“The VentStop puts an end to the problems caused
by the fuel tank vent hose that every machine
suffers from; Fuel oxidation, water in fuel,
hydrocarbon vapor pollution, hard starts, fuel
varnish and gum, engine knock, and contamination.”
– Whiplash Systems.
In all fairness when we first heard of this product
and how it supposedly works we were skeptical.
The vent hose on your ATV gas cap is designed to
allow air into the fuel tank as the fuel level decreases
while the engine is running. Without this
hose or airflow, your engine would starve from the
lack of fuel. Ever try pouring gas out of
a gas can without opening the vent cap? The
same problem would occur with your gas tank if it
didn’t have the vent hose or air flow.
actually receiving several evaluation units, we
thought, “How could something so simple say it can
help so much?” The second question was, “How in
the world are we going to test the units and get
solid evidence that the VentStops work?” Scratching
our heads and pondering several testing scenarios,
we decided to put our VentStop units through the
riggers of a thorough test. This is one of
those products that cannot be evaluated in a short-term
test. So we sat out to do a long-term evaluation.
We tested our units on three quads: A 96 Yamaha
Warrior, a 93 Warrior, and the final quad being
a 97 Kawasaki 4X4 Prairie. All three quads
have been religiously maintained. Multiple
oil changes per year, airbox lid problems corrected
with a Proflow adaptor (Warriors only), carburetors
have been annually cleaned, high quality gas has
been used in each tank fill up, etc. You get
Of these quads, the Warriors are the hardest
to start in all conditions. Not overly surprising
due to their engine’s age and years of heavy to
hard use. No internal modifications have been made
to these engines. They are bone stock.
The VentStop is made of a high quality metal
and its polished metal look will blend nicely with
any chrome handlebars. At the time of writing
this article, the product is holding up well and
signs of wear. Installation of the VentStop
was a snap. You can install the VentStop on
your right handle bar brake reservoir or brake lever
perch (bottom bolt) or anywhere you have a similar
sized bolt. We choose the recommended location
on the Warriors, but we had to place the VentStop
on the upper bolt for the Prairie, as the throttle
cable would interfere with an installation on the
bottom. Wherever you install the VentStop,
be sure you save the bolt that you take out.
We recommend you put the bolt in a ziplock bag or
sandwich bag labeled appropriately for safekeeping.
Use of the product is pretty simple. When
you are done riding and you turn off your quad,
take the end of your vent hose and plug it into
the VentStop. When it’s time to start your
quad, simply unplug your vent hose, and place it
back in its normal location. That’s it!
An initial problem we encountered was that the Prairie’s
vent hose appeared to be too large (diameter wise)
for the VentStop. With a little pushing and
squeezing the end of the hose, we were able to finally
put the vent hose into the VentStop. After
several more installations and removals, the vent
hose became easier to push into the VentStop.
a 4 month plus evaluation period the Warriors were
ridden the way they were designed: Sport/Recreational
Riding. We raced around heavily wooded trails,
moderate to steep hill climbs, creek crossings (Lots
of water), sand bars, mud running, occasional MX
track riding, run WOT down gravel roads and old
abandon railroad beds for miles, and crawled up
and down steep rocky tree rutted hills at a snails
The Prairie was used as it was designed:
Utility work. Our Prairie is used to mow over
8 acres of grass per week. Average mowing
time is around 6 to 7 hrs per mow. The mowing
was completed with an average weather temperature
of 85+ degrees. Some occasions the temps were
well in the upper 90’s. On several occasions
we used the Prairie to pull a wagon full of firewood
from the woods. The Prairie was also utilized
to transport its owner and his fishing equipment
to his favorite fishing hole. This required
crossing a creek several times to reach the “Honey
Hole.” The final test was a mud run with the
Prairie. The Prairie with its 4X4 traction
and powerful engine was needed several times to
extract other quads from the muskeg (Mud).
