manual - your local dealer may be able to advise it).

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Thanks everyone for the quick response.

Have replaced clutch oil a couple of times and do not seem to be losing level in the master cylinder but have not riden much since this issue started (just around property with kids) so may not enough to notice the fluid lose if a leak in the slave.

Think might just have been the end of service life so will look at this and see how I go.

Thanks all.

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Once last considered before you tear into it. Some ktm models use mineral oil and others DOT 4/5 be sure your using the right juice. Good luck.

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I cleaned my 2000 400 exc last year, i've probably done a total of 7,500 klm & i't started playing up, i totally pulled the master cylinder apart & it had some slimy looking oil in the master cylinder, hose etc . After some brake cleaner, toothbrush & air action all was spotless & i reassembled it, Anthony @ Proline suggested i buy a litre of Gulf Western Hydraulic jack mineral oil for about $15 works a treat.

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4 hours ago, eagle said:

I cleaned my 2000 400 exc last year, i've probably done a total of 7,500 klm & i't started playing up, i totally pulled the master cylinder apart & it had some slimy looking oil in the master cylinder, hose etc . After some brake cleaner, toothbrush & air action all was spotless & i reassembled it, Anthony @ Proline suggested i buy a litre of Gulf Western Hydraulic jack mineral oil for about $15 works a treat.

Was that it’s first wash ? :D

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OK........have ordered a new set of plates and will test my mechanical skills replacing as well as looking at master cylinder.  If I this does not work then I will hand it over to the professionals.  What could possibly go wrong.

Thanks for the advice from the forum members.

 

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4 hours ago, Snowman said:
OK........have ordered a new set of plates and will test my mechanical skills replacing as well as looking at master cylinder.  If I this does not work then I will hand it over to the professionals.  What could possibly go wrong.
Thanks for the advice from the forum members.
 

It is a relatively easy process. One tip I will give is to get a piece of cardboard and a texta and roughly draw the shape of the clutch cover and mark where all the bolts go. As you remove the bolts put them through the marks then when putting back together all bolts go back in the right holes (some may be longer for various reasons, I do this for all covers to help when I'm waiting for parts to arrive)

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Make sure you soak the fibre plates in oil overnight, they need to absorb oil through them otherwise you'll burn them out.

When you put the new ones in be careful with the metal plates. The first (and sometimes last one as well) are thinner and there may be spring washer as well but I'm not sure about KTM's). These ones are there so the first and last fibre plates run against steel and not the aluminium surfaces of the inner basket and outer pressure plate. If you don't have a manual pull the old plates out one at a time and measure them. On later models the first and last are around 1mm thick and the others are 1.6mm (from memory) and you can tell just by feel and look but you can check them with a ruler (or vernier or micrometer if you've got one). If you get stuck feel free to pop us a pm and I'll give you a run down over the phone).

It sounds complicated but if you go step by step it's pretty straightforward and obvious after you've had the heads up.

There's Engine parts manuals on KTM.com for download (I couldn't check if it covers your model because their site isn't working for me at the moment) If it's available and you can get in and download at least the engine manual (it's the same exploded view parts manual your dealer looks up spare parts numbers on) it's really handy. If you look at the clutch parts the plates that are a different size will have a different part No and should also have the thickness in the part number and will show where they go in the pack in the exploded view.

Check this site as well, there's a downloadable (free) service manual listed for an SX/EXC/XC (don't know if an EXE is one of these though)

https://kristofsx.com/

2000-2007 250/400/450/525 SX/EXC/XC Service Repair Manual

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Just looked up the parts list for a 2006 450 EXC (there's no EXE-F?) online http://www.ktmonlineparts.com.au/partFinder/fiche/ktm/2006/450-exc-racing/clutch#ficheZone

First 2 metal plate and last 2 metal plates are 1mm thick, the middles 4 are 1.4mm

Also shows Loctite on the bolts holding the springs (never seen or done this on Jap bikes or my 350SXF though). Still, KTM's fall apart so probably not a bad idea.

With what your doing you'll only be undoing the 6 spring bolts and sliding out the pressure/metal/fibre plates so hopefully you'll get a idea for how simple to do it is.

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Thanks BearMX for the great resources and advice.  I have watched a couple of YouTube videos and along with the manuals and parts lists above.  Looks fairly straight forward however in the videos it showed a set of rubber dampers inside the clutch pack but the parts list / exploded diagram does not show these for my bike.  I therefore assume that these are a more recent addition and not something I need to worry about.

Also great advice MrNoodle on the cardboard template as I saw that all the bolts are different lengths on one of the videos.

