I did intend to do a back
to back comparison of the other jetting products available
but I met with some reluctance from the other software
vendors. You may draw your own conclusions as to
the reason for that by the time you reach the end of my article
but I will say that I have tested the others so I do have
knowledge of them, I just haven’t included them in the
The first thing you realise
when talking to John is that he is passionate about his product.
I deal with students with
learning difficulties so I like products to be fool proof,
so that if I try and be as awkward as possible with something
and it still works, then practically anyone can use it.
Jet-Tech is such
a product. There are helpful notes available on screen
to guide you through the various stages towards obtaining
the correct settings on your carburettor.
If all else fails, you can
rely on John to talk you through calmly and easily over the
telephone or by E-mail.
Included with the basic
product is a section for the setting up of different carburettors
other than the Dellorto, so whether you have a Tillotson or
a Walbro or something else on your engine, help is at hand.
Also included is information
on gear ratios and conversion tables for fluids etc.; also
included is a section on tyre temperature analysis.
A section for recording
your chassis setup and weight distribution is another aid
for the karter that is included.
My only small criticism
with the help files is that you cannot print them out and
refer to them as you negotiate your way around the screens,
but it is a minor point and it can be got around if you know
how. However there is a built-in notes feature which allows
you to make you’re your notes / testing diary at the
track which you can print out on your return home.
Much of the information
you would need at the track can be found on the CD.
How the software works.
The most essential thing
you need to go with the software is a weather station that
has barometric pressure and humidity include in its functions.
These are available from
or from the Internet.
Once you have set up and
calibrated your weather station for your height above sea
level your weather station data is ready to be entered into
This gives you a starting
point for jet size and needle settings.
The thing to remember is
that no software can give you the absolute correct information
Engines vary and carburettors
vary, so to arrive at the ideal setting, you have to work
a little bit.
It is this work
that suddenly makes the penny drop and you understand what
you are doing and more importantly, WHY.
That is where John’s
little sliders on the screen come into play.
Those mystical phrases like
Air Density etc start to become apparent and have some meaning.
By reading the help files
and notes, you begin to understand exactly what the problem
is with the Max and more importantly, how to resolve it!
You will find yourself
saying things like, “Oh is that what that’s for,
now I understand”.
Once you have got it right,
the software allows you to save all your hard work and be
ready to jet up the next time you are at the track without
starting from scratch again. Just as soon as you input your
weather station data, the software presents you with your
jet and needle settings.
The amazing thing about
John’s product is just the sheer amount of work he put
into its development and continues to do so.
It is not just a
glorified Excel spread sheet. It is a lesson in getting you
to understand carburetion.
He has included not just
the normal float, jet and needle options, but you will find
settings for needle types etc that you never even knew existed,
such is the comprehensive nature of the product.
If you run ‘non MSA’
then you can also use half clip needle positions by using
a washer under the circlip, as the software allows adjustments
of such small increments. This allows you to get between those
stages from one jet size to the next, more accurately.
Hitting that ‘sweet
spot’ where your engine sings sweetly and pulls
through the rev range without that annoying popping or bogging
is very satisfying.
Just remember that all the
other bits on your engine like the power valve, pulse pump,
reed block and exhaust have to be in good working order to
get the best from this product.
You will also learn how
to read your plug and piston crown colour and to look at the
exhaust header colour and interpret what is going on in the
How many times have you
heard people say that they only run the 168 jet size that
came with their engine and it goes alright?
Sure it goes, but only when
the weather exactly matches the conditions for running a 168
jet, which isn’t often. The rest of the time they are
losing out and probably sitting somewhere near the back of
Just think of how much money
you spend on stuff that ends up in the bin. This software
will be with you long after that £120.00 set of worn
out wets have rotted away and you don’t really bat an
eyelid at buying them, do you?
I am very careful where
I spend money in karting, as there are many things you can
buy that are purely eye candy, blingy and unnecessary.
I am therefore usually reluctant
to recommend any products.
But if you want to understand
how the Dellorto carburettor works, I cannot think of a better
way to learn than to try JET-TECH. It’s an investment.
Review by Alan Reynolds.
on Jetting for Rotax>>