The different types of riding, uses, and conditions
were just the type of riding needed to fully test
Our first test was to see if Whiplash’s claim
of condensation really does occur within the tank.
“Water in Fuel
When humid air is drawn into your fuel tank,
the water vapor condenses on the inner walls
of the fuel tank, like the bathroom mirror after
you shower. This condensed water, now in droplet
form, runs down into the fuel due to gravity.
The result is hard starting, miss firing, engine
damage, and poor performance.”
As the Prairie was used to mow grass, it would routinely
see slow paced work with higher than normal engine
The external radiator fan would consistently
run after an hour or two of mowing.
We never had the hot water temp light come
on, but from the heat being generated from the engine
you could definitely tell the engine was producing
While mowing we would take necessary breaks
to refuel and allow the engines (quad and mower)
to cool down.
This is where Whiplash claims the condensation
Here is how we decided to test this claim:
We did not use the VentStop during the first
weeks of testing on the Prairie.
We allowed the vent hose to sit where it
normally would and continued to perform its designed
We took the vent hose off of the quad after several
lengthy cool downs and blew a shot of air through
the hose while it was directed toward a piece of
If there was water in it, the air would surely
blow it out and onto the paper.
No moisture or any type of liquid was found.
We thought for sure if Whiplash’s claims
were true, we would find condensation.
Ok, time to use some of that 8th grade
science knowledge we stored away for just this purpose.
Lets make our own test.
We took a glass jar, put a make shift stopper
with a hole in it at the top, heated the jar with
a blaze jelled methanol chafing dish fuel (Camping
fire fuel for outdoor cooking).
We let the jar heat up till it was hot to
touch and then allowed it to cool.
As it cooled we found that condensation formed
on the inside of the jar.
Ta-Da, Whiplash’s claim is true.
Logic tell us that a quad’s fuel tank is
essentially the same type of setup as our jar test,
so yes, condensation can occur within the gas tank
during cooling down periods.
Ever wonder why your Dad always told you
to put the gas cap back on the gas can after you
poured gas from it?
Now you know why.
Our second test was to see if Whiplash’s claim of
Solid Particle Fuel Contamination occurs.
“Solid Particle Fuel Contamination
As the temperature of your fuel decreases, air
from the surrounding environment is drawn into
the fuel tank through the vent hose. This air
contains thousands of unique, destructive particles.
This includes; Dust, water (humidity), and debris
from highway transport. The result is damaged
We decided that the best way to test this was
to ride our quads without using the VentStop during
cool downs. We would then take the vent hose
off after our cool down periods, use a regular Q-Tip
to insert into the ends of the hose and see if we
could get some dirt or dust particles on the Q-Tip.
Success!! Wait, that’s bad. This means
our gas is being contaminated on a regular basis.
Boy, are we glad we have installed fuel filters
to catch those particles. Again we ask, “Ever
wonder why your Dad always told you to put the gas
cap back on the gas can after you poured gas from
it? ” To keep dirt, dust, and moister out
of the gas can. Hmm…Whiplash is really onto
something with this VentStop.
problem we encountered was after dusty or muddy
riding, our VentStops would collect dirt and mud.
If we were to plug are vent hose into the VentStops
it was obvious we could eliminate the benefits of
the VentStop as contaminates could get into the
end of the hose and pulled into the gas tank during
normal operation. We found a solution to this
problem with a rubber cap devise we found at our
local hardware store. This rubber piece easily
fit over the VentStop and kept it clean. Our
other problem was where would we keep the rubber
cap when the vent hose was plug in? We quickly
found that the throttle stop screw, if your quad
has one, works great.
After our first two weeks of use, our Warriors
still started hard. The Prairie, never having any
difficulty starting, had little notice of improvement.
We started to doubt the claims that this would be
the cure for the hard starting problems. But, we
contributed these hard starts to the all ready contaminated
gas and contaminates still residing inside the tank.
We found that once you consistently used the
VentStop, our hard starts started to subside.
