Get Rich Quick
There are a lot of incorrectly jetted ATVs motoring around. We
know, because we've ridden some of them. You know the type-hard
starting, dead spots in the throttle response, weak top-end power or
blubbering. It may sound strange, but quads with modifications are
some of the worst running machines we've seen. That's because
jetting often needs to be richened for the improved breathing of
modifications like high performance air filters and exhausts.
DUMB AND LAZY?
Most riders know very little about jetting carburetors. Some
just don't want to struggle with carburetor adjustments. We don't
blame them. ATV carbs are usually nestled into cramped areas and
dealing with their tiny screws, clips and jets can test the patience
of professional mechanics. Jetting a carburetor properly means
getting the air-to-fuel ratio spot-on for your machine at low
midrange, and wide-open throttle. That means you've got to adjust
three systems within the carburetor that handle these speed ranges.
Even when you get it right, a big change in temperature or elevation
may call for more adjustments.
The Dial-A-Jet is a product claimed to relieve much of the pain of
jetting. Using a siphon fuel feed from the carburetor through a
precise valve that feeds atomized air and fuel through a nozzle near
the mouth of the carb, it allows external air-fuel mixture
adjustment. Before you drop kick all the jets you have toward the
nearest dumpster, you should know that the makers of Dial-A-Jet
recommend reducing your machine's main jet two sizes if you wish to
take advantage of the full range of adjustment it can provide. Our
test subject, a Honda 400EX, was already too lean because someone
had removed that airbox lid, so we opted to add the device without
changing the main jet to see if the Dial-A-Jet alone could correct
the lean condition.
NOT AFRAID OF NEEDLES
Installing the Dial-A-Jet was simple. A fitting replaces the drain
screw at the bottom of the carb. After you make a hole in the
intake boot, you insert the Dial-A-Jet nozzle. The valve/nozzle
assembly attaches to a zip-tie, which holds it in place on the air
boot. You then run a small hose from the fitting on the carb to the
Dial-A-Jet valve. Since the Dial-A-Jet draws in air as well as
fuel, a filtered snorkel kit for the device is required for ATVs.
It's an extra-cost item, but it keeps dirt out of the Dial-A-Jet and
Even without turning the adjuster on the Dial-A-Jet, our initial
test runs revealed that the Honda was running a bit better. That
makes some sense; it was getting more fuel. It still didn't have
the solid, even pull of a well-tuned stocker with it's airbox lid in
place, so we cranked the adjuster to position five, full rich. It
ran too rich, so we clicked to number four. Still not right, but
better than the stumbling lean response we had before we installed
the Dial-A-Jet. We settled on position two and found ourselves with
a crisp running 400EX. The Dial-A-Jet is the easiest was to adjust
jetting that we've tried. It can't replace re-jetting entirely, but
it's great for fine tuning. It certainly beats the tedious, trial
and error open-carburetor surgery we're used to.
Rating:*****. Price: $74.95. Snorkel Kit $10.