640 Pre 03 to 03+ cylinder swap

Discussion in 'Thumpers' started by gunnerbuck, Nov 10, 2012.

  1. gunnerbuck

    gunnerbuck Island Hopper

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    I picked up an older cylinder for my 03 spare engine build and had to do a small mod to make it work, so I figured I would share it:
    [​IMG]
    The pre 03 is on the left and takes a much larger dowel
    [​IMG]

    [​IMG]
    Made up a bunch of slugs to convert the hole size
    [​IMG]

    [​IMG]
    The dowel slug in place:It can be used to fit the 03 + cylinder to the older cases or the older cylinder to the 03 + cases

    The pre Hi- flo engines take a thicker base gasket so I need to establish if the 01 cylinder is a fuzz shorter or if the 03 just ran a slightly higher compression ratio... I will go with the thicker pre- 03 gasket regardless when I assemble the spare engine...
    #1
  2. bmwktmbill

    bmwktmbill Traveler

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    Thanks Gunner,
    That was a black hole.
    bill
    #2
  3. gunnerbuck

    gunnerbuck Island Hopper

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    Yep , it's good to have a machinist friend to help out on the odd project...
    #3
  4. warewolf

    warewolf Tyre critic

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    Neat job. I like elegant solutions. :1drink
    #4
  5. bmwktmbill

    bmwktmbill Traveler

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    Gunner,
    Now you have me thinking and wondering, is it settled that a Hi-flow head/cam will fit on a low flow cylinder and vice versa.

    I have forgotten if that is settled.

    Your ideas?
    bill
    #5
  6. Alik

    Alik viertaKTMotor *****

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    Well guys there is a factory solution to that (as I believe):

    part # 579.30.023.000 ZENTRIERSTIFT GESTUFT 4/9,8 CENTERING PIN GRADED 4/9,8

    no need to grind and co. :)
    One need 2 of them to make it work.
    #6
  7. gunnerbuck

    gunnerbuck Island Hopper

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    Hi Bill,

    Yes, a high flo head will mount on a lo-flo cylinder, that is the combo I will be using on my spare engine build...

    I have quite a mix of parts from both pre and post 03 going into this engine...
    #7
  8. gunnerbuck

    gunnerbuck Island Hopper

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    Yep, looks like the exact part needed to do the swap... When the later model LC 4 -400 went to a juice clutch they used the Hi Flo engine cases... Instead of changing the 400 cylinder because of the different sized dowels KTM did the exact thing I did to make it work... The downside is that those parts will likely get backordered to the factory...
    #8
  9. Alik

    Alik viertaKTMotor *****

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    Here in Eastern Europe we can get almost every part from the KTM factory in just 5 days - sometime even less, maybe 3 :)
    #9
  10. gunnerbuck

    gunnerbuck Island Hopper

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    Most of the 640 parts I order are usually in the dealer in 3 days from the warehouse in Ohio, if it has to come from the factory then it's 2 weeks...

    I ran a part # 579.30.023.000 search through some North American KTM dealers and no results came up... Even special order part #s usually still yield results when run through a search, I wonder if that part is even still available?
    #10