Any changes on port layouts over the years?

[internetscooter]

I am thinking about converting the top end of a Vespa PX200 (scooter) to a KDX200. As part of my investigation into whether or not it is possible I have bought a 1986 air cooled top end off **** for $30 just to see it in the flesh. The final conversion I want to do will be a water cooled KDX (so 1990+), and I am wondering how close is the aircooled head dimensions and port layout to the water cooled?

 

[duke]

What is it that incites you to undertake such a project? Does the Vespa model series you quoted possess some porting specs making it worthwhile? I mean I am quite ignorant about Vespa's, other then a lot of local college kids rely on them for transportation.

 

[chicoman]

I am guessing they're a lot different, if your aircooled head has a powervalve it will be a lot different than the new kdx's. Buy a base gasket for the head you wish to install and see if it everything lines up with your current botten end. Will the power valve linkage line up? is the stroke and connecting rod length the same? How will you make the pipe fit? This project may be close to impossible.

 

[76GMC1500]

The port timing doesn't need to match. The port timing is what seperates a Vespa from a KDX. You want the port timing to be different or there would be no point in making the swap.

 

[chicoman]

The port timing doesn't need to match. The port timing is what seperates a Vespa from a KDX. You want the port timing to be different or there would be no point in making the swap.

This is true. Why dont you see if an engine tuner can change the port timing of your vespa to match that of a kdx, then fit a kdx carb and get an fmf pipe to fit. This may be expensive but at least it might be possible. On second thought the ports on your vespa are probably so much smaller that there isn't enough metal there to work with. One more thing, Can the Vespa cooling system, clutch and drivetrain handle the extra heat and power?

 

[internetscooter]

Sorry - original question has been missunderstood ;)

The Vespa ports and KDX ports a miles apart. I am asking if the KDX 200 air cooled casing transfers and the KDX 200 water cooled casing transfers are the same? I have bought a KDX air cooled head just to see how much work I need to do to my Vespa casings. If the different KDX versions are very similar or the same then the head I am getting is a good test.

The reason I am trying a KDX conversion is Vespa kits give me about 16-20Hp and are prone to blow up. A KDX top end should give me a lot more and be more reliable (excluding any bottom end problems). Also apart from the major rework to the casings, the KDX should be cheaper to build and maintain.

If you google for-> scooterhelp "Kawasaki KDX200 Barrel" <-you'll see what I am on about. They talk about it but I don't think anyone has actually done it for a Vespa.

 

[76GMC1500]

Grinding and epoxy will make the ports match.

 

[arjay]

Visually the 86-88 aircooled cylinder ports look very similar to the 89-94 watercooled ones (Transfers and intake)