Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/127253
~ ~.,~!!BENCH
eM
LOCAL EVENTS
Lewis doubles Dual European
Scrambles
Breathing lessons: Air filters
48
otorcycle engines ma y look
rugged and durable from the
outside, butintemally, they are
as delicate as wings on a butterfly.
Just the tiniest amount of dirt, sand
or dust can severely damage or
destroy an expensive engine in a
matter of seconds. However, such
catastrophes can easily be avoided.
Most mechanics will tell you that
your motorcycle's air filter is the key
factor for long engine life and
maintaining its peak performance, It
is for these reasons that air filters
require more attention and maintenance than an y other part on your
motorcycle, more so for off-road
motorcycles than street bikes,
because where there is dirt, there is
almost always dust and sometimes
mud just waiting to be sucked into
your engine. Simply put, an improperly serviced or neglected air filter
can hinder engine performance
and! or lead the way, in the fast
lane, to expensive internal engine
repairs.
An uncared for filter can give a
motorcyclist two kinds of headaches
- the first being the inconvenient
and annoying kind.
If you let an air filter get too
clogged with dirt, it will restrict the
amount of air flow to the carburetor.
When the flow of air is reduced, the
fuel!air mixture, which is fed into
the cylinder through the carburetor,
becomes too rich, resulting in slower
throttle response and a roughrunning engme. Most of the time,
the engme will first be effected at low
rpm, when the throttle is first
applied. The motor will sometimes
sputter and hesitate. This can also
be noticed when the motor is revved
high, which requires more air and
faster air flow. Plus, a too-rich fuel!
air mixture could very easily cause
the spark plug to foul, leaving you
stranded on the trail if you don 't have
a spare plug with you. These kind
of problems will slow you down, if
'not stop you completely, in race
situations.
The second possible headache,
which will most likely result in a
migraine, is the worst of the two. The
aftermath will cost you lots of money
and many hours of down-time.
The more a filter becomes clogged
with grime, the chances of dirt
slipping through the filter and into
the engine is greatly increased. Dirt
particles can plug up the carburetor
jets, or worse yet, make it all the way
into the cylinder and the crank. Dirt
and grit in these places will prematurely wear out carburetor parts or
quickly destroy expensive and hardto-reach engine parts, such as bearings, pistons, rings, cylinder liners,
valves, etc. Get the picture? Dirt and
moving engine parts don't mix. Air
filters are designed to prevent this
from happening.
There are three basic types of filters
used in motorcycles: foam, gauze and
paper. Foam is the most common,
but all of them work on the same
basic principle.
A paper- or gauze-type filter uses
a random weave of paper or cloth
strands. They can only stop dirt
particles larger than the smallest
hole in the paper or strands. Unfortunately, these filters do have flaws.
Every time they stop a piece of dirt,
it plugs up a hole. When the holes
become plugged, it actually filters '
better, but air flow is reduced. When
this happens, a stron~ vacuum is
created and starts to dislodge some
of the dirt particles it trapped earlier
and tends to pull them into the
engine.
Foam filters are more efficient. A
foam filter 'uses a uniform network
of completely interconnected strands
forming a maze that dirty air can 't
avoid, But this alone is only half the
battle.
.
To help catch the grit, the filter
needs to be coated with some kind
of sticky substance, such as oil, either
a specifically designed foam filter oil ,
or everyday 30 wt, motor oil. (But
there are significant differences
between the two oils that we'll
discuss later).
When the filter is coated with a
sticky substance, air contaminated
with dirt is pulled through the entire
volume of the foam element (not just
the surface). During this process, dirt
particles are thrown into contact
with the oil-coated strands as air
passes through the entire depth of
the filter element. The dirt sucks to
the strand; but doesn't necessarily
block the opening. Virtually no dirt
or dust particles escape capture by
the sticky strands and extremely high
air flow and filtering efficiencies are
achieved.
But in severe dust conditions, the
filter can become so clogged that very
little air will pass through.
Although cleaning and servicing
air filters is a relatively simple task,
we all know that it isn't much fun
to do and that's why air filters are,
all too often, unheeded. It 's a dirty
job, but, as they say, someone's got
to do it: Unfortunately, that someone
is you.
