Clean the oil jet for clutch lubrication.

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by KTRMN8R, Jan 14, 2007.

  1. cpmodem

    cpmodem Orange Caveman

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    The clutch is lubricated with oil from the same passage as the transmission. After the crankshaft, pistons, rods, camchain, cams, and transmission gears and bearings are lubed, what's left goes to the interior of the wet clutch via the clutch oil restriction jet and through the pushrod passage to the interior of the clutch inner hub. Some of the oil in the inner hub is used to lubricate the sliding surfaces of the clutch booster. The remaining oil then flows through holes in the inner hub to lubricate the friction disks and the sliding surfaces of the clutch. After which the oil is flung out of the clutch to drain into the oil sump for pickup and return to the oil tank by the oil scavenger pump.

    BTW, the clutch oil jet is listed in the "Scheduled Maintenance" to be removed and cleaned every 15,000 km. Doing this every oil change is an even better idea, especially if your clutch gets hard use.
    #81
  2. Moraflex

    Moraflex Banned

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    Thanks for the explanation. I'll check that jet next oil change. Only got 3800 miles on the beast thus far.
    #82
  3. emelgee

    emelgee Been here awhile

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    Don't drill out the jet too big:huh

    Just finished off a service and decided to check the clutch for wear - all within spec, so I pulled the jet out to take a look.
    The jet appeared to be blocked, and having read somewhere that the Dakar bikes had larger jets for better lubrication I thought I'd drill it out to 1mm and see what happened.
    The result - it's impossible to engage neutral at a standstill with the enginee running. After re-reading this thread I noticed that K2M made the same mistake.
    With the engine off, bike in gear and clutch pulled the bike rolls back and forth easily enough, so the clutch is disengaging fully - my guess is that too much oil on the plates is causing a bit of 'drag' in the clutch.

    I'll be on the phone next week to get another 0.3mm jet, and I'll leave it at that size.

    On a sidenote 5W fork oil seems to work well in the hydraulic clutch - I usually use specific clutch oil, but didn't have any on the shelf.
    #83
  4. cpmodem

    cpmodem Orange Caveman

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    That specific issue is discussed in the HOW :deal

    "The oil jet selected by the engineers at Mattighofen for the 950/990 Adventure is a compromise based on the assumption that the bike will be used mainly on the street and gravel/dirt roads. If the bike is used hard (ie: slipping the clutch to manuver tight trails or get through rough terrain or deep sand, or racing conditions) the clutch jet size should be increased (.40 - .50mm) and possibly some modifications to the inner clutch hub made (AKA the Feliciani Mods) to accomodate the extra abuse. Don't go too big; unless you're racing the bike, the 1.0 mm size Feliciani talks about for desert racing is too big for non-racing use. Be advised that some "streetability" may be compromised even with the .40- .50mm sizes (ie: hard to find neutral, clunky shifting at slow speed, etc.). Best to start small and work your way up. Have a spare .030mm so you can go back down when you get too big."
    Sorry :knary
    #84
  5. emelgee

    emelgee Been here awhile

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    You live and learn, as the saying goes.:D
    As soon as I'd drilled it out I thought "Mmmm, that might be a bit big!".
    When I had the clutch cover off there was a coating of oil cooked onto the inner cover and basket - it looks like it's been getting a bit hot in low speed tricky stuff, so I thought a bit more oil flow might help.
    Looks like I'll stick to the stock size and maybe get a 0.50mm for extended offroad use.
    #85
  6. cpmodem

    cpmodem Orange Caveman

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    Well at least it may save someone else the same experience. Thanks for the heads up.
    :freaky
    #86
  7. 1stiski

    1stiski Ride that nasty thing

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    Oh the wonderful things you learn here !!! Always a pleasure.:clap
    #87
  8. MrH

    MrH Been here awhile

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    Like others above, I've an 03 model., and after reading this thread had a look at the Oil Reduction Jet the other day and - mine's never been done either, there's a brass plug, no jet.

    Now on the one hand I'm pissed off that the dealer I bought it from (Premier in Didcot) told me all required updates had been done, but on the other there's nothing noticeably wrong with the clutch after 32k miles, so I can't exactly complain, can I?

    The Repair Manual I've got is the 03 one, and the lubrication diagram in there doesn't show any oil going to the clutch at all, or the pushrod, just 'Another oil duct leads to the oil line that lubricates the transmission gears.'

    I find it hard to believe that the clutch itself gets all it's oil through a 0.3mm hole? If I've still got the brass plug in instead of the jet, does that mean my clutch doesn't get any oil? So what is this jet supposed to fix?
    #88
  9. emelgee

    emelgee Been here awhile

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    I was thinking the same. If the early bikes had plugs rather than jets then oil must be reaching the clutch by another route....
    The other question is why would they make a provision for running an oil jet and then install a blank plug, and then change their minds and put a 0.30 jet in there??

