KTM LC4 (640) Thread Index

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

  1. bmwktmbill

    bmwktmbill Traveler

    Joined:
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    5,610
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    Dawggg,

    Take a good look at your oil.
    You wll get bubbles in the coolant if the waterpump seals are shot and the valve guide seals and guides are also shot.

    Is your airbox dry or is it full of oil?
    Is the engine oil turning milky?

    Is there oil in the coolant?
    bill
  2. beek-02

    beek-02 blazing a trail

    Joined:
    Sep 10, 2009
    Oddometer:
    113
    Location:
    California City, Ca
    Hi Bill,

    I've worked on quite a few bikes , cars, etc. Have a pretty fair working knowledge of how motors work but cannot figure out how bad valve guides/seals could continue to a bubbling radiator? Not questioning your knowledge just looking for some enlightenment.

    Beek

    Sent from my SCH-I535 using Tapatalk 2
  3. faustinoeldelbarrio

    faustinoeldelbarrio Faustino

    Joined:
    May 20, 2011
    Oddometer:
    33
    Today I took off the carb from my 06 lc4A and saw something I had never noticed. Apparently there is s division in the middle of the intake to send separate currents od mixture to each admision valve. What bothers me is that the work doesn't seem as an original feature, it much more looks like a DIY version. Here is a picture of what you see when you look in the direction of the valves (valves appear as bright figures with a copper like color):
    [​IMG]

    I also took down the left light, and noticed there is a spot where a bolt might go, but i am not sure if there should actually be something there. The left light actually has a threaded hole that matches the spot I signaled in red in the next picture:
    [​IMG],

    Anyone has any opinions on these issues?
  4. Dolly Sod

    Dolly Sod I want to do right, but not right now

    Joined:
    Aug 18, 2003
    Oddometer:
    15,254
    Location:
    Richmond, Va
    Split intake runner is normal.

    [​IMG]

    ... Maybe someone did some shad tree porting/polishing, though I've read that the porting and polishing from the factory looks poorly done.
  5. 640 Armageddon

    640 Armageddon Do or Do Not. There is no try.

    Joined:
    Mar 4, 2009
    Oddometer:
    3,565
    Location:
    Greece
    My 2002 was exactly the same, the bolt was missing. I bought a second set of headlights on ebay and there is a vibration dampener there. This is the same dampener as the one used in the light support bracket.
    I used to run the lights without this dampener and nothing weird happened, I have LED's now so :huh

    D.
  6. faustinoeldelbarrio

    faustinoeldelbarrio Faustino

    Joined:
    May 20, 2011
    Oddometer:
    33
    Thanks to both of you, I'll consider buying the dampener to give extra support for the lights.
  7. bikemoto

    bikemoto Tyre critic

    Joined:
    Oct 24, 2004
    Oddometer:
    2,842
    Location:
    Nelson, New Zealand
    "Looks" being the important word. There is no correlation between looks and flow. Some of the roughest porting generates great flow characteristics. Only the flow bench (or dyno) can tell you what is "beautiful". :cool:
  8. gunnerbuck

    gunnerbuck Island Hopper

    Joined:
    Nov 19, 2005
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    5,140
    Location:
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    [​IMG]

    This hole is unused on the left side of the framework, on the right side it supports the horn and wiring support...

    I use these on both sides to bolt my LED light support brackets on, it keeps them tucked in nice and tight out of harms way as pictured below...
    [​IMG]
  9. bmwktmbill

    bmwktmbill Traveler

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    Beek,
    Please, you should question my knowledge!!
    Like you I have worked on a little bit of everything including people as I am a nurse.

    As for the LC4, I think possibly failing valve guides and seals allows engine compression into the top of the engine forcing engine oil into the air box. If the water pump seals are also bad engine oil and air could be forced into the coolant as well.

    I know that sounds crazy but I had a situation like that happen to me(I think).
    I had bubbles and oil in the coolant/radiator, coolant in the oil and oil in the air box.

    I thought I had a cracked head so I tested it using Gunner's method...it was not cracked. So why did I have so much oil in the air box and oil in the coolant, air bubbles in the coolant and coolant in the oil?

    I rebuilt the water pump and rebuilt the head with valves, guides and seals.

    All is well now.

