Accurate Jetting in
Mikuni - Keihin - Dellorto - Bing - Bendix - S&S
- Amal - Lectron - Chinese Carbs
Dial-A-Jet fits any brand, size
of carburetor with a float bowl. If you don't see
your machine listed, just ask!
Dial-A-Jet is like adding fuel injection
to your carburetor that you can richen or lean by turning a dial.
More Horse Power -
Excellent Running Quality
Fuel - Easy
Rejet in seconds with a
click of the patented 5 position jet dial
Allows you to run in a
broad temperature or altitude range without rejetting
compensates for: air density, motor load, and fuel
!!! NOT legal
for sale in California on pollution controlled motor vehicles !!!
except on vehicles used for closed course racing only
or in other states where similar laws apply.
For off-road racing
Not for aircraft use
Sick and tired of changing jets?
Dial-A-Jet will take care of this problem and a whole lot more!
Why change jetting? Some people don't!
Your engine will lose 10% to 15% of total horsepower with improper jetting. A 100 HP machine will make 85 to 90 HP. The simple fact is that changing jets is not a pleasant task and takes a lot of time.
Now you can run at peak horsepower all the time whether your engine is stock or modified. The best part is that jetting is quick, easy and accurate with Dial-A-Jet.
fits any carburetor; Keihin or Mikuni, round slide, flat slide or butterfly,
and is easy to install.
NOT like a Power Jet. A Power Jet feeds raw liquid fuel, just like the other circuits. Dial-A-Jet feeds
emulsified fuel for instant throttle response and works from just above idle to full throttle.
Dial-A-Jet feeds a fine consistent mist of
emulsified fuel instead of raw liquid fuel like all other jetting circuits in your carb.
Pre-atomized fuel weighs 10% of what raw liquid fuel weighs, therefore, it is very responsive to engine needs.
Dial-A-Jet gives you great throttle response. The
emulsified fuel is delivered to the engine instantly and acts as an intermediate circuit until the heavy wet fuel from the other circuits catch up.
Dial-A-Jet emulsified fuel charge fills in the lean spots between the poorly atomized fuel molecules from other jetting circuits eliminating lean spots.
The lightweight fuel charge follows the path of least resistance, a law of physics. This gives you a consistent, even fuel supply at all engine RPMs.
Dial-A-Jet allows you to run at peak HP at all temperatures and
altitudes. No other product does this at any price.
Dial-A-Jet is the easiest and fastest way to "tune-in" any modifications you have performed on your machine. From pipes to porting, Dial-A-Jet makes it work right.
will make it easy to jet a piped engine correctly with less fuel on the low
end for crisp throttle response. Dial-A-Jet will automatically raise
the fuel curve as the pipes kick in, giving you a perfectly calibrated
engine from bottom to top.
Dial-A-Jet is a great protection against burn down due to its ability to feed fuel accurately based on the engine's demand.
Dial-A-Jet consistently purges your float bowl of moisture (water, alcohol or
benzenes) as they settle to the bottom. This eliminates water seizures or burn down, carburetor icing, galling or broken intake skirts on your piston.
Dial-A-Jet eliminates detonation/pinging and compensates for poor fuel quality.
Dial-A-Jet allows you to re-jet your entire engine (single, twin, triple or four cylinder) in about one minute.
Dial-A-Jet allows you to tune each cylinder individually for maximum performance.
Dial-A-Jet improves fuel efficiency 10% to
20% or more.
Dial-A-Jet has no moving parts or complicated electronics. It works every time, all the time.
Dial-A-Jet Tech Article
Automatic Fuel Induction System
Dial-A-Jet is a completely
external jetting system that delivers maximum horsepower from any
engine at any temperature or altitude. "DJ" improves
throttle response and fuel mileage. It works well with stock or
modified engines, standard or high performance air boxes and
exhaust systems. Easy to install kits are available for
snowmobiles, ATV's, dirt bikes, motorcycles and automobiles.
