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TKART magazine Under Review | Vortex - ROK DVS towards the future
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04 February 2016
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2 Stroke (or 2 Cycle) - like the vast majority of kart engines; 4 stroke, engines (4S) are a small niche

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125 CC

Today125 cc is the standard value;
100 engines are a distant memory of
bygone days

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One of the most debated topics of the past few years. DVS goes for less is more: no electric starter

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There are two great “families” of kart engines: non-shifter and shifte. The DVS belongs to the first.

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Engines destined to one-make categories are subject to the rules of their dedicated championship

Simplicity. This is the key value behind the new Vortex-ROK DVS engine, which anticipates many of the solutions set to be officialized at the next CIK-FIA homologation with the new OK formula

As of next year, according to federal CIK-FIA guidelines, OK engines will replace the current KF formula in all international race events.
The new name of the game is direct drive with push start, aided by a decompression valve in the cylinder head.
The majority of karters will be introduced to the innovation next season, but drivers who race in the ROK Cup, the one-make series powered by Vortex (OTK group), have already had a chance to try an engine that is a close relative of the new OK. In fact, the Super ROK category has introduced the first engine featuring the new decompression valve system: the DVS. The basis remains the KF, characterized by tried and tested components and validated by a consolidated economy of scale; but several elements and solutions have been changed in a twin spirit of necessity and innovation. TKART has had a chance to analyze the DVS in detail; we opened it up, took photographs from every angle, and talked with the technicians who developed it, getting a good sense of the kind of engine it is.
Let’s start by saying that while we like many of the solutions featured on the DVS, we also we have our doubts regarding others. Then again, for now the DVS is reserved to an adult category, not a junior class, so drivers are able to compensate for some of its limits.
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The blue component on the exahust side of the cylinder head is the decompression valve. Here it is in “closed” mode.Below, a shot of what happens inside the engine when it shuts off. The decompression valve in the “open” position.
In conceptual terms, the DVS aims for simplicity, eliminating all components that are not strictly necessary and that are subject to quick tear-and- wear and easy breakage, with an impact on overall costs, namely: the clutch, the water pump and relative mechanisms, and the electrical starter and the annexed 12 volt battery.
All gone!
This inevitably begs the average karter’s question: so how do you get it started? Like back in the good old days of 100cc direct drive engines: by pushing. The catch is that today’s engines and chassis are heavier (displacement increased to 125 cc and bigger and more complete body fairings, especially in the back). So, to make the start easier, without having to lift the rear end off the ground, a decompression valve has been added in the engine head.
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