    When I removed the head the head gasket was perfect. I did replace it.

    bill
  10. Low594

    Low594 Adventuring Creep

    Joined:
    Oct 28, 2008
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    1,217
    Location:
    Oakland, CA
    My headlight has that dampner, but it secures to a bracket just inside of where you outlined, not visible in this pic.
  11. hAjPR

    hAjPR Adventurer

    Joined:
    Nov 30, 2012
    Oddometer:
    31
    Location:
    Czech Republic (that's in between Germany&Poland!)
    I read somewhere that the KTM speedo can be modified that the digits of Trip 2 become the same size as speed digits? Can anyone advise, please? It's 640A '07 plus I got the tripmaster switch. Thanks!
  12. Kawidad

    Kawidad Long timer

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    Jul 9, 2005
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    5,683
    Location:
    Central Coast, Cal
    I'm in too. I just bought a 2001 640 Enduro from a buddy, so I guess I've got a lot of reading to do. :D
  13. Dolly Sod

    Dolly Sod I want to do right, but not right now

    Joined:
    Aug 18, 2003
    Oddometer:
    15,254
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    Following up on this, Gerst sent me a link to some photos of the bracket he has. I'm nearly 100% certain that it is not the SW-Motech bracket, but I'm not sure if it's something else that will work on and ADV. I haven't seen it before, but I've only been at this a short while.

    [​IMG]


    [​IMG]

    [​IMG]

    [​IMG]

    Anyone seen this before, and know if it will work on a 640ADV? It vaguely looks like the KTM bolt on option, but it looks like the spring would have to be routed under the stand instead of on top?

    I'm about ready to have a friend weld a tab on my frame so I can run a center stand and side stand, but if this would work as a bolt on option, I'd prefer that.

    Thanks..
  14. rxcrider

    rxcrider Long timer

    Joined:
    Apr 19, 2007
    Oddometer:
    1,457
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    N Ridgeville OH
    That looks exactly like the bracket for the SW Motech side stand I had on my '97 400RXC. It would not work with a center stand and I'm not sure if it would fit a newer 640, even if you removed the center stand.

    Here it is at twisted throttle:
    http://www.twistedthrottle.com/sw-motech-sidestand-ktm-lc4-with-21-18-enduro-rim-size
    [​IMG]

    It is an automatic up stand so watch your shins when you lift the bike off the stand. Also keep the pivot point clean and lubed. With the spring mounted on the inside, any play that develops allows the stand to be pulled in and eventually the foot starts rubbing a groove in the swing arm. It also doesn't tuck in very well or pul up very high so it is prone to getting dragged through the mud if you are in a deep rut.
  15. bmwktmbill

    bmwktmbill Traveler

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    Jul 16, 2005
    Oddometer:
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    Guys,
    I have lowered my 640a so the center stand an kick stand have been either shortened or bent to function properly and to hold the machine at the proper angle.

    The tubing is good quality and if heated, bent and cooled slowly the strength is not affected. You can also braze on the tubing if you want to add different feet or other accessories.

    Rustolium grey paint is a good match to KTM frame grey.
    bill
  16. Low594

    Low594 Adventuring Creep

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    I just changed the 1piece Throttle Assembly/Right Control Pod out for the Pod from a 950(not PlugNPlay) and the independent Throttle from a 250XCF. I did this so I can adjust the cable angle without affecting where the starter button sits. The following I posted in my build thread!

    BTW, I've got lots of changes going on, in prep for a trip to Death Valley in a month and a half! :evil
  17. Dolly Sod

    Dolly Sod I want to do right, but not right now

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    You nailed it, thanks. :thumb
  18. Mo-Tarded

    Mo-Tarded Been here awhile

    Joined:
    Jun 25, 2008
    Oddometer:
    191
    Location:
    Show Low, AZ, USA
    So I got the BST parts marked with a '#' kit. Pulled the carb off, found nothing remarkable... R/R'd all the elements in the kit, put it all back together, temporarily hooked up the tank, turned on the gas and it's leaking worse.

    So I pulled the float bowl off while the carb is on the bike and of course the float bowl frame and floats essentiall off/out.

    I put the float frame back up into the fuel intake seat and turned the gas on and toggled the floats up and down. It was still leaking gas in the "Up" position. The only other leak path would be around the rubber "O"-ring around the float bowl frame insert into the gas intake itself.

    Went to the local H/W store that has a bunch of rubber "O" rings and found one to fit. R/R'd the one on the frame and repeated the above. No leak...

    While I found the solution, the problem is the "O" ring that failed (dried/shrunk/fatigued) is NOT in the "#" kit. It comes with the float bowl/frame assy.

    It's all back together and runs flawlessly through the entire power band.
  19. Low594

    Low594 Adventuring Creep

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    Great timing! Mine just started doing the same!
  20. Kawidad

    Kawidad Long timer

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    Central Coast, Cal
    Just make sure you are buying fuel safe o-rings or you'll be back in there soon with an even worse leak. Just say'n. :D