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Valve …forever!

Rotating disc engines have disappeared from the karting world for around 15 years. What decreed their end? Lamellar’s technical supremacy or a set of political and commercial reasons? What would a “valve” be like today? It is still worth talking about…


The unstoppable ascent of the 2-stroke engine in the world of competitions, especially motorcycling, occurred in the 1950s when Walter Kaaden of MZ was able to produce a mechanical stratagem to obtain an asymmetrical intakediagram with respect to the movement of the piston in combination with a strange exhaust pipe that used the waves to provide the engine with a sort of supercharge and improve the volumetric efficiency. We’re talking about the rotating disk and the expansion exhaust. The latter we thoroughly discussed in the latest issues of Vroom, so it came naturally to think of dedicating a few pages to the rotating disk intake, for years also protagonist in our sport and then set aside for a series of political and commercial reasons that have little to do with technical matters.

While compiling the data sheets of the engines of the last homologation I noticed that, in practice, the only differences now are at the level of the interaxis of the piston rod and cylinder tilt-angle as they are all 5 transfer ports with elliptical exhaust and additional boosters according to the Rotax / Honda scheme, bore and stroke 54x54mm and lamellar intake in the crankcase with horizontal pakage. The difference, with all the limitations due to an extremely restrictive regulation, above all makes the tuner and the manufacturer able to provide a robust, fluid, dynamically evolved and mechanically perfect engine. The last engine that proposed a different solution was the Maxter MXV with vertical lamellar package, which in practice no one has developed even if I personally would bet that on some very fast tracks it could have held its own. Today, however, the byword is not to take risks. To make the original engine at any cost and then find oneself with 50 unsold pieces in the warehouse takes an instant, just as takes an instant to find yourself closing up shop and packing it all in…

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About Vroom International

In this issue: Fair for fun The 2019 edition of IKA-KART 2000 in Offenbach, the unmissable exhibition for kart enthusiasts, aimed above all at leisure karting more than racing X-RAY TM 125 KZ-R1 THE WAY WE WERE ROTATING DISC ENGINES INTERVIEW GIANCARLO TININi Focus G Line Accessories WATER TEST 7 PUMPS COMPARED I love kart GEORGE RUSSELL EMILIANO CYRUS LEGENDARY KART FAYE ‘LADYBUG’ PIERSON