Clutch, transmission problem KTM 990 ADV

Discussion in 'KTM 950/990' started by breitsmeister, Sep 4, 2019.

  1. breitsmeister

    breitsmeister Adventurer

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    Hello,

    I have an KTM 990 ADV with 56000kms.

    The problem with the bike is from neutral to first or second it feels like the clutch is engaged for half a second, while i'm pulling in the clutch lever.
    Im pretty sure that's not normal, because the clutch should disengage completely when working correctly.

    I've made a video about it:

    https://gofile.io/?c=bZXT2O (wait for the video to load)

    I did some research and checked the following things.
    Oil jet is open. (original one I think)
    Clutch basket has smooth surfaces so that's in good condition.
    Clutch plates are in specification.
    Replaced the master cylinder (Magura 10,5mm bore) (was leaking)
    Replaced the clutch slave cylinder (oberin) (was also leaking)
    Clutch oil change LHM+ mineral oil
    Belleville spring steel plate had a score so I've changed it with another good plate (didn't help)

    I think it could be a couple of things:
    Warped steel plates of the clutch, so the clutch will never completely disengage when there is no gap between the steel plates and the clutch plates, when you pull the lever in.
    Worn clutch booster pack, so when it's worn it creates always a bit pressure on the clutch plates even when you pull the lever in.

    I don't think it's the transmission itself because it's a problem about the disengaging of the clutch.
    I know the clutch is a weak point of the 990 LC8 but there must be an issue with my bike because i'm sure the clutch won't act like this when you buy the bike new!

    What do you think?


    greetings,

    breitsmeister
    #1
  2. breitsmeister

    breitsmeister Adventurer

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  3. ettienne.scheepe

    ettienne.scheepe Adventurer

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    Have you checked the clutch springs that sits behind the bolts that go through the plates they have a spec they need to be in.
    #3
  4. breitsmeister

    breitsmeister Adventurer

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    hello, yes I've checked and they are in spec.
    #4
  5. ettienne.scheepe

    ettienne.scheepe Adventurer

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    It sounds like the clutch is not engaging fully.
    Is your slave installed correctly with the ball bearing and such.

    Also make sure it is sitting flush on the engine had an issue with mine not being flush.
    #5
  6. breitsmeister

    breitsmeister Adventurer

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    Hi, the clutch never slips when opening full throttle, so it should be engaged properly.

    Took the clutch booster apart.
    I can definitely see wear on the inner part.

    Question can you weld it up and vile it back to its original shape? Or is it hardened steel?
    Does somebody has a spare one?

    Attached Files:

    #6
  7. ettienne.scheepe

    ettienne.scheepe Adventurer

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    Yea that is not ideal they aren’t cheap either.
    Think they are like almost 400$ R4000 in south african currency.
    #7
  8. tinwelp

    tinwelp Professional Idiot

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    Odd. I've not watched your videos (I've too little patience to wait for it to load with my super crappy bandwidth and the antiquated GoFile data packaging), but tell me if I understand your problem correctly: you pull the clutch lever to disengage the clutch, but something suggests it doesn't disengaged immediately. Is that it?

    First and most obvious question is when does this happen? Your posting is well written and pretty comprehensive by the standards of many forums, so I expect you're not doing this test with the bike sitting on the centre stand with the wheel already spinning before trying to shift out of neutral. What about if the bike is hot, cold, left overnight, only after using the side stand... some situational qualification may help.

    If I'm assuming correctly that that you have the same issue with the wheels on terra firma, it sounds like either the clutch plates are sticking together for some reason, or there's something compressible between the lever and the clutch pressure plate. In the first category is things like wrong oil specification or severely degraded; blocked or incorrectly sized clutch jet; warped clutch plates; notched clutch basket. You've mentioned nothing of your oil, but most of the others you suggest are ok (bit confused with the clutch plates though... in spec, but you suspect may be warped???). In the second category, almost every conceivable fault would manifest a bigger issue like an inability to release the clutch at all. However, what if you still have a small quantity of trapped air in the line, maser or slave? It would behave a little like a spring. It's a long shot, but maybe worth re-bleeding with a different technique?

    As for the clutch booster, I believe it's unlikely to be part of your problem. To eliminate it from consideration though, just file or grind the gouges out to make a uniform and smooth surface. It should be surface hardened, but I think you're past that stage and it should file OK! It really needs to be replaced, but mine was worse than that the last time I looked at the clutch, which must be at least 20000km ago by now, and I've no issues as you describe.

    Good luck.

    Cheers... Paul
    #8
  9. breitsmeister

    breitsmeister Adventurer

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    Hi,
    To answer your questions:
    When does it happen? It happens always, with cold or hot engine.
    It's always the same behaviour, the problems occurs with the wheels on the ground and on the center stand.
    I bled the hydraulic clutch system with a syringe on the slave cylinder, so all the air is going away on top.
    The steel and clutch plates thickness are in specification but they can still be warped, that was what I meant.

