LC4 640 starter clutch fix

Discussion in 'Thumpers' started by losiu, Apr 17, 2007.

  1. dustjunkie

    dustjunkie Got Stick Meat?

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    That was my first idea, but couldn't find any on short notice... Good Luck!

    Jake
    #21
  2. losiu

    losiu wheelie addict

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    Sorry for not replying earlier but I thought you got enough info on the puller. The one I used was made just to fit the thread and it doesn't even look like the little, tiny thing that KTM uses.

    The beer was actually German, but I'd go for Chech if I had that choice.
    You can check out the proper Polish beer right here.
    http://www.youtube.com/watch?v=YAVtfHa_HGw

    Good luck. Post the results (of both drinking and fixing the bike)

    L.

    PS. Rapiti, I think you're needed on the wheelie thread...
    #22
  3. rapiti

    rapiti IOR Veteran

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    Cheap that I am, I bought a puller set from HF for $6.99, and scrounged up two 6mm bolts from old bicycle stems. I have been very buy with other stuff, so I simply bought the sprague clutch from Munn's. With the $60plus in the sprague clutch, I ma going to have to drink some to equal Losiu's beer/parts ratio!

    I will tackle this project when the parts arrive...:freaky

    #23
  4. johan

    johan Been here awhile

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    This sound you guys were experiencing when the spring turned out to be the culprit, did it

    1. Sound bad continuously when you pressed the starter button and cranked the engine

    or

    2. Sound bad when the motor didn't fire after you had let go of the button
    #24
  5. losiu

    losiu wheelie addict

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    Hey Johan,

    Not sure about point two.
    Maybe somebody who has or had the problem couldn confirm that...

    My problem was that the bike did not want to start at all. Instead, the engine was making the noise described in the first post. Too bad I didn't think about recording the sound before starting the "how to" thread.

    Sometimes, if I was lucky, the engine started, but generally it just made a lot of noise and it didn't want to turn over. It always starded when I kicked it, though.

    L.
    #25
  6. Beez

    Beez Given to fly

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    3. all of the above.

    It made the sound when the starter was engaged and there was a slight carry over after the button was released. Like a kaa-chuuuugh. :uhoh That's what I remember at least.
    #26
  7. Primo

    Primo Lonely Rider

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    Hi!

    I have the exact same problem - starter clutch makes evil and scary noises.I decided to try and fix the damn thing.I drained the oil (i was planning an oil change anyway), screwed off the sideplate and also the big nut holding the flywheel and took the flywheel puller which was ordered according to parts catalogue number ( 26mm x 1mm, '88 - to present 400-620cc models was written on the package ).So heres the catch - THE SHIT WON'T FIT.So i measure the bolt where the puller has to go - 33mm and i still don't know the step of the screw.
    I have 640 '00 model.

    If anyone knows the measurements, please don't be shy:wink:

    Regards,
    Alan
    #27
  8. mikeegee

    mikeegee Been here awhile

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    It's been about a year since I did mine, and I thought I would be smart and order a flywheel puller from someplace - it didn't fit.

    I finally got pissed and used a 3-arm gear puller that I got from HF for maybe $10. I couldn't twist it off with a breaker bar, so I got pissed again and used my 3/8" air gun and whadda ya know, it came off.

    Now when I say came off, I'm being nice. It makes a very nice, and resounding "bang" noise, and comes off with some some speed. Make sure you have a nice place for it to land other than your shins or your feet.

    Then I went and got pissed.
    #28
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  9. mikeegee

    mikeegee Been here awhile

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    Oh yeah, and mine's a 2000 as well.
    #29
  10. Primo

    Primo Lonely Rider

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    So, i managed to find out my bike's flywheel puller measurement.It's a 33mm x 1.5 Right Hand Female.It came out with long and extended internet research and with help of my friends in the first place.There were not so many concrete answers to it actually:D

    Alan
    #30
  11. clintnz

    clintnz Trans-Global Chook Chaser

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    Had a go at fixing mine last week. My symptoms were a little different in that the starter had sounded like it was struggling a bit for a while, like it was low on volts, but the battery had plenty of juice & the connections to the starter looked good. Then it started just whizzing when the button was pushed & not turning over the motor at all. I got the NZ$9 SKF seal as above & took it apart.

    The 3-arm flywheel puller we had did not even look like shifting the flywheel, even with a few good whacks. The local KTM dealer didn't have the right flywheel puller :huh but there was one in the country so $49 & a day later I was the proud owner of the genuine factory service tool which did pop it off nicely.

