They have 0-100 km/h acceleration comparable to a Supercar, front brakes and gearbox: we are talking about shifter karts, the highest class in karting. Taking them to the limit is not at all easy, so we asked the 2020 KZ World Champion for his adjustments to guide you in the best possible way
THE ADJUSTMENT OF THE CLUTCH LEVER
“The clutch plays an important role in starts, its ‘detachment’, when the red light goes out, can make the difference between a good start and a bad start. Care must therefore be taken not to adjust the lever so that it is too far from the steering wheel: your hand must be able to easily manage the entire stroke of the lever during the release phase. If you have more than one chassis, I recommend understanding the detachment point thoroughly and replicating it on all the chassis you use. This will allow you to know exactly when to release the lever when starting a race. If, on the other hand, you only have one chassis, remember to reset it every time you remove and reassemble the engine. As for me, I adjust the lever stroke to 7cm, in the middle, so about 3.5cm is the point where the clutch starts to release. The clutch stroke must always be checked before the start of the race, especially if you change the engine: a few millimetres of difference at the point where it detaches are enough to make a bad start”.
THE POSITION OF THE SHIFT LEVER
“The gear lever must be close to the steering wheel, therefore comfortable to reach, but at the same time it must be sufficiently distant to allow you to steer the steering wheel without touching it with the back of your right hand. In order to adjust it, I adopt the two-finger rule: it is the reference point that I give my mechanic when assembling the engine. In practice it is about 4 cm away from the steering wheel, a measure that, like the clutch lever, is quite subjective, but which must always be carried out on all the chassis I use to always have the same feeling while driving. After adjusting the distance of the lever from the steering wheel, it is important to check the angle that is formed between the lever and the rod, which must be 90° to have an optimal shift. The correct angle must be recorded when fastening the lever to the chassis: the Formula K EVO 30 chassis has a support adjustable in three positions”.
CHOKE THE RADIANT MASS
“The radiator curtain is important for the correct operation of the engine temperature. During the warm-up lap, before the start of the race, I close the entire curtain to heat the cooling system water as much as possible. When I line up on the starting grid, I position the curtain under at the middle of its stroke, which allows me to manage the tussle of the first laps without having to spend time opening and adjusting it to avoid inadvertent overheating. After 2-3 laps I lower the whole curtain depending on the water temperature. With KZ engines, the ideal is to stay between 48°C and 52°C, so if I am just a few degrees out of this range, I try to reach it by decreasing the radiant mass exposed to the air. The temperature must be checked on the dashboard at least once per lap, I do it on the straight, when I can afford to take my eyes off the track for a few fractions of a second”.
In 2-stroke kart engines, the temperature of the cooling fluid is a parameter that must always be kept under control to optimise performance and maintain reliability. With Marco Malverti, owner of New-Line Racing, we explored the topic in the article ”Kart radiator: how to manage low temperatures with throttles”.
“When the engine is about to reach the optimum operating temperature and the radiant mass is completely covered, care must be taken to lower the curtain gradually. If this does not happen, there is a risk of cooling the engine too quickly and suddenly altering the expansion of the cylinder, consequently causing seizure”.
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