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Tkart magazine

Under Review | Screamer III: shift of gear for the shifter engine by IAME

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25 August 2019


Like most kart engines on the market. 4-stroke engines are still a small niche

125 cc

In karting, gearbox engines have always been 125 cc.


The usual one, push-start with manually controlled clutch and start in second gear.


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

KZ 2019-2021

It is the shifter KZ, valid from 2019 to 2021.

With the new 2019-2021 homologation cycle, IAME takes the opportunity to make a clean cut with the past in the design of the Screamer III, the engine for the KZ category. Performance research and ease of use go hand in hand with the objective of achieving better overall performance.

The innovations which characterize the brand new IAME gear engine are many and striking even at a first glance. For example, in the front part of the cylinder one notices what at first sight may seem like cooling fins. In reality, they are “ribs” having the function, thanks to their curved profile, to provide the right structural rigidity to the entire cylinder block.

The cylinder is the component in which IAME has concentrated its attention in the manufacturing of the Screamer III. Completely redesigned, it offers cooling circuit channels that have been studied with an extensive use of CFD (Computational Fluid Dynamics) software. The technicians’ objective was to obtain a more uniform flow of water inside the cylinder and, above all, directed precisely where it is needed

To obtain this result, it was decided to reduce the sections of the double cooling wall that, consequently, contains less water which has the advantage of a quicker replacement of the same water in order to allow a more uniform disposal of the heat. An even more important factor in a vehicle like the kart in which the water replacement takes place through a pump whose capacity is connected to the rotation speed of the axle.

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