KTM LC4 (640) Thread Index

Discussion in 'Thumpers' started by meat popsicle, Jul 9, 2005.

  1. MNCherryinCA

    MNCherryinCA KTM Noob

    Joined:
    Mar 13, 2011
    Oddometer:
    577
    Location:
    Santa Clarita, CA
    Thanks Dirty. I took everything apart today. Pics posting soon.
  2. MNCherryinCA

    MNCherryinCA KTM Noob

    Joined:
    Mar 13, 2011
    Oddometer:
    577
    Location:
    Santa Clarita, CA
    Hi All,I started the 625 SXC Thursday at work and the starter motor sounded like it was slipping and not turning the motor over. This is a common symptom that is all over ADV about the LC4 PPs out there. I posted some stuff about "fixing mine" a few months back when I had a pretty severe problem with one of the starter gears breaking some teeth off and chewing up the inside of the flywheel. Got that one fixed by Lior's Motoride in LA. Lior used some parts I got from a friend which saved a big Death Valley trip for me. However, I think the sprague clutch we used was a bit loose. Here is a little step-by-step on how I took things apart today. When I get my new sprague from KTM, I'll take pics putting it back together and update the post.If everyone has seen enough of this problem, maybe we should take the best of all the different posts and link it to the LC4 links at the front of this index.

    Removed Seat
    [​IMG]

    Disconnected battery

    [​IMG]

    removed the plastic cover from the C/S area and the oil line from the top of the flywheel case.

    [​IMG]

    Removed the bolts on the stator cover and pulled it off. I inspected the stator. Everything looked pretty good. No big chunks of metal anywhere. There were some small shavings on the magnetic area. You could barely see them on the rag.

    [​IMG]

    The stator still looked very good. Thank God!
    [​IMG]



    [​IMG]

    Here are some of the small bits stuck to the magnetic parts:
    [​IMG]

    The flywheel itself looked good in the front and inside. Now to take it out.

    Got the impact wrench out to remove the reverse-threaded nut from the flywheel
    [​IMG]

    Used a 24mm socket. here is the nut and thick flat washer:
    [​IMG]

    Got the special flywheel removal tool ready...

    [​IMG]

    Used the impact wrench again and removed the flywheel. i just put the bike in 5th gear. Didn't need to even use the brake or anything. I was surprised the impact wrench worked so well!

    Here is the flywheel.

    [​IMG]

    Inspecting the back of the flywheel and the sprague clutch, everything was in place.

    [​IMG]

    I inspected the surface of the gear hub that rides against the ID of the sprague clutch and it looked pretty good.
    After using snapring pliers to remove the black snapring, I removed the sprague clutch.
    Here is the sprague clutch removed from the back of the flywheel. All the bits and pieces were there, albeit a bit loose. however, i do not know how loose it SHOULD BE until I get the new one from KTM. Inspected the rotor hub that rides against the OD of the sprague and it looked good.

    [​IMG]

    [​IMG]

    Now I took the outer shell off the motor to inspect the starter gears for broken teeth. good news! No broken teeth!!!

    [​IMG]

    This is the one that was broken into pieces on me last time. Seems fine now.

    [​IMG]

    Now for the really fun part! Putting it back together...I need to get the new sprague clutch and gaskets in. In the mean time, with all of these parts removed...time for some good cleaning!

    A couple of things noted...

    The impact wrench made this REALLY EASY. I highly suggest using one if you can swing it.
    Removing the shell to get at the gears was just a little tricky. the bolts all came out pretty easy, but it just didn't want to come off where the starter motor comes into it on the upper left. I used a big long screwdriver and a hammer to lightly tap it from the left side of the bike. maybe that's what that little tab is there for?


    I will report more about the new sprague clutch vs old when i post up the re-assembly.

    OK...it's a few days later and I got the new sprag clutch in, so here is the reassembly.

    First of all, I had to start out with some good hops

    [​IMG]

    First I put a new "form ring" into the groove in the little cover that covers up the starter gears and installed the cover with one of the capscrews that doesn't go all the way through.


    [​IMG]

    Now I used a new gasket to seal the flywheel cover.

