|Carburetion karting is one of the
stages of development more important in practice and race. Indeed
all major categories karts use 2-stroke engines that
as is known they have performance greatly influenced by the
As jetting the kart, what is the carburetion
best for its own engine, which carburettor calibration is more
suitable when there is hot, when there is cold, on a track, for a
pilot, etc. are all questions that always you will come across on the
karting tracks all over the world.
Let's figure from a technical point of view the problems that
we meet in the jetting of the kart and therefore as
move to get the best result.
In karts are used two types of carburetors, those in
diaphragm used in KF categories and in certain brand (X30,
Super Rok, Easy Kart, Kart Champion, BMB, etc.), And those with float used in KZ1, KZ2, MINI 60, 60 and single-brand BABY
Vortex Rok, Rotax, etc.
Carburetors diaphragm are easier to manage, but also less
accurate, while those with float have many elements of
calibration and therefore have a more difficult to manage, but allow to
better meet the needs of the engine.
In fact all part by the needs of the engine, according to its
characteristics, the engine speed, throttle opening, will need
of appropriate amount of the mixture to obtain the best in any
situation and this must be able to do the carburetor.
HOW JETTING THE KART
To jetting the kart is necessary firstly to have method.
Basically there are two phases:
Neither of the two phases is easy, but as the saying goes, those who well
begun is half done, then we should spend some
days of testing in the first phase and from there start to the second phase.
- the first to find the jetting more suitable at the engine that we use
- the second to know how
adjust the jetting to atmospheric conditions,, to the needs that every track demand and to driving style of the driver.
The first important thing to do in the test is avoid to broke the engine, then you have to start in safety, with a jetting
rich and from there begin to lean, and already here began the first
problems, how to lean, at full throttle, at idle, in the passage, by acting on such
elements, etc. are all questions to which we must respond.
It then proceeds by trial evaluating from time to time the
result. Obviously the lap time and the feelings of the driver
are the first elements to which you can refer, but from a technical point of view
you can help yourself to understand how far you are with
jetting of the kart, analyzing spark plug and piston. This also
of course it requires knowledge and experience, moreover with the current gasoline
these readings are increasingly difficult.
Another help to evaluate the carburetion of the kart, you can
have from data acquisition, applying sensors to see the
level of detonation, and the temperature of the exhaust gas, while
the use of the oxygen sensor unfortunately in the 2-stroke engine is not
very reliable and is likely to provide guidance incorrect.
The analysis of the data detected by the knock sensor allows
monitor reliability, while that of
temperature of the exhaust gas, the performance. In this case too
specific experience is required because there are no values
standards for detonation and temperatures to be taken as a reference,
but each engine based on the characteristics, the chamber
combustion, the advance ignition, etc. works best on
However, the analysis on the lap of these values regardless of the
levels can help you understand the behavior of the carburetion of the kart in the different conditions of engine operation.
To summarize what we have seen so far, both the old methods (ear,
spark plug, piston), both the results of the sensors (detonation,
exhaust gas temperature) with adequate knowledge and experience can tell
us where we are and in what direction we should go, but what
unfortunately they can not do is tell us how to change the
jetting to achieve the goal and then have the carburetion
that doesn't detonate, which doesn't damage the piston, which makes
beautiful the spark plug, and that makes us have to exhaust temperatures
that make the engine go fast.
To act on jetting is therefore important to know the
carburetor and know each adjustment element that effect produces
on carburation in the different operating conditions. Seen
the carburetor now existed for more than a century (end '800) you can find a multitude of publications that provide a
simplified explanation of the function of each element of
This can certainly give an idea of the different functions, but here
we are talking of races, competitions, to get the most
from your kart, so you need to go further, learn
the entity of the effects of each element, such as the different
combinations of the calibration elements do meet the
carburetor in acceleration, the passage, at full load, etc.
It's clear that to go further, in addition to knowledge,
we must do so much, but so much, specific experience of each model
carburetor. In fact, as long as we talk about carburetors diaphragm
with only two screws to adjust or at most a few diaphragm or spring from
try, this may be easy, but when we look at
eg carburettors used in karting in 60 MINI (Dellorto PHBG18) or
in KZ (Dellorto VHSH30), the calibration elements become 10 and 12
with respectively 26 and 115 needles, 12 and 38 atomizers,
4 and 7 throttles, and so on for the other elements, and this,
playing a bit with numbers leads to well 14976 calibrations
possible for PHBG18
and even 764750 for VHSH30 ... it seems
incredible, but it's true ... on the contrary in the calculation we have even
neglected the floats, the heights of the float and half notches
... do some of you!
It 'easy to see how to front of these numbers, as well as having the
appropriate knowledge, to accumulate experiences test after test, and
essential to have a technological help to get to the choices
Optimal quickly and confidently, in fact without help, even a life of tests not
It would be enough to ensure that you have found the best setting.
Fortunately, in recent years the technology so far confined to other
stage racing has arrived to the much
reviled carburettors used in karting and so have been developed
specific software to allow you to obtain the maximum the carburetor potential, helping significantly
choose among the infinite possible combinations of jetting
to obtain the maximum performance of the engine kart in all
Obviously when it talks about to software technical we need to see
what can the software, and especially how it does, because
if you really want to get some help for the jetting of kart
from a software, the software needs to be able to keep count of as many things as possible and in the best way possible.
The software for the jetting must in fact be able to
help in both phases we said above, that to
search the optimal calibration for its own engine,
helping the mechanic to skim the many possible combinations and
choose the setting that not only allows you to get to the carburetion
that best meets the ear, the spark plug, the piston, data
sensors, but it is also the best for performance and reliability
of the engine, for good joy of
driver and team!
In addition, the software should help significantly in the other
phase, which is even more important, because it is the one that leads to the
end result, namely the management of jetting kart
in each w.e rac,e depending on weather conditions, the
characteristics of the track, and the driving style of the driver. here
it must help the mechanic to be faster and more precise in the
choices, because as you know sometimes it's the detail that makes the
In conclusion, it appears evident from what has been written that to come
the best jetting of kart, serving different components,
First the method of working, in the second place a software
professional who joins the knowledge and
experience to speed up, simplify and optimize the
choices of calibration to be done, and finally, a good eye and some
sensor to have always under control the behavior of the engine. without
one of these components will always be limited in the potential
and they will continue to hanker after jetting in the box without knowing
exactly what you are doing and thus not accumulating ever
the right experience.
Continuing the reading you can start thinking of putting a
important step for the growth technique of your team and of your