A few more tanks full of clean gas and our test
quads ran better and started much easier than before.
Was it the VentStop doing its job or was it just
better gas from each fill up? We made sure
that the same gas can was used to fill each quad
and that the same type of gas was used during each
Over the next several months, our VentStops were
producing results. We rode during numerous
hot humid days. Coupled with several very cool overnights.
Our temperatures would fluctuate from 90 degrees
plus and then the cool overnights would plump-it
down to the middle to upper fifties. This
huge difference in air temperatures gave our VentStops
the ultimate test to see whether they would keep
out those harmful enemies that attack your gas and
turn it into power robbing droplets. We noticed
a big difference in the ease of starting our quads.
We even noticed a slight increase in throttle response.
Again, was it the VentStop doing its job or just
Water and Gasoline Doesn't Mix.
Water in gasoline is a serious problem. It causes
carburetor corrosion along with a host of other
ill effects. Moreover, the engine won't even
run if there is too much water in the fuel system.
Can you ruin a perfectly good motor by using poor
fuel? You bet, and it happens all the time. It can
be an extremely painful lesson with the current
cost of engine rebuilds. Worst of all, the
process may not take very long -- sometimes less
than one riding season.
While there are some additives on the market
that use alcohol to absorb a small amount of water,
the only sure way to get water out of a tank is
to empty your tank and fill it with good gas or
you can extract the water out. Water, being heavier
than oil or gasoline, will always go to the bottom
of the tank. Empty out an amount of liquid (water
& gas) through the fuel hose and then allow clean
gas through the fuel lines until they are completely
flushed. We also recommend that you empty
and flush the float bowl as well. Unfortunately,
you cannot always keep all of the water out of your
gas. Once there's enough water in the gas, your
best bet is to completely empty the gas tank and
refill with fresh gas.
The best way to avoid water problems is to keep
it out of the fuel in the first place. Always keeping
the tank full to eliminate moisture condensation
is a good start. But, who can always keep their
quad’s fuel tank completely full? Not us.
Dirt/Dust Particles and Gasoline Doesn’t Mix.
Dirty gas and your quad’s engine is a quick recipe
for a grenading engine or at the very least a shorter
engine life. Dirty gas can cause a loss of
power and compression due to piston expansion and/or
metal fragments contaminating the interior of the
cylinder. Seizures can be total (piston will not
move) or partial (piston moves but has scored the
cylinder wall). Keeping dirt and grime out
of your gas is important. We highly recommend
you install an inline fuel filter to help stop these
destructive particles from reaching your engine.
We were unable to test the claim of fuel oxidation/varnish
and gum formation as describe by Whiplash.
“Fuel Oxidation/Varnish and Gum Formation
As your fuel is mixed with oxygen from the surrounding
air, oxidation occurs. The by-product of fuel
oxidation is the production of large molecules,
also known as Varnish and Gum. The result is
a dirty carburetor and a stiff fuel shut-off
We never let the gas sit long enough to test
this. We do recommend that you use a fuel
additive or stabilizer if your quad or your gas
in a gas can does sit for a long period of time.
These additives or stabilizers will stabilize your
fuel keeping it from forming the varnish and gum
contaminants. Some additives also reduces
cylinder-head combustion temperatures as well as
inhibits both carbon buildup and corrosion. They
can also help to keep the fuel system clean, while
reducing harmful emissions.
During our 4 month plus evaluation period we
found the VentStop won’t be the miracle cure the
first time you use it. If you use it as advertised
and use it on a regular basis, you will notice results
and you will keep the gas within your quad's tank
clean from contaminants. Cleaner gas will
give you higher performance and longer engine life.
The VentStop is only $19.95. You can
easily spend ten times that on engine repairs.
Combine the VentStop with an inline fuel filter
and treat your gas from the gas can the same, by
keeping it free from dirt and water, your quad will
run better and cleaner.
7287 Penny Hill RD
Eden Prairie, MN 55346
Phone: (763) -691-1673