    [​IMG]

    I used Loctite 515 to dress the gasket on both sides before installing the gasket and the cover.

    I had to jimmy the cover a little and use the threading of the screws to move the cover into its final position. Here it is installed.


    [​IMG]

    [​IMG]

    Before putting the flywheel back in, I noticed the threads on the end of the shaft were pretty dirty. I cleaned them gently with a wire brush and then wiped the dust out.

    [​IMG]

    Now to replace the old sprag with the new one.
    [​IMG]

    Old sprag on bottom, new one on top.

    [​IMG]

    Like I said before, the new one had a much tighter spring.

    here is the new one installed into the hub on the back of the flywheel
    [​IMG]

    I had to use a few taps with a rubber mallet to get the flywheel to get back onto the tapered shaft. It was actually pretty easy.

    [​IMG]

    Now to thread the thick flat washer and reverse threaded nut back on...
    [​IMG]

    I used the impact wrench to torque the nut down. I may be screwing up here in not using a torque wrench, but i have to believe the impact wrench is putting more torque on this nut than I possibly could with a wrench or even a breaker bar.

    [​IMG]

    Now to use a new gasket on the stator cover, I also used Loctite 515 to dress this gasket on both sides...
    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    I did smear the 515 on both sides of the gasket.
    [​IMG]

    Cover installed!
    [​IMG]

    Now to install the oil line

    [​IMG]

    Hooked up the battery and said a prayer...

    Turned the key, pulled the choke...hit the button....vroom!! Success!!! YES!!!!

    This bike had not fired this quick the entire year+ I have owned it! The starter motor is DEFINITELY still good. The thing cranks the engine over with ease now! YYYYYEEEEESSSS!!!

    OK...so I only waited about 30 minutes after putting it back together, so when the engine heated up, I started to get some smoke. I think i had a little excess loctite goop that was not cured that was squeezed out of the gakset. I THINK that's what is smoking, but not sure...I looked for any hoses, wires, etc that might be resting against the engine and didn't see anything. I'll try again tomorrow after the loctite is fully cured/dried out.

    I also noticed the 515 loctite said it was for 300F applications. Maybe it was the wrong stuff to use, but oh well...we'll see.

    Good news is that the sprag clutch is fixed!!! Yahoo!
  3. mcguyver

    mcguyver Long timer

    Joined:
    Dec 24, 2005
    Oddometer:
    1,297
    Location:
    BRISBANE AUSTRALIA
    Thanks for posting. I too had the starter intermediate gear loose a tooth recently. Seems to be becoming more of an issue as these bikes get some miles on them.

    These posts with pics are fantastic for non me hanical types like me to follow step by step.
  4. LouisWu

    LouisWu Adventurer

    Joined:
    Feb 3, 2011
    Oddometer:
    12
    A while ago some professional revised my engine, because of failing of the mean bearing. They replaced it with the 660 roller bearing, along with all other bearings. In the mean time i have driven about 5000 km and i performed an oil change. This is what i found:
    [​IMG]


    To make sure i changed my oil again after 600km or so. Then i found this:
    [​IMG]
    [​IMG]


    To me it looks like some roller bearing is shot. Any idea's where to start looking?? I was thinking about pulling the left and right cover of the engine. Or maybe even the rocker cover. But that is as far as i want to go. I want to take her offroading through the pryrenees (east to west), but she needs to make it off course.

    Symptoms:
    - The accu is quickly drained (but still charging with 13V when revving). Because of that (I think) she does not start electrically when cold, but after riding for a while she starts good;
    - I did find some oil inside (4 spoons) the airfilter, and very little oil was leaking from behind the chainwheel. But this could be because of overfilling when doing the oil change mentioned above.

    Anybody got some hints where to look, and for what????

