KTM LC4 (640) Thread Index

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

  1. ham2007

    ham2007 Adventurer

    Joined:
    Jul 22, 2013
    Oddometer:
    86
    Thank you for the explanation. This is all very relevant to my current carb situation on my 640a. That hopefully I will get a chance to take a look at this weekend and well if I can’t figure it out you guys will be hearing from me ha
  2. Whodatschrome

    Whodatschrome Long timer

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    May 4, 2015
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    4,684
    Location:
    North of North Plains
    It’s off to the races!

    I decided at the last moment to race my 640A at the Virginia City Gand Prix this year. I threw it on my front hitch of my motovan. No problems during the 600 mile trip. The race starts tomorrow morning (Saturday). There’s a second race on Sunday, and that’s why the 990A is on the rear hitch!


    Driver side view
    BFC2E1CF-B6C1-4A78-A011-5CEF8473F925.jpeg BED39DDA-4220-414B-99D7-D91DF7D53B44.jpeg
    CA Stu, bikemoto, burntaler and 6 others like this.
  3. PaulBarton

    PaulBarton Long timer Supporter

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    Apr 14, 2015
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    Seattle
    Go get 'em, Tiger! look at all that orange!!
    Whodatschrome likes this.
  4. motolab

    motolab Long timer

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    Feb 16, 2006
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    What brand is the front arrangement? Is the rear the same?

    Regards,

    Derek
  5. motolab

    motolab Long timer

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    Sir, you're welcome!

    Regards,

    Derek
  6. Whodatschrome

    Whodatschrome Long timer

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    Rear is a Versahaul. The front was made by a local guy who was selling MANY of them. I have no idea his brand was called. He doesn’t make them anymore. The main tray is aluminum extrusion that he had made from his own die design. Everything else is heavy wall steel tube. It doesn’t flex at all and is very stout. It’s much lighter weight to pick up than my Versahaul. I think it’s rated for 600lbs(?), but I think my Versahaul is stronger. I haven’t tried carrying my 950 on the front of a vehicle, but then again, it’s probably not a good idea to have that much weight up front even if a frame mounted receiver has that high of a rating .
  7. skibum69

    skibum69 slave to gravity Super Supporter

    Joined:
    May 14, 2006
    Oddometer:
    15,806
    Location:
    New Melbourne, Newfoundland
    Giv 'er!
  8. Whodatschrome

    Whodatschrome Long timer

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    May 4, 2015
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    4,684
    Location:
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    The 640 was a crowd favorite today at the race! I did finish. No idea what place. The course was a SUPER rocky butt kicker! My suspension was nice, but I should have spent the time to mess with the clickers to soften up the compression for this particular course. I started the race on a full 6.6 gallons, so at the race went on my 640 handled better with each lap. A 300 xc-w or a 450xc-w would definitely be the bikes to go with out here in this terrain...as well a 640 some (ok, one person) might think.

    The weather was pretty good today. It was pretty cool. Maybe in the low 50’s, so it would be difficult to overheat your body. I went through close to 2.5 liters of water in my hydration bladder. I would have drank more,
    but I was trying to conserve it. Being that it was a multi lap race, I was hoping to not use the pits at all. But at about 3 hours into the dusty race, my air filter was clogged with dust, so my 640 ran like an underpowered turd. It made it hard to climb hills in 2nd gear (with 15:44 sprockets). I limped into the pit area and removed the airbox cover and pulled the “filter skin” off the air filter. That dang airbox cover takes FOR EVER to screw back on!

    anyhow, with a clean filter the bike was back to normal power levels. I did two more laps around the course. I think I was out racing for about 4.5 hours? I’ll have to wait for the results to be posted to know for sure. I did focus on not griping the handlebars too tight. I came away with zero blisters or even any hot spots on my hands. My body is definitely sore from the race.
    Hopefully it will recover enough in 12 hours for the second race tomorrow...when I’ll be racing my heavy 990. Ugh!

    this is the only pic I have from after the race.
    Hopefully more will turn up on the inter web?
    E9FDD6FE-17FF-40B8-AE8E-C56E93778350.jpeg
  9. John Macdonald

    John Macdonald Long timer

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    Oct 2, 2002
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    1,951
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    Nevada
    Excellent!
    Whodatschrome likes this.
  10. motolab

    motolab Long timer

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    Feb 16, 2006
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    Thank you, sir!