    I've filed down the inner clutch booster, and it helped.
    This will be a temporary fix so I definitely need to buy a new one in the future, or maybe rekluse
    #9
  10. gearheadE30

    gearheadE30 @LC8Adventures Supporter

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    Clutch booster looking like yours generally causes rattles and maybe some nonlinear engagement, but not as severe as what you describe. It really sounds more like a loose or notched clutch basket, or a loose clutch basket nut, but you would have seen those when you were in there. The belleville spring can also cause the same symptoms.

    My 90k mile 950 has had an inconsistently draggy clutch for thousands of miles now. I haven't been able to resolve it so I just deal with it. However, the clutch is far from a "weak point" on these bikes. Even competing off road on my 950, I'm still on the original clutch after all those miles.
    #10
  11. Michhub

    Michhub Major Medical Supporter

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    Nobody mentioned the push rod...well documented issue on older bikes...
    I have 60K on my 990, having replaced the slave (Oberon) and up sized the Oil Jet its all stock still...
    #11
  12. breitsmeister

    breitsmeister Adventurer

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    #12
  13. tinwelp

    tinwelp Professional Idiot

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    Ouch! That's almost as expensive as the official KTM part...

    Thanks for your answers, I now completely understand. If I remember well, the manual says something about the tolerable warp of the steel plates... so that's part of the specification. Probably worth measuring to eliminate it from your quest for a solution.

    What about your oil? Is it fresh and correct spec? How about trying a different size clutch oil jet? If you get a response (better or worse), at least you'll know it's oil related.

    I take it your clutch lever action is firm and without any suggestions of air? Sorry to ask again, but I know a lot of people have experienced issues bleeding the clutch even after replacing stuff. If you're confident in your work and it seems firm, forget it. I much prefer the 'bottom up' bleeding approach and have never experienced problems with the technique providing both cylinders were filled before assembling anything. Sounds like you're methodical enough to get this right though.

    Last thought, have you tried anything other than LHM+ ? This is tiny bit more viscous compared to the Magura recommended stuff, or something like baby oil. Although I think it'll just change the feel at the lever rather than address your problem, it may be worth trying to see if the problem responds in any way.

    Cheers... Paul
    #13
  14. breitsmeister

    breitsmeister Adventurer

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    Hi,
    Can't find any specifiation about max. warpage of the discs in the repair manual.
    Clutch lever action is firm.
    Haven't tried any other hydraulic fluid, it's mineral oil, I don't think any lesser or larger viscosity oil would help.
    I've always used 10w50 Motorex powersynt engine oil, the oil level is good.
    Changed it 6000km's ago.
    Pushrod's were a problem on the 950s I have read, I've a 990 with the black pushrod and they seem to be fine.

    Could try a bigger oil jet.
    Ordered a new clutch booster, so let's see how that goes.
    #14
  15. DirtyADV

    DirtyADV Long timer

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    Bigger jet will only make any drag worse. More oil equals more friction when disengaged.

    Rather go with a plug like some of the early 950 had.

    All i have tried creeps a little and if you are not firm with the gear lever will cause some grinding sounds.

    /Johan
    #15
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  16. Michhub

    Michhub Major Medical Supporter

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    I mentioned the pushrod as its considered a wear item, your scrutinizing everything else....

    [​IMG]
    #16
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  17. breitsmeister

    breitsmeister Adventurer

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    Hi,
    Going to remove the pushrod and inspect it once I can replace the clutchbooster.
    #17
  18. breitsmeister

    breitsmeister Adventurer

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    Hi,

    Received the booster yesterday, i've fitted it now.
    Pushrod looks fine, no excessive wear.
    I'm a bit surprised because it didn't even help one bit!
    There goes 270 euros...

    Oh I just want it fixed..
    So I went on to investigate and the first thing I did next was removing the clutch slave cylinder.
    I saw it was a bit dirty from the chain grease and I saw some green oil. (LHM+ is also green, I've used that as the hydraulic fluid)
    The clutch slave cylinder might be leaking!
    I bought it last year July 2018, i'm going to contact Oberon for warranty..
    Yes I know i've should have checked this earlier, i've had this clutch problem for months and I want it fixed now, you see.

    On the picture it looks like engine oil but in reality it is green oil.

    Attached Files:

    #18
  19. ettienne.scheepe

    ettienne.scheepe Adventurer

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    Mine does the same thing but the oil does not leak out.
    And it works fine so not sure if that is tour issue but best to get info from oberon.

    I would also recommend getting the billet part that goes in between the slave and the engine case as well.
    #19
  20. DirtyADV

    DirtyADV Long timer

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    Any chance clutch lever been pulled while slave was off the bike?

    Think the Oberon has a bleed port allowing excess oil to leak if piston goes out to far rather then damage things like with original unit.

    Or just some oil spill seeped in there while bleeding?

    Sure it might be faulty but never heard of a bad Oberon before.

    /Johan
    #20
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