    Your advise would be greatly appreciated;-)
  5. MNCherryinCA

    MNCherryinCA KTM Noob

    Joined:
    Mar 13, 2011
    Oddometer:
    577
    Location:
    Santa Clarita, CA
    So I have a ride planned for this weekend, leaving Friday. I have a new sprague clutch on order, but it may not get here on time.
    My current part is in one piece. The spring is a little worn, but it is in one piece. the little pieces can move in and out pretty easy (into and out of their regular diameter of the assembly).
    When I am holding the flywheel in my left hand and the sprague is installed in the hub on the back of the flywheel, I can easily spin the sprague clutch around in the ID of the hub. Should that be reall easy to turn in there are should it be gripping better? Part of me wants to say that if I get the new part, it would actually be spung together tighter from the outside, making it more likely to be even smaller on the OD and therefore rrotate even more freely inside the hub than an older worn-out one.
    Blah...blah..blahh..here's the real question...
    if all the other parts look good and the sprague is how i describe, should I put it back together and cross my fingers or am I asking for trouble?
  6. MNCherryinCA

    MNCherryinCA KTM Noob

    Joined:
    Mar 13, 2011
    Oddometer:
    577
    Location:
    Santa Clarita, CA
    Based on my recent experience, I would check the right side stator cover. i rolled up a lot of metal in there from a broken starter gear and some ended up on a plug like yours.

    However, even before that, I always get some shavings on the plug. Maybe these things always just do that?
  7. Tonicu

    Tonicu Been here awhile

    Joined:
    Dec 9, 2011
    Oddometer:
    169
    Location:
    Spain
    I posted a couple of weeks ago cold start problems after fitting an SXC can and dismantling the bst.
    It needs about 20 seconds hitting the start button to fire up when cold. Trouble is it now takes about 10 seconds when hot, whilst before the engine started as soon as I hit the button.
    Apart from these starting problems I haven't noticed any changes in performance, fuel consumption and the spark plug looks ok with the typical brownish colour.
    I think I mentioned the engine did not start - it didn't even turn - if I pulled, even a tiny bit, the choke lever.
    The carb was dismantled a couple of months ago and I've done about 3k kms since then. Both the jet and float needles looked fine without any visible wear, so I didn't change them.
    It's a 640 E '03 with 45K kms.

    I'd say the trouble is in the carb, but where? Any ideas?

    Also I noticed today a couple of leaks. The timing sight glass - quite expensive at almost 30€ - and now the handlebar clutch fluid reservoir. Apparently there's no gasket there.
  8. MNCherryinCA

    MNCherryinCA KTM Noob

    Joined:
    Mar 13, 2011
    Oddometer:
    577
    Location:
    Santa Clarita, CA
    Tonicu, are you holding the starter button down for 20 consecutive seconds? I think that is not going to be good on your starter, starter gears, etc. My mechanic and several other sites I have visited say not to hold the button down for more than a couple of seconds and then let it rest for a few before trying again.
  9. Tseta

    Tseta Lost

    Joined:
    Nov 30, 2008
    Oddometer:
    674
    Location:
    On the road
    I replaced the leaking timing sight glass with a simple bore plug (like this), much cheaper at just a few euros from my local industrial supplier. I haven't really had any need to look through the sight glass so far, so the regular plug works just as well.

    Cheers,

    Tseta
  10. MNCherryinCA

    MNCherryinCA KTM Noob

    Joined:
    Mar 13, 2011
    Oddometer:
    577
    Location:
    Santa Clarita, CA
    OK...I'm quoting myself here, but my question is now moot! Chip got my new sprague clutch to me super fast. Got it already and will try to install it tomorrow. The new sprague clutch is MUCH firmer/tighter than the old one. The spring is much tighter. i hope this fixes the problem. I will post pics from my reassembly and report the results.
  11. Alik

    Alik viertaKTMotor *****

    Joined:
    Nov 7, 2010
    Oddometer:
    270
    Location:
    Poznan, Poland
    Forget the expensive timing glass - never used it for real. I followed these advice: http://www.adventure-enduro.de/motorrad/ktm/motor/schauglas/ and forgot about leaky window since.
    Or you could try to reseal it with an apropriate sealing silicone (must be of "sensor safe” type).

    Hydraulic clutch reservoir - You mean these rubber inside the reservoir is missing? Or a leak from the inside of the clutch master cylinder at the handlebar? There is a piston rebuild kit available from the KTM for about 30 EUR. Part # 50302032000.

