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Thread: DD 1200 Engine Rebuild, New undercut gearbox. Need any pointers on what you would do.

  1. #16
    apriliaforum prov-nov
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    thats a fair bit of engine mods going on there! does undercutting improve performance?

  2. #17
    apriliaforum prov-nov Mattix415's Avatar
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    Quote Originally Posted by truck View Post
    thats a fair bit of engine mods going on there! does undercutting improve performance?
    Hey man,
    Well new rings and seals should give me a little boost and also the exhaust being ceramic coated and heat wrapped will give a few HP. Also i did chop out the cats so the bike is going to be stupid load with the Arrow cans but hey load pipes save lives!

    The under cutting will just make the gearbox take more load and have less chance of stripping the dogs on the gears. basically the more power the tighter the gear sits in the dogs.

  3. #18
    apriliaforum prov-nov Mattix415's Avatar
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  4. #19
    apriliaforum prov-nov Mattix415's Avatar
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    Head was removed off one cylinder and it looks like the stock pistons are actually billet pistons and not cast iron. Which is very interesting as they are 106mm which is massive! Looking forward to getting down to the crack to see what the conrods are and if they are any decent on these engines.

    Going to get the walls deglazed, after 40 000km they are not in bad shape but will need a deglaze in order to seat the new rings nicely.

  5. #20
    Honest always, feared often Micah / AF1 Racing's Avatar
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    Stock pistons are forged aluminum, the final machining is done with CNC though which gives that billet looks. You would probably not want billet pistons as they would contain a metal grain structure very undesirable for uniform expansion as the piston heats and cools. The cylinder walls are Nikasil plated (nickel, silicone, carbon) plated aluminum alloy, piston rings are steel. At 40k miles there really should be no more wear than perhaps a slight polishing of the thrust surfaces of the nicasil bores, cross hatching should be visible still though they may "Feel" smooth to the touch.
    Diminished expectations is the key to happiness in life.

    Micah Shoemaker
    AF1 Racing
    9900 IH35N
    Austin, TX 78753
    micah@af1racing.com
    @ShoemakerMicah
    @AF1Racingaustin

  6. #21
    apriliaforum prov-nov Mattix415's Avatar
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    Hi Micah,

    Thanks for the comment!

    So then would you suggest i go ahead with the deglazing to get the new rings to sit nice? The cylinder walls are like a satin texture smooth to the touch but there are visible.

  7. #22
    Honest always, feared often Micah / AF1 Racing's Avatar
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    I would just do a VERY LGHT HONE on a sunnen type cylinder honing machine, attempt to hit 30/60 degree crosshatch angles.
    Diminished expectations is the key to happiness in life.

    Micah Shoemaker
    AF1 Racing
    9900 IH35N
    Austin, TX 78753
    micah@af1racing.com
    @ShoemakerMicah
    @AF1Racingaustin

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