Dial-A-Jet system was invented by Dennis Dean, Ph.D. (Doctorate in
acoustics). Mr. Dean held over 120 world motorcycle drag racing
records and several Bonneville records. The Dial-A-Jet concept was
used on all of these machines. He knew that he needed a different
fuel curve for the launch area, middle of the track and the end of
the track. He also had to deal with different altitudes,
temperatures, and air densities. Dial-A-Jet proved to take care of
these problems as well as providing that fine tuning edge that
meant the difference between winning and losing at this highly
Modern motorcycle engines come from the factory jetted on the lean
side, leaving little room for error. Motorcyclists often discard
their standard air filter and install a high flow air filter. This
will upset the air to fuel ratio making the engine run even leaner
and hotter. Custom exhaust systems are usually lower restriction
which also causes the engine to run leaner and hotter. The
combination of the high flow air filter and the low restriction
exhaust system substantially alters fuel flow requirements,
leaning the engine and raising the operating temperature. The
additional heat that is generated can have a detrimental effect on
engine longevity as well as delivering poor performance. Gear
selection may become more difficult due to increase in oil
operating temperature. The cure for these lean conditions is to
restore proper air/fuel ratios. This can be done by rejetting
which requires removal and disassembly of your carburetors. This
may be a very expensive proposition, paying for 3 or 4 hours of
shop time as well as purchasing a jet kit. Dial-A-Jet kits can
usually be installed at home in approximately 1 to 1 1/2 hours
without having to remove and disassemble your carburetors.
Dial-A-Jet now allows you to richen or lean your engine in seconds
simply by turning a dial. The ability to adjust your carburetors
externally may save you another trip to the local dealer to adjust
your carburetors if they didn't get it right on the first try.
Lonn Peterson became interested in using Dial-A-Jets on
snowmobiles in the winter of 1989/90. Lonn recognized a great need
for this product in the snowmobile industry. Large altitude and
temperature changes had to be dealt with, not to mention engine
modifications requiring attention to the fuel system. They worked
so well and the feed back was so positive that he decided to buy
the company. Lonn and his wife, Ann, now own Dial-A-Jet which is
part of Thunder Products, Inc.
The basic concept of the Dial-A-Jet has never changed since day
one; however, it is a highly evolved product that has seen many
improvements. Performance has always been the number one
consideration. Most other improvements have to do with making the
Dial-A-Jet more user friendly, such as fitting into tight places
or mounting in easy to access areas, filtering the air to the
Dial-A-Jet, reading the settings, etc.
Dial-A-Jet is a very reliable fail proof product that works every
time! Dial-A-Jet makes more horsepower on less fuel. You can
expect gains in the 3% to 5% range. It's much more than a quick
and easy way to change main jets. There are no moving parts or
electronics to fail. Dial-A-Jet is a small product measuring only
7/8" long, 5/8" wide and 5/8" high. Air enters the
Dial-A-Jet body through one of the five pre-selected air correction
circuits in the rotary dial. Each of the five air correction
circuits is a different size allowing either more or less air to
enter the mixing chamber. More air would be leaner (larger hole)
and less air would be richer (smaller hole). Fuel from the float
bowl is instantly drawn into the mixing chamber and swirled with
air at a high rate of speed emulsifying the fuel. The fuel mixture
is like millions of tiny thick skinned balloons with air inside.
This is called an emulsified fuel charge. The emulsified fuel
charge is inducted into the carburetor through the secondary main
jets located in the fuel delivery tube. At this point the
Dial-A-Jet is way ahead of the rest of your carburetor. All of the
other circuits in your carburetor introduce raw liquid fuel into
the air stream, just beginning the atomization process. The
lightweight fuel mixture from the Dial-A-Jet only weighs 10% of
what liquid fuel weighs. Slight changes in engine load can be
quickly and accurately compensated for with this lightweight fuel
mixture. Instead of losing as much as 15% of your horsepower due
to improper jetting, your machine can now perform at optimum level
at any temperature or altitude. A snowmobile will always run like
it does at 20 degrees below zero.
