Product Evaluation - "Dial-A-Jet" - Dirt Wheels 

If you have ever taken your quad far from its usual play area, chances are it doesn�t run quite the same as it does back home.  Altitude, air pressure and temperature can all affect the way your quad�s engine runs.  The most common way to deal with these changes are by adjusting the carburetor.  The carb is the heart and lungs of your motor and all changes in performance are controlled within.  If you have ever spent any time adjusting carbs, you know how much of a hassle it can be.  And some machines can be harder than others to work on (see a complete jetting how-to story in the April issue of Dirt Wheels).  So, when new carb tuning tools are released, we can�t wait to try them out.  The latest one to come across the Dirt Wheels products desk is an item called Dial-A-Jet, from Thunder Products, Inc.

     The Dial-A-Jet system allows you to adjust your ATV�s fuel flow without taking the carb apart or even touching it.  When properly installed, the Dial-A-Jet draws extra fuel into the intake system.  Depending on the engine load, the Dial-A-Jet automatically adjusts the amount of extra fuel that is needed.  The extra fuel is pre-mixed to an atomized state with incoming air before it reaches the carburetor, similar to a fuel injection nozzle.  Also, for severe altitude or temperature changes, the rider can stop the vehicle and make a dial adjustment of about four different mainjet sizes to compensate for the different conditions.  To achieve this, five different sized holes on the dial help additional fuel that is needed in the carb.

Dial-A-Jet units can be installed on the airboot or the carb snout itself, if there is enough room. The closer to the carb, the better it works.  The silver tube to the left of the dial covers the fuel tube if it needs protection from the heat.  To the right is a snorkel system that can be mounted up if you ride in wet or sandy conditions.

INSTALL IT & FORGET IT

     We installed the Dial-A-Jet on our used, stock 400EX that we have been riding for most of the year.  Thunder Products supplied us with a thorough instruction manual and tuning guide.  Installation took less than one hour and didn�t require any special tools.  On the EX, we were required to reduce the mainjet two sizes from a 148 to a 142 and make one hole in the rubber air-boot between the carb and airbox.  This is where the Dial-A-Jet box would be installed using a large Ty-Rap.  Also, we removed the stock drain screw from the float bowl and replaced it with a hollow fuel delivery tube supplied with the kit.  This is connected to the Dial-A-Jet box with a small clear tube.  Through this tube you can also see the fuel level in the float bow..  After the Dial-A-Jet is installed, your fuel flow can be  adjusted externally.

     The Dial-A-Jet works with a siphon effect.  Depending on air intake flow, a certain amount of fuel will be sucked from the float bowl drain screw, them directed and sprayed into the air boot.

JET SET

At our usual testing altitude of 2500 feet, the biggest improvement we noticed was throttle response.  Our stock EX revved up just as quick as if it had a free flowing exhaust system on.  The revs hit the limiter noticeably sooner than before.  Since the product only effects the main jet, idle was not affected.  Out on the test track, we noticed a small increase in mid and top-end power.  The makers claim it is about two horsepower gain.  At this altitude, turning the dial barely made a difference.  An average rider wouldn�t notice a thing.

     Our second test took us up in the mountains to an elevation near 7500 feet.  With the same internal jetting, our 400EX performed fair with the dial at a neutral position.  However, when we turned the dial to full negative (less fuel) the motor performed as good as it did back at 2500 feet.  For example, we turned the dial to full rich and the motor did as expected.  It ran well in the mid-range then stumbled on the top-end and puffed smoke when we shifted.  The new system allowed us to ride with nearly full power all the way to about 10,000 feet.  The product comes with a complete guide to help tune your machine for any elevation.  To turn the dial all we had to do was remove the seat, making it a much easier chore than actually changing mainjets.  This system will also help when jetting for an aftermarket exhaust system as well, and can work with modified motors.  The Dial-A-Jet does what it says and more.  At $69.95 it beats rejetting every time you change riding locations.  We suggest getting their $10 snorkel kit as well if you ride in dusty or sandy conditions.  Dial-A-Jets can be used on any single or multi cylinder/carb ATV engine.  Call Thunder Products at 320-597-2700 or visit their website at: www.thunderproducts.com.