    I would start with a thorough inspection of the carb innerings - starting with inspection of the enricher circle, float height, float seat o-ring, float needle, float needle seat. Start looking for answers in these thread: http://www.advrider.com/forums/showthread.php?t=347184
  12. bmwktmbill

    bmwktmbill Traveler

    Joined:
    Jul 16, 2005
    Oddometer:
    5,285
    Location:
    Traveler
    Tonicu,
    Which carb is on your machine?
    bill
  13. Tonicu

    Tonicu Been here awhile

    Joined:
    Dec 9, 2011
    Oddometer:
    169
    Location:
    Spain
    Hi, Bill. It's the stock BST40 modified as per Laramie's bible, main jet 160, pilot jet the standard 45.
    Alik, Cherry and Tseta - glad to hear from you -, thanks for the advice.
  14. LouisWu

    LouisWu Adventurer

    Joined:
    Feb 3, 2011
    Oddometer:
    12
    I was thinking the same. I am ordering gaskets and will pull the right side shortly. Let's hope this will be the cause.....

    Maybe someone else has other ideas????
  15. MNCherryinCA

    MNCherryinCA KTM Noob

    Joined:
    Mar 13, 2011
    Oddometer:
    577
    Location:
    Santa Clarita, CA
    Hey All,
    If anyone is interested, I updated my postings from earlier this week to show pics of the reassembly with a new sprag clutch. Nothing mind-blowing here, but it works now!:clap:clap:clap:clap:clap:clap:clap
  16. bmwktmbill

    bmwktmbill Traveler

    Joined:
    Jul 16, 2005
    Oddometer:
    5,285
    Location:
    Traveler
    Ton,
    Just a guess...get some slack in the choke cable, pull the choke full on and roll the cold engine over a couple of times, close the choke and start the machine without using the throttle to help, once running blip the throttle to warm it up.

    To set the fuel screw advance the idle to 1800 rpm, turn the screw in and out for fastest idle position, readjust the idle to 1450 rpm...

    Is the fuel screen clear in the fuel inlet tube?
    Post your problem on the BST40 thread, get Motolab's advice.
    bill
  17. gunnerbuck

    gunnerbuck Island Hopper

    Joined:
    Nov 19, 2005
    Oddometer:
    4,431
    Location:
    N.V.I, B.C.
    There has been a few suggestions put forward for you to check your starter sprauge clutch, have you looked at it yet? Perhaps some of your starting issues can be chalked up to this part failing... If it is slipping it will not turn the engine over fast enough to produce a proper firing sequence... Once disassembled you may be able to apply losius starter clutch fix :http://advrider.com/forums/showthread.php?t=222515
  18. Tonicu

    Tonicu Been here awhile

    Joined:
    Dec 9, 2011
    Oddometer:
    169
    Location:
    Spain
    Thanks for telling me off, Gunner. :smooch
    I didn't take a look at the sprague clutch for two reasons :
    First one is it doesn't make ( to me ) any weird sound as it seems this thing produces when it goes wrong.
    The second one is I don't have a flywheel puller and I don't know anyone in the nearby I could borrow it from.
    They say a picture is worth ( over ) a thousand words, so here goes a video in which it takes a long time, more than 30 seconds to get the engine started. Yep, I know it's not good for the starter motor and the battery, but I wanted to show how long it took.
    http://youtu.be/xnZJyf5_1zA

    Bill, thanks for the tips, I'll have a look and see what I find.
  19. juames

    juames Have Fun, Don't Die!

    Joined:
    Aug 16, 2008
    Oddometer:
    2,555
    Location:
    Ottawa
    Well if you starter wasn't fried before that video, it probably is now! :eek1 That sounds to me like a fuel issue. There's no way that the bike wouldn't be flooded after turning over that long, unless its wasn't getting fuel.
  20. MNCherryinCA

    MNCherryinCA KTM Noob

    Joined:
    Mar 13, 2011
    Oddometer:
    577
    Location:
    Santa Clarita, CA
    Agree. HAS to be a fuel/carb problem. Starter sounds pretty healthy.