"new" 640 Adventure - stock exhaust?

Discussion in 'Thumpers' started by prossett, Mar 9, 2014.

  1. Kawidad

    Kawidad Long timer

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    Not a big LC4 expert here, but what you're talking about is long gone. It was developed by Sommers Racing in Germany. Many of the expert tuners did not like it and thought it was an overall negative, so it went the way of the dodo. I've read they developed it because the German DOT equivalent would not allow them to open up the top of the airbox, so they had to have a legal work around.
    #21
  2. prossett

    prossett Adventurer

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    Thanks for the explanation, Seikkalilu. That would explain the phantom middle hanger.
    #22
  3. gjcourt

    gjcourt n00b

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    Hey Kawidad,

    Thanks for the heads-up! I was fairly sure the air box cover was not made any longer. I don't mean to fill up this exhaust thread with air box related discussion but since it's started here I just as soon continue :D

    Does anyone know why the aftermarket air box cover was so despised? Was it strictly due to the ability of water to enter the air box/engine, or did the aftermarket cover affect performance negatively? Most stuff I read suggested that the aftrmrkt cover helped with air intake into the carb :dunno
    #23
  4. Seikkailu_R

    Seikkailu_R Been here awhile

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    I have currently both front and middle mountings occupied, and on rear i use y-shaped piece from -01 adventure.
    Very solid combination if compared to original one on front and one on rear mounting.
    625 SXC manifold also helps to keep things not moving around, as there is no joint for presilencer (no presilencer at all).
    #24
  5. tileman

    tileman Long timer

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    OK, heres a couple of queries for the brains trust here.

    I'm planning on building a low mount exhaust on my 03 640 adv. (I just am!!!!). Anyway I bought what I thought was a header pipe from a 640 similar to mine.

    BUT, the front 2 down pipes before the join are 31~32mm and after the join is 45mm. The original is ~35mm before and 50 after. The pipe I was planning on running to the muffler was ~45mm so the new pipe would suit. Th original fitted has a section as it passes through the frame that is about 45mm. (I don't have the pre-scilencer version).

    From what I can gather the torque will lower down in rev range which for my riding is not going to matter that much I don't think......as I said think, I may be quite wrong here.

    I may be able to send the pipes I got back to the seller (who knows ebay) and then fab a set up. Anyone have a thought on this one???

    I got hold of a exhaust calculator online and filled it in as best as I could. The area with the 45mm is about 20% less than the original 50mm, but from what I can gather that wouldn't effect the flow that much for where I would be reving the thing. Only thing is the calculator doesn't take into account the twin port head.......

    Thoughts?
    #25
  6. bmwktmbill

    bmwktmbill Traveler

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    Tile,
    Who cares if it works, it's about the sound!!

    Anyone who know anything about anything knows you want to string enough pipe to hook these up.

    http://www.bevelheaven.com/conti/pages/DSCN1636.htm

    Do you have any idea what you are looking at?

    As we said in the old days, "...time to lay some pipe!"

    bill
    #26
  7. Kawidad

    Kawidad Long timer

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    Yes, but supposedly it allow too much air into the air box and over leaned the mix, and then when you richened the carb, it was too much for the engine to handle.

    I personally believe part of the problem too is the LC4 (except for the newer versions) used too small of an air filter. It is the exact same filter used on their mini-bike models. This limited its ability to work properly in conjunction with the other parts of the intake and exhaust tracts. :deal
    #27
  8. tileman

    tileman Long timer

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    OK, just found out form the vendor that the pipe was from a 99 640 adv. Bit different in diameter from the 03 I have. Is the high flow head that mine has the reason for the enlarged diameter pipe or is it something to do with the use of the bike/ rev range torque etc……. any ideas anyone? He's happy to refund it so maybe I'll hang around until I find a correct one……or bite the bullet and fab one of my own…..
    #28
  9. motolab

    motolab Long timer

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    No I didn't.

    Regards,

    Derek
    #29
  10. docwyte

    docwyte Long timer

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    Maybe I misunderstood you then? What I understood from you is that you didn't even want to run one of these on your dyno with the KTM racing side air box cover on it if the bike still had a stock exhaust due to it running lean.

    That wrong?
    #30
  11. motolab

    motolab Long timer

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    The improved cylinder filling from the race lid causes detonation problems. A freer flowing exhaust improves the situation be getting the heat out of the engine better.

    Regards,

    Derek
    #31
  12. bmwktmbill

    bmwktmbill Traveler

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    http://www.advrider.com/forums/showthread.php?t=123569


    b
    #32