KTMonda CR500 450sxf conversion

Discussion in '2 smokers' started by jar944, Jan 20, 2012.

  1. Research Rat

    Research Rat thrasher

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    What made you decide on a 91 vs. other years?

    Re the clutch, is it a hydraulic unit?

    Thanks,
    Scott


    #41
  2. jar944

    jar944 Been here awhile

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    91-2001 are basically the same with some very minor differences (color & trans ratios) & Yes the magura is hydraulic.
    #42
  3. Research Rat

    Research Rat thrasher

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    I'm keeping my eyes peeled for crs.

    With the magura, is it as simple as plug and play or is there more involved with the install? Have you thought about adding a rekluse (if there is even one available for the cr motor.)


    #43
  4. jar944

    jar944 Been here awhile

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    yes it'a a simple bolt on. as for the rekluse i'm personally not a fan.
    #44
  5. Research Rat

    Research Rat thrasher

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    Jared,
    Do you know if the 2008 450 EXC frame would work as well for the conversion as the 450 sxf/xcf? From the fiche I can tell they are different part numbers.

    Thanks!
    -Scott
    #45
  6. jar944

    jar944 Been here awhile

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    It should, they are wider (front to rear) in the cradle.
    #46
  7. jar944

    jar944 Been here awhile

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    #47
  8. PSchrauber

    PSchrauber Been here awhile

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    #48
  9. jar944

    jar944 Been here awhile

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    #49
  10. PSchrauber

    PSchrauber Been here awhile

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    The clamp is certainly a problem in the optical design. My intension are about the use or maintance, the way the deco is used now is pulling and open the deco, then starting the engine wjile pulling the öever to close the valve again.

    The setup I mentioned and is used for Rotax engines for example is one action, a spring holds permanently the valve closed, by pulling the lever you open the the valve, when you loose grip to the lever the valve will automatical close again. Isn't this much more comfertable and easier to use?
    #50
  11. jar944

    jar944 Been here awhile

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    AHH! I understand what you were referring to. You are misunderstanding how the valve works. It closes by itself once the engine fires (or you release the lever while kicking) From the compression/combustion pressure. Pulling the lever opens the valve.

    I only manually closed it in the video to show it's operation.:beer
    #51
  12. PSchrauber

    PSchrauber Been here awhile

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    I hope this mechanism works (closes) well without any spring. When the spring is loosing tension it will get spitty around the deco in my experience, (This happend after a decade or so). They also have the tendency too loosen. I therefore check them once or twice a year if they still sit thight.

    [​IMG]
    #52
  13. jar944

    jar944 Been here awhile

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    It closes too well, I needed to add the cable as light kicking was causing it to close before I wanted.

    The valve is the standard Sthil type saw valve that is used in everything from chain saws to Harley Davidson V-twins. It has a detent that engages in the closed position to assist closing and keep it closed. This is the specific valve recommended by the Cr500 community.

    Also the valves themselves are only $12, so if needed can be replaced (or spares kept) cheaply.
    #53
  14. PSchrauber

    PSchrauber Been here awhile

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    Ahh kind of semi automatic
    #54
  15. robertr6

    robertr6 n00b

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    Would you be able to make the spacers and mounts? I have a cr500 engine and I think I may be able to get my buddies blown up 08 xcf for a reasonable price. If so, what would the price range be??
    #55
  16. jar944

    jar944 Been here awhile

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    Sorry I don't even have enough free time to work on all of my own projects.

    average price on a blown rf4 is about $1000-1500
    #56
  17. flying frenchie

    flying frenchie n00b

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    Hi.i m doing a cr500 ktm project too. 94 engine with a sxf 450 2008 frame. It s welded painted put together almost completly. I m waiting for the air boot and griphics. I notice that the cdi u r using ( the part attached to the frame and connected to the spark plug) is not the original one and fit perfect on the frame mount. Where does it come from? Also my brake pedal is a little too close from the case, did u have to bend it too? I really like ur blog it help me a lot on my builng. I should have it running next week end. My engine was nothing like urs, just did top end. I also have different radiators, from a xc i think, so i ll run some different hose and use the two holes on the head. I didnt have to mod much the pipe and silenceur either. Lucky on that one. Thx
    #57
  18. Twin-shocker

    Twin-shocker Long timer

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    There is no real need for a lever at all surely? Guy I know uses chainsaw de-compressor valves on large capacity 4T MX bikes, and once the valve is set it closes automatically when the motor starts.
    #58
  19. jar944

    jar944 Been here awhile

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    The compression is so high it closes the valve before the bike fires. I could modify the valve to stay open longer however I wanted a lever to remove the need to "find" the decomp every time I want to start it. It also makes bump starting after a stall very easy.
    #59
  20. jar944

    jar944 Been here awhile

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    You mean the coil (not the CDI) the coil is the stock KTM, with a 2t plug cap.

    Yes the brake pedal was bent out a couple mm to clear the case.
    #60