Media Coverage - "Dial-A-Jet Fuel Induction - What the Heck is it?" - ATVConnection.com / SnowConnection.com Magazine April 99

The mysteries of carburetor tuning can confuse even the Merlins of engine tuners. How fuel flows through the fuel circuit and gets delivered to its final destination--the combustion chamber--can be mystifying, but through the help of aftermarket gurus, the puzzle can be pieced together and begin to form a solution.

Changing main jets in a carburetor isn't necessarily a question of 'if', but rather a question of 'when'. What we mean is that if you have ever fouled a spark plug in 40-degree weather, or melted a piston in 20-degree-below weather, you have fallen victim to carburetor jetting.

Rejetting a carb isn't that difficult, just inconvenient. When it's below zero outside, you don't want to mess with removing an airbox, loosening clamps, turning carbs upside down and spilling fuel, just to find out after you put it all back together that you should go one size larger yet--and do it all over again.

The Dial-A-Jet Fuel Induction System by Thunder Products was developed to eliminate this scenario and help solve one of those carb jetting puzzle pieces. Just the included tuning manual alone gives so much information about how fuel flows into your engine that after reading it, you should know just how to jet a carb on a two-cycle engine. In fact, Thunder Products has been told by some customers that is is giving too much information, but its philosophy is to educate the people who purchase its products.

The Dial-A-Jet has been around for many years. Invented by Dennis Dean in the mid-'70s, the system was used to win over 120 world motorcycle drag race records. Dennis is an engineer with a Ph.D. in acoustics and wanted to be able to make quick and easy adjustments to his motorcycle carbs. Lonn Peterson, who has over 30 years of powersports experience with snowmobiles, ATVs and motorcycles, saw the potential of improving a machine's carburetion. After getting so much positive feedback from his customers, he decided to buy Dial-A-Jet from Dennis and has turned it into the biggest jetting improvement you can make to a carburetor. Lonn has made many improvements to the basic Dial-A-Jet package to make the system function better, fit better and improve user friendliness.

The Dial-A-Jet is a simple device that bolts to your carburetor and draws fuel from the float bowl, mixes it with air and transfers that mixture into the venturi of the carb. Some carb jetting systems feed raw fuel into the venturi, but the Dial-A-Jet feeds pre-atomized (super-fine fuel droplets mixed with air) fuel. This is important! The reason is that the pre-atomized fuel does not need to be mixed with air--it already is. This results in smaller air/fuel molecules and these small molecules get pushed aside by the larger air/fuel droplets. When this happens, the pre-atomized fuel fills in the lean spots where the larger fuel droplets can't and thus reduces a potential burndown condition and adds more fuel charge to the cylinder for more power.

A question many people have when they first see the Dial-A-Jet is, "What is each position on the dial worth in terms of jet size?" Each hole in the Dial-A-Jet dial does not represent a main jet size nor does it replace your main jet; it simply enhances your main jet circuit, and upon doing so, allows you to run smaller main jets. It's not linear to your carburetor's main jet size. It's automatic.

In other words, the largest hole (which is the leanest setting) will feed pre-atomized fuel based on the engine's needs and fill in the lean spots where needed. In one condition, that large hole setting may feed just enough fuel to fill a lean spot in light engine load application such as accelerating down a trail. In another condition, that same large hole setting may feed more pre-atomized fuel in a heavy engine load application such as riding up a long hill. Both applications use the same dial setting, but one feeds more pre-atomized fuel than the other. This is something your main jet can't do by itself.

Another question that people ask is, "What's so different about the Dial-A-jet compared to other fuel feeding systems for carburetors?" There is no quick answer, as there are so many things that make this product different. The Dial-A-Jet has no electronic or moving parts. This eliminates having to rely on a mechanical part that may fail. Most of these failures occur when you least want them to, like when you're on a mountain side or your buddy's only 1-� quad lengths behind you.

Another important area where the Dial-A-Jet differs is that it works throughout the throttle range, from just above idle all the way to full throttle. Some systems only benefit the top 7/8 to wide open areas and feed raw fuel into the carb. Dial-A-Jet purges your carb's float bowl of water and alcohol, preventing a lean spot in the main jet. For Banshee riders, it allows you to fine-tune your engine one cylinder at a time, as each cylinder may not have the same fuel needs. Dial-A-Jet only adds fuel and cannot lean past the main jet, which means that even at its leanest setting, Dial-A-Jet is adding fuel to the engine.

The Dial-A-Jet system addresses both temperature AND altitude at the same time. One system does it all! As the temperature goes down, you simply click your dial to a smaller hole and that richens your carburetion. As your elevation goes up and air gets less dense, you turn your dial to a larger hole to add more air to the fuel charge.

The Dial-A-Jet has been refined over the last few years, and if you have an older Dial-A-Jet system, you may want to upgrade to a new one. The dials have been changed to a contrasting white color so it's easier to see what setting it is on, the mounting system has been upgraded to the Pro Mount system, where it no longer utilizes the metal hose clamp to mount it, and the fuel pick up system has been refined for a cleaner, easier installation. A Positive Seal Snorkel Kit is available that draws outside air instead of pressured, under-plastic air that can have an affect on the Dial-A-Jet calibration.

As good as the Dial-A-Jet instruction manual is, you won't find a chart of dial settings or jet sizes to use in your particular machine. The reason is simply that there are too many variables that come into play. Even with two identical engines, you may find that they both have a different dial/main jet combination from each other. Adding a pipe, porting the cylinders, the type of fuel used, even the type of spark plugs used can have an effect on jetting. Properly set, you will be able to run at any temperature and any altitude by simply turning the dial on the Dial-A-Jet body.

Watch for further updates on our experiences with the Dial-A-Jet. Some of our staff is already using them with great success.