Three things trigger Dial-A-Jet's fuel signal: 1) engine pressure
drop (vacuum or fuel signal); 2) acoustic sound signal which
either amplifies or de-amplifies the reversionary pulse waves of
the intake tract (we will explain more about the acoustics later);
and 3) air flow and velocity. Dial-A-Jet works from just above an
idle all the way to full throttle. Dial-A-Jet automatically gives
you a perfectly calibrated carburetor that feeds fuel linear to
engine load. Feeding fuel linear to engine load means being jetted
properly whether you are pulling a heavy engine load like a hard
hole shot with good traction or just cruising easily on hard pack
at 40mph. Various speeds and engine loads require changes in your
fuel curve. Dial-A-Jet automatically monitors your
engine's needs then alters your fuel curve to match. A load must
be placed on the engine for Dial-A-Jet to function. You can't rev
your engine up on the jackstand and watch fuel go up the lines.
Without loading the engine, there is no need for extra fuel;
therefore, Dial-A-Jet does not deliver fuel. This is normal.
Dial-A-Jet is an add fuel only device. You cannot add fuel to an
engine that is running rich or has an adequate fuel supply and
hope to gain horsepower. You must create a lean condition so that
Dial-A-Jet has a window of opportunity to function. Dial-A-Jet
will automatically fill in the lean areas of the fuel
curve giving you optimum performance. The fine emulsified fuel
charge can't displace the heavier poorly atomized fuel from the
other circuits so it takes the path of least resistance and fills
in the lean mix areas eliminating fuel spiking and giving you a
consistent fuel flow pattern producing stable temperatures and
horsepower. The only way Dial-A-Jet can fail to perform is if you
do not get the carburetor within range of the Dial-A-Jet. This
usually means that the main jet is too large. You must create a
slightly lean condition so the Dial-A-Jet has a working range.
This is typically about three or four jet sizes below a properly
jetted machine. A single Dial-A-Jet will deliver 10% to 15% of
your overall fuel curve in an emulsified state. There are five automatic
fuel ranges you can select from on each Dial-A-Jet. Simply rotate
the dial to raise or lower your fuel curve. With Dial-A-Jet each
carburetor can be adjusted independently. This is a huge advantage
for maximizing the full potential of each cylinder while giving
you great protection against burn down.
Dial-A-Jet is an acoustical device that is triggered by acoustic
sound signals. The acoustic signal is generated when gasoline is
ignited in the cylinder just inches away from the Dial-A-Jet. This
signal amplifies the pumping action created by the reversionary
pulse waves that occur naturally in any engine's intake tract. The
acoustic signal along with normal engine vacuum or fuel signal
causes fuel to be delivered to the engine. We have all heard the
sound of a fat, over-jetted engine such as you hear at high
altitude or very warm weather riding. It's the whaaa whaaa sound.
This is a slow, fuel rich reversionary pulse wave in the intake
tract. This would give Dial-A-Jet a de-amplified fuel signal
resulting in little or no fuel being inducted. The reverse of this
is also true. A crisp lean sounding engine generates a fast sharp
reversionary pulse wave, triggering Dial-A-Jet to automatically
induct fuel. Detonation is an extreme lean condition that
generates a sharp reversionary pulse wave. This excites the
Dial-A-Jet causing a rapid response with additional fuel delivery
to stave off engine damage. Remember that we are moving a very
light weight emulsified fuel charge. This is the reason it is so
responsive to the engine's fuel needs over such a broad range.
Dial-A-Jet works great on stock or modified machines giving a
realistic 10% to 20% increase in fuel economy or more. Throttle
response is extremely fast and smooth. Throttle lag is virtually
eliminated. Throttle lag is where the airflow in your carburetor
out accelerates your fuel, which finally catches up. Being that
the Dial-A-Jet delivers such a lightweight fuel charge, the air
can no longer out accelerate the fuel as it once did. The result
is major league throttle response! Dial-A-Jet automatically
purges your float bowl of alcohol, water, benzenes, or other
unwanted sediments that could cause engine damage. Modified or
piped machines will have fuel needs that require a higher fuel
curve when the pipes and modifications kick in. In other words you
need one fuel curve when running below peak and another fuel curve
at peak horsepower. This is why a piped machine is so fussy to
jet. More horsepower requires more fuel. Dial-A-Jet will automatically
raise or lower the fuel curve optimizing performance. Dial-A-Jet
feeds fuel based on engine demand. Spark plugs will last longer.
