KDX Top End

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    Table of contents
    1. 1. Wiseco Information
      1. 1.1. KDX 200
      2. 1.2. Top End Bearing

    The Kawasaki KDX 200 or 220 looks like a realy good fit for a Vespa topend conversion due to stroke and bore being almost the same. However, there is quite a bit of modification to do to the cases due to the height that the cylinder sits on the PX cases. The 220 is a lot harder to come by so we chose the 200. If we have to go bigger we may be able to get a 220 sleeve and do some porting. Another alternative is oversizing.

    Scooterhelp talk about it for Lambretta's (Kawasaki KDX200 Cylinder)

    The KDX also has a bigbore kit see: 240 Big-Bore Kit for the KDX200

    JustKDX info 

    KDX dyno (note this may be an old KDX)

    KDX forum

    Wiseco Information

    Wiseco Pistons etc

    KDX 200

    With the KDX crank the 200 is 198.51cc, with the Vespa 60mm long stroke we end up with 205.35cc.


     Model  Years  Bore
    Ring Set
    & Clips
     Top End
    Gasket Kit
     Top End
    Seal Kit
    Rod Kit


    Electrofusion Bore - Cylinder
    sleeving or replating required
    for oversizes.

    1986-06 66


    The biggest we can go in the 200 is 68mm bore = 217.99cc (with 60mm Vespa long stroke)

    For the 220, bore 69-70mm = 224.45cc-231cc (with 60mm Vespa long stroke)


    Top End Bearing


     Part #
     Inside Diameter (mm)
    Outside Diameter (mm) Length (mm)
    B1008 16 21 19.5

    Both the wrist pin of a Vespa PX and KDX are 16mm, so a KDX piston can be used on a Vespa conrod (with a Vespa topend bearing).

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    Comments (6)
    Viewing 6 of 6 comments: view all
    Regarding the comment above on the smallend bearing, would the outside diameter match the conrod, and inside the wristpin so theoretically a px one would do if a standard crank was used.- Ive got a yz125 topend Im trying to graft on to smallframe casings,the smallend is the current hurdle I'm facing as the vespa wristpin is 15mm on the smallframe.( feel free to edit or delete)
    Posted 23:35, 7 Jun 2008
    Thanks. I've fixed up the error. I'm running a KDX piston on a standard(ish) Vespa crank, with a standard Vespa smallend bearing.

    It should not be too hard to locate a smallend bearing of a sensible size. It was pure luck that the Vespa one fitted, however they come in all sizes and thicknesses. Check out the Comp-PinsClipsBearings.pdf as a starter. A bearing shop after that.
    Posted 07:14, 9 Jun 2008
    hello mR. internet scooter...i was wondering....of u wanna do a top end conversoin, what are the points to take note...is it the displacement???and how does the powervalves work on vespa??
    Posted 13:58, 30 Oct 2008
    finding something that suits the current crank is the main issue (just to start with).

    We were testing the power valve last night, we just had it set in either position and have decided to leave it in the high rpm power. At this point we think that is fine, the gearbox is sensitive, so it doesn't make sense to strain it taking off. On a drag bike, though you'd want to get power in both ranges.
    Posted 21:41, 30 Oct 2008
    If u dont mind asking, what is the status of the motor..?!how reliable is the motor??U guys really inspire me to do a conversion my self but not LC cylinders.im still looking for the right barrel to do the conversion...All the best to u guys!
    Posted 13:56, 16 Mar 2009
    Motor is up and running and racing. We don't have the correct pipe for the KDX so we aren't getting the fulll power and where we want it. I'll be writing up an article for Scootering Mag with the results of the Salt Lake racing :)

    It is VERY reliable - we have purposely built up the power slowly to make sure we don't break anything (and if we do we fix the problem before more power is added). For example if we slip a gear, we break the gearbox, so the first time it happened we strengthed the springs on the gear selector to stop it happening again (which worked).
    Posted 21:39, 29 Mar 2009
    Viewing 6 of 6 comments: view all
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