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TKART magazine Under Review | BLACK ROCK: the new LKE engine for KZ
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Max Bernardi
26 January 2019

Like most kart engines on the market, the RKZ is a 2-S. 4-stroke engines are still a small niche

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125 cc

125 cc. Is now the standard cylinder capacity. 100 engines are a thing of the past.

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Push-mode as in all KZ engines, with hand-release clutch and neutral to 2nd gear shifting

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The RKZ belongs to the gearbox “family” of karting engines.
It has a 6 gear manual transmission


It is that of the KZ gear kart, valid from 2019 to 2021

The new engine of LKE Engines, presented in the 2019-2021 approval session, is called Black Rock, designed for gear class karts. This is the first project entirely managed by engineer Roland Holzner on his return to LKE

The name Black Rock reflects the new eye-catching colour, with black details contrasting with the fluo orange plastic clutch cover. The engine was the result of the analysis and development of the previous LKZ1 model carried out entirely by Roland Holzner, the engineer who in the past played an important role in the design of the engines of LKE Engines and who recently started working for the company again. "Before starting a new project - says Holzner - it is important to understand the strengths and weaknesses of the old approved engine: to analyse every aspect of the engine, to hear the drivers' opinions, to see it running on the track and on the test bench, as well as checking all the component drawings".
Based on this detailed analysis, homologue Holzner decided to intervene mainly on the gearbox, thermal unit and cylinder for the new approval. In particular, he introduced the new desmodromic gearbox, already developed by the engineer in other projects, which has made a reduction in the size of the engine possible. The desmodromic was a key point to rethinking the development of all the engine’s components: placed in the lower area of ​​the engine, it has better lubrication that favours the smoothness of the forks. These, in turn, were redesigned, increasing their mechanical strength.
The small size and compactness of the new LKE engine is immediately striking
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The Black Rock project is completely new and has retained few details from the previous LKZ1 engine
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Several plates have been built into the cylinder to dissipate the heat
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The front area fins of the crankcase are designed to maximize the impact of air and reduce temperatures
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In addition, the pin is no longer an integral part of the fork but instead rolls along the desmo track. As far as the latter is concerned, LKE opted for a cylinder with a wider diameter, which allows a lower angle of the tracks and makes the movement of the forks more fluid, improving gear changes. Again, in regard to the transmission, to underline a primary variation: the ratios were increased from 17-67 to 19-75, with the intent of decreasing the friction of the gears and improve performance. Bearing in mind that the gearbox is the main source of heat in the crankcase, at the design stage we tried to separate its location from that of the crank: the passage of water starts from under the gearbox to cool the hottest area of ​​the engine’s crankcase, lowering the temperature and improving the engine’s effectiveness. Instead, the water channel does not reach the front of the crankcase, precisely because, passing first from such a hot area, it would end up bringing hot water, heating rather than cooling the area.
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