    Anyway, it looks like the KTM OEM jet is the same type as the Dellorto 6413. A quick ebay search pulls up a seller offering sizes from 53 upto 172 at £2.99 each.
    #89
  10. cpmodem

    cpmodem Orange Caveman

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    The clutch gets lubed with oil from the transmission via the mainshaft and countershaft roller bearings and to a degree from oil thrown off the counter balancer gear and pinion gear. The clutch also runs in whatever oil is pooled in the sump.

    Originally, apparently it was decided that that was enough oil for the clutch for its intended use. After the first season of racing, it was obvious that it was not enough for racing conditions. The Rallye bikes were having clutch problems. Amongst other things, Feliciani (Meoni's mech) and others were putting larger and larger jets inplace of the plug to help lube the clutch better from the inside (via the pushrod passage).

    In July of 2003, KTM started installing a small jet .30mm. This was supposed to be retrofitted to all previous models in a Tech Bulletin (0309/38/01-E) issued in September of that year

    The engineers were reluctant to install an oil jet at first, but they allowed for one in the design. As stated earlier, too much oil to the clutch causes problems also.
    #90
  11. YOGOI

    YOGOI Prick

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    BRILLANT !!!!!!!!
    #91
  12. MrH

    MrH Been here awhile

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    Thanks for that CP, that's a good answer! Don't know your background, but your answers often have an authority that makes me wonder if you have some inside info?

    In the pic I've got, the only oil feed to the gearbox supplies a line that appears to have nozzles which spray directly onto the gears, there's no sign of an oil feed to the bearings, or anywhere else so I'd guessed it wasn't showing the whole story.

    I'm already less than pleased with Premier, I suppose I'm going to have to go back there and try and get them to give me an oil jet, maybe I'll quote Tech Bulletin (0309/38/01-E) at them! Makes me wonder what else hasn't been done though. :huh
    #92
  13. DockingPilot

    DockingPilot Hooked Up and Hard Over

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    I have a Dellorto #70 oil jet installed after my booster smoked itself.
    :thumb

    Shifts like butta........
    #93
  14. emelgee

    emelgee Been here awhile

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    Just replaced my 1mm drilled jet with the Dellorto size 50. Normal service resumed:D
    #94
  15. uk_mouse

    uk_mouse Aquatic adventurer

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    I think I've posted this before, but just to add to the knowledge base, I'm using a 0.75mm jet, it's sometimes tricky to get into neutral, but a good blip of the throttle usually sorts it out.

    Remember oil flow will be proprotional to the area of the hole in the jet, which increases with the square of the radius. Therefore a 0.75 jet will flow about 6 times as much oil as a 0.30. A 1mm jet will flow 11 times the oil of a 0.30.

    (I'm assuming oil flow is linearly proportional to hole area, which it might not be, but you get the idea).
    #95
  16. DockingPilot

    DockingPilot Hooked Up and Hard Over

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    Here's what I just did.
    I bought a set of acetoline torch tip cleaners. Find the right size from the kit and just simply run it through the jet orfice. No need to remove it now.
    Works like a charm and it's quick.
    #96
  17. Moraflex

    Moraflex Banned

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    I was up on twisties this weekend and the bike only has 4008 miles on it. At the end of the 120 mile ride I noticed the up shifting took on a slightly different feel, in that it took two clicks to upshift one gear. Normally it's only one click. I took out the jet and sure enough, clogged! Blowing into the jet did not unclog it so I needed something else. I didn't happen to have a .010" wire laying around, but I did have two .005" wires which I twisted into a pair and that unclogged the hole. Took it for a test ride and it shifts in one click.

    In the future, I will buy a High "E" .008" or .010" guitar string to poke out the hole without removing the jet. Turns it into a 10 minute job to be preformed every other month.

    Why a guitar string you ask? Spring steel, wont break off and available everywhere.
    #97
  18. Nightstalker

    Nightstalker YO BUDDYPAL!

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    Guitar string is a great idea!!

    I'm about due for a new set! Now I have some purpose for the old strings.

    #98
  19. aurel

    aurel Cheese&Wine!

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    I tried to get the jet out that way without success... :cry

    I was not able to put enough force vertically on the screw so the screwer was sliding out of the head screw everytime before it starts turning...

    I'll try with a hot engine :lurk But what a pain to access that screw, I'll try to make a special tool to make the job easier...
    #99
  20. cpmodem

    cpmodem Orange Caveman

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    I've found precision hollow ground screwdirvers of the type gunsmiths use to be the best for the soft material of jets. They come in all lengths. There will be a slot driver ground to precicely the right shape. In the case of the oil jet, it is a #4.

    [​IMG]