Will let you know how I go next weekend.

Cheers 

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The later models the 500 for sure has the dampers. Pretty sure your RFS motor does not.

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Just looking @ parts on Munns site on ktmtalk.com, & they came in on the 2002 model when the clutch changed a bit, & they had 2 sizes of metal plate also.

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OK.........while I wait for my new clutch pack to show up I decided to strip down the master cylinder and clean it all out as per Eagles suggestion above.  Stripped it all down and cleaned it with carby cleaner before drying out and putting back together.  Once reverse bled and pumping the clutch lever to ensure no air in the line it seemed better the first change but then seemed to get worse again.  Is better than it was but not like it was. before the Hamburger indecent.

Worried there might be a leak somewhere as if pumping the clutch it is better but then seems to get worse again.

Have new clutch pack hopefully arriving today and picked up a set of half washers as read that if these get pressed they will cause clutch drag.  Hard to believe that a simple washer cut in half would cost $14. Guess I should be happy that I can get parts for a 12 year old bike.

will update next week once new clutch and half washer installed.

Cheers

 

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Clutch pack delayed until next week and then away for a bit so won't get to swap this out for a couple of weeks.  I had a bit more of a play with the bike and clutch today and some very weird behaviour.  I started the bike from cold popped it into gear and all was good as gold.  Moved the bike forward 10 meters and pulled clutch in and all good.  However while sitting there with the clutch in suddenly the clutch gripped and significant clutch drag.  I stopped the bike, pumped the clutch and started again.  Same thing happened.  All good and then after 10 seconds the clutch suddenly started to drag.  I replicated this 3 or 4 times so seems there is a loss of pressure somewhere.  So may be a leaking slave cylinder into the gearbox as flagged by Bear MX early in the piece as can not see any leaks at the master.

I assume this is simply an o-ring replacement senario.

Again thanks everyone for the advice and support.  Need to fix this so I can get out riding again. 

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Clutch pack delayed until next week and then away for a bit so won't get to swap this out for a couple of weeks.  I had a bit more of a play with the bike and clutch today and some very weird behaviour.  I started the bike from cold popped it into gear and all was good as gold.  Moved the bike forward 10 meters and pulled clutch in and all good.  However while sitting there with the clutch in suddenly the clutch gripped and significant clutch drag.  I stopped the bike, pumped the clutch and started again.  Same thing happened.  All good and then after 10 seconds the clutch suddenly started to drag.  I replicated this 3 or 4 times so seems there is a loss of pressure somewhere.  So may be a leaking slave cylinder into the gearbox as flagged by Bear MX early in the piece as can not see any leaks at the master.

I assume this is simply an o-ring replacement senario.

Again thanks everyone for the advice and support.  Need to fix this so I can get out riding again. 

Snow man, that’s why I asked if the fluid in the reservoir has gone down. It won’t necessarily leak because it goes inside the motor.

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I don't like the KTM hydraulic clutch design. The crap that collects at the slave cylinder has nowhere to go. It stays there when you flush at the bleeder. Not to mention that moisture / water will collect there (especially if mineral oil is being used). Plus there's limited travel and when the clutch is worn it starts disengaging the clutch even though the plates still have a bit of life in them (when you get your new clutch keep an old 1mm steel plate - it can be used in an emergency to pack out a worn pack on the trail - I've seen a 690 that had one cable tied to the rear of the radiator)

On the positive side it is as basic as it gets - a cover with a gasket and a big diameter piston with an O ring piston seal. If you decide to pop it off for a clean at some point it should be easy to do and if the gasket doesn't tear you might be able to reuse it.

Don't wash the o ring in solvent or degreaser - wash with warm soapy water, towel dry and give it a bit of time to air dry as well (hair dryer on low heat setting will do it quick), inspect for any tears or cracks. Then soak it in oil for a while before reassembly. (For brake fluid system soak in brake fluid. For mineral oil systems I use auto trans oil for o rings, the hydraulic jack oil is good too).

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It is a relatively easy process. One tip I will give is to get a piece of cardboard and a texta and roughly draw the shape of the clutch cover and mark where all the bolts go. As you remove the bolts put them through the marks then when putting back together all bolts go back in the right holes (some may be longer for various reasons, I do this for all covers to help when I'm waiting for parts to arrive)
Here's one I prepared earlierDSC_6263.jpeg
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If fluid level is dropping in M/cyl resevoir and no sign of leak at m/cyl then suspect slave cyl is u/s. If level is not dropping then suspect m/cyl is by passing, m/cyl u/s. If clutch was at fault being mechanical I would expect consistant faulty operation. 

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