The plug color will be lighter and piston wash will be minimal or
disappear due to the improved fuel delivery and combustion
Now that we have talked about Dial-A-Jet having so much automatic
circuitry, you need to know how the manually adjusted dial fits
into the picture. Each of the five positions represents a higher
or lower fuel curve (richer or leaner). It's not a case of
starting and stopping from one position to the next. There is a
great deal of overlap with each setting. For the most part you
will seldom need to adjust the dial. A big change in altitude or
temperature will be about the only time a change will be
necessary. Dial-A-Jet comes with a very easy to understand
installation and tuning manual that explains in detail how and
when you may need to change settings.
The Dually Kit consists of two Dial-A-Jets per carburetor. It
delivers 20% to 30% of your overall fuel needs. This kit was
designed to service engines that have high cubic feet per minute
of airflow. Highly modified engines or large displacement engines
usually fall into this category. Another circumstance where a
Dually Kit is used is for extreme temperature and/or altitude
changes. You can ride in the Midwest at sea level or you can ride
in the western mountain ranges. The Dually provides a very broad
tuning range virtually eliminating the need to change jetting. You
seldom, if ever, need to adjust the dials due to the high
percentage of fuel automatically being metered through
the Dually system.
The Snorkel kit is a fitted rubber cap that goes over the
Dial-A-Jet body. A vent line is inserted into the rubber cap and
routed up the handle bar shaft, exiting just outside of the hood.
A foam filter is attached to this end of the vent line. Cold clean
air is fed to the Dial-A-Jet. This also eliminates belt dust,
snow, ice or other debris from plugging the air correction circuit
in the Dial-A-Jet making it run rich. Problems with under hood
pressure are eliminated. The snorkel is a must for ATV's and dirt
bikes equipped with Dial-A-Jets.
Dial-A-Jet has even been successfully installed on fuel injection
machines. One Arctic Cat dealer wanted to run performance pipes on
a 580 EFI. The existing fuel map worked fine on the bottom end and
midrange; however, the top end was extremely lean. Dial-A-Jets
were installed on the throttle bodies. Fuel was pulled from a
remote float bowl (available from Thunder Products) attached to
the return line of the fuel injection. Dial-A-Jet cured the top
end lean condition. The set-up worked great, yielding a crisp
broad power band! The Dial-A-Jets could be adjusted for
temperature, altitude, engine load, or fuel quality. The
installation was simple and effective. More than 3,500 trouble
free miles have been logged on this machine.
Does your engine require aviation gas or other high test fuels?
Maybe not. Dial-A-Jet can be installed on your carburetors and
used to induct many types of fuels or fuel additives such as
octane boosters, alcohol (methanol), alcohol blended with nitro,
propylene oxide, etc. One of the lowest cost, user-friendly fuel
boosters is alcohol (methanol). This is a very easy and
inexpensive way to raise your octane while lowering
engine-operating temperatures by approximately 150 to 200 degrees
Fahrenheit. Dyno tests have shown a 5% to 6% increase in
horsepower. Installation is very easy. Install a set of
Dial-A-Jets in the conventional manner. Now you will need a small
tank mounted under your hood for the alcohol. The tank should have
a fuel shut off. A remote float bowl with a needle and seat will
also be needed to handle the fuel from the tank to the Dial-A-Jet.
Simply hook the Dial-A-Jets to the remote float bowl and you are
ready to run. This is very simple and effective, it can be used on
any ordinary trail machine to safely boost performance and raise
horsepower while lowering temperatures.
Dial-A-Jet is a very cost effective product. Each kit comes with a
complete installation and tuning manual. Thunder Products provides
full time expert technical support for all of their products.