    Regards,

    Derek
    Whodatschrome likes this.
  11. skibum69

    skibum69 slave to gravity Super Supporter

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    New Melbourne, Newfoundland
    Excellent work!
    Whodatschrome likes this.
  12. Wanderer7

    Wanderer7 long time rider

    Joined:
    Apr 11, 2013
    Oddometer:
    118
    Location:
    Montrose, CO
    Change of plans.
    I want to install 32mm exhaust valves and port the exhaust. Can someone recommend what brand of valves and possibly where from? Do the existing seats have enough metal, or do I need to buy larger seats as well?

    2nd, does the stock exhaust header have good enough flow, or do I need a larger diameter header pipe as well?


  13. motolab

    motolab Long timer

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    Improvements can certainly be made this way, but keep in mind that the high flow head's ports are not only larger, but also raised, and that the room to do this was created by raising the valve spring seats. To create room for larger ports, the valves are also on wider centers on a high-flow head model.
    The OEM high-flow exhaust valves should still be available.
    From what I remember, the seats are fairly thick-walled, but it would be best for you to measure yourself.
    The main issue with the pre-high flow exhaust system is the lack of flow through the pre-muffler (as the muffler itself can easily be replaced with an Akrapovič or Leo Vince slip-on without quiet insert). Of course the full Akrapovič system would be the ultimate, but a significant improvement can be made by installing a non pre-muffler equipped s-bend or a high flow header (which has the s-bend built in).

    Regards,

    Derek
    Wanderer7 likes this.
  14. Wanderer7

    Wanderer7 long time rider

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    Apr 11, 2013
    Oddometer:
    118
    Location:
    Montrose, CO
    Thank you Derek, I greatly appreciate your help!
  15. Desert Silver

    Desert Silver Desert Rat

    Joined:
    Jul 27, 2007
    Oddometer:
    121
    Location:
    Ash Fork AZ
    I have a 03 625 that I'm selling and the shift shaft seal is leaking. Can that seal be replaced with out pulling the side cover and if so how.
  16. RockyRue

    RockyRue Long timer

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    Dec 19, 2008
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    2,892
    Here is a picture
    I could probably pull that out with a couple of long screws
    [​IMG]
  17. RockyRue

    RockyRue Long timer

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    Dec 19, 2008
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    2,892
    Is this you?

    Virginia City Grand Prix - ADULTS SAT/SUN Virginia City, NV 10/23/2021 KTM 399
    854 OASat - 202nd, OASat - 202nd
    D Sport Am/Exp - 2nd
    Adventure - 1st

    If it is, good job, 1st in ADV

    https://www.moto-tally.com/vcgp/results.aspx
    Whodatschrome likes this.
  18. Whodatschrome

    Whodatschrome Long timer

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    Ha, ha! Great detective work. Yes that is me! I got beat out by an XR650R in the “dual sport” class. The course was SUPER rocky, which I’m comfortable with riding in, but I never got around to adjusting the clickers on the suspension to accommodate for that particular terrain. My 640’s suspension is currently dialed in for higher speed desert riding, so the race was a very bumpy ride for me! It was my fault for not dialing in the clickers. I wasn’t even planning on racing my 640 in Saturday’s race. But about 4 hours before I left for the race, I thought “why the heck not?”...let’s see how much punishment my body can handle. So I rushed for 4 hours prepping the 640. Most of the prep was just stripping any extra weight off the bike. I’m currently midway through my version 3.0 LED headlight build, so only one light is installed.

    Racing two days in a row is a butt kicker for sure. Saturday’s race on the 640 was SUPER dusty. Sunday’s race on my 990 was SUPER DUPER MEGA cold, rainy, and muddy! Apparently it was the worst storm in years at VC? I don’t know if that was true or not, but the conditions were downright miserable.
    bikemoto and PaulBarton like this.
  19. PaulBarton

    PaulBarton Long timer Supporter

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    Nice work!! f*ing XR's!!
    Whodatschrome likes this.
  20. Dolly Sod

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

    Joined:
    Aug 18, 2003
    Oddometer:
    18,901
    Location:
    Richmond, Va

    I just replaced this seal on my bike. It came out with one small jewelers screw driver. It popped out surprisingly easy.
    Desert Silver likes this.