RACING LINE - KF - 100cc - Rotax Max

The new CIK-FIA certified chassis for the 2009-2014 period will be: versions RY 30-S1 and RY 31-S1 Alongside of these will be the tested RX 32-S1 (with certification valid until 2011), that is more advanced compared to the past season.

The three models available for the KF classes have features that are often complimentary so that, in a competitive environment, almost all teams make at least two versions available to their drivers. That is in order to find the best productivity regarding the tires used, the conditions and the configuration of the track. Let’s look at the principal features of each of the Birel KF models for the 2009 season.

All of the 2009 models have a series of “large” front spindles with a diameter of 25 mm, characterized by the possibility of varying the shaft (varying the materials) by using a specific key that is supplied with the kart. The versions with front brakes have the steel action lever housed on the steering wheel hub, while each chassis has a series of new adjustable machined footrests.

RY 30-S1: the body is made of 30 mm pipes and is characterized by a front axle design that has the “C”s of the spindles anchored to the front crossbeam. Also in the front zone there is a single torsion bar. It is especially advised for use with soft tires and on rubberized tracks. But, due to the torsion characteristics of the body, it is also very effective in the youth classes (for example the KF3) where, usually, hard tires are used. Ending up very “free”, in fact, takes the best advantage of the limited power of the engines used in these classes. The removable 4th bar next to the seat is also functional in this sense.

RY 31-S1: the body cross-members are built with 30mm pipes while the crossbeams are 32 mm. The profile is a recalculation of the previous model R 31 with the spindle “C” anchored at the height of the largest torsion bar where the cross members meet at the front crossbeam. Also in the front there are two usable torsion bars, with the larger one acting on front end behaviour and the smaller one increasing the rear axle grip. This model is an excellent compromise for versatility, adapting itself very well to both soft and medium-hard tires. Its strong point is its excellent fluidity and the general balance between the front and rear ends.

RX 32-S1: the body is entirely built of 32 mm diameter pipes. The design is very similar to the RY 31-S1 version with the only difference being (besides the diameter and some technical specifications of the pipe) that there are two bends in the crossbeam in front of the seat and the one behind it. This model is particularly advised when grip is needed, thus for barely rubberized tracks, low temperatures and with the use of mediumhard tires.

Novelties for 2009
Among the most significant novelties introduced with the new certifications is the new model RY 30-S1 (made with 30 mm pipes). A conventional one, it allows the driver to easily find an excellent set-up offering excellent performances for all uses: from the youth classes up to the top categories. On the other hand, models RY 31-S1 and RX 32-S2 are advanced in comparison to the previous certification. Both versions were updated, especially concerning the technical specifications of the pipe. Among the prerogatives and the equipment common to the entire line, there is the removable 4th pipe at seat height (removing it “frees” the chassis at the rear axle while more grip is guaranteed with it in place) and the new “large” front spindles with a diameter of 25 mm characterized by the possibility of varying the shaft (with material alternatives as with the axles) using a special key that is supplied with the kart. The housings used are the “FL 09- 14” (with new graphics) that maintain the aesthetic lines of the previous ones but that were optimized with their weight reduced by about 1.3 kg. Finally, on the entire line, there is an HQ exhaust support in order to facilitate mounting the rear housing and a new machined foot rest.

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