    The spring did indeed look buggered, everything else looked OK so I put it back together with the new spring which seemed to fit well.

    Once the rest of the bike was back together I tried the starter & it worked, but it still sounded like it was struggling, & after about 6 starts went back to just whizzing & not working at all :cry

    I don't really mind that the cheap fix didn't work, it was worth a shot, but now I'm not sure if I need a whole new sprag clutch assembly, if the inner or outer hubs it engages on are worn, or if the starter motor or solenoid are worn out & the starter not spinning quickly enough is messing up the sprag clutch somehow???

    In the meantime my kick-starting technique will no doubt continue to improve :wink:

    Cheers
    Clint
    #31
  12. bikemoto

    bikemoto Tyre critic

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    I'm all ears on this one.

    The starter clutch on mine sometimes doesn't engage cleanly. Now a couple of times I've noticed it doesn't disengage cleanly. It takes a lot more effort to kick it when you are spinning the starter motor too!

    Normally for the first start of the day I kick it, both to ease the load on the starter motor and to keep my leg in practice. Sometimes I have to resort to the electric leg when I don't get it right and can't be bothered faffing with it any longer.
    #32
  13. DC950

    DC950 Microadventurer

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    have you been riding my bike? This problem is exactly what I have and your technique is mine!
    #33
  14. rapiti

    rapiti IOR Veteran

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    I bit the bullet on a new sprague clutch, and it works perfectly.

    Now that you have the tool, it will be a piece of cake should you choose that route.

    Good luck!

    #34
  15. TomW

    TomW Long timer

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    Great thread. Same problem here. Guess I'll start looking for parts and pullers. I need to read the kick starting thread. (Backfire nearly took my foot off the other day.)

    Cheers.
    #35
  16. clintnz

    clintnz Trans-Global Chook Chaser

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    Yep, mine did that a bit in the months preceding failure too. If I was you I'd drop in a new spring now.

    I've just been talking to the mechanic at the local shop, he said that the inner & outer surfaces that the sprag clutch engages on must be super smooth for them to work. The outer hub that bolts to the flywheel was pretty smooth in mine IIRC, but I think the inner hub on the gear may have been a little rough - the clutch pawls may have been dragging on it, hence the slow turnover when starting.

    Given that gear isn't real cheap & is probably 4 weeks away ex-Austria I might try pulling it out & giving it a polish up on the lathe, then reinstall with another $9 seal spring & see if that works. If it doesn't I'll bite the bullet & buy a new gear & sprag clutch.

    Cheers
    Clint
    #36
  17. losiu

    losiu wheelie addict

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    I've heard stories of broken legs or people flying over the bars (no idea if they're true but...)
    I have one tiny suggestion when kick-starting the beast:
    NEVER open the throttle. It'll rip your leg out of your butt.

    Give it a little bit of choke if it's cold and forget the throttle completely. When warm, do nothing but give it a decent kick. It'll never kick you back this way :)

    Opening the throttle is like giving it the permission to slap you :lol3

    L.
    #37
  18. bikemoto

    bikemoto Tyre critic

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    No-o-o-ooo? Why do you ask? Tyres looking a little more worn? Extra mileage on the clock? OK, I admit it, I've been sneaking over there when you are not looking and taking it for a hoon! :D
    #38
  19. bikemoto

    bikemoto Tyre critic

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    Hmm, know anywhere I can get a flywheel puller cheap?
    #39
  20. bikemoto

    bikemoto Tyre critic

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    Dunno that I'd agree with that. Seems to me that it will only kick back if you don't kick it all the way through, or you let it part-way up from the bottom before it fires up properly. If the kick start is all the way down, it is disengaged and won't kick back. Be timid with it and it will bitch-slap you. (I often start mine with a bit of throttle added.)

    Apart from reading the thread, the biggest suggestion I can offer is that it is speed at the bottom of the kick what you are after. Start slow, build up speed as you kick it through. Trying to begin the kick at a million miles an hour doesn't work so well. It leaves you prone to not having enough speed & momentum at the bottom of the stroke, as well as not being so well balanced and in control, both of which also expose you to not finishing the stroke with the lever fully down and disengaged - hence kick-back. I've only got 75kg to throw at the problem, technique is everything. I can jump up and down on the lever at compression and it won't move. Now with practice I can start it per the manual using the right leg while standing on the left side of the bike, or using the left leg while stradding the bike - except when someone is watching! :lol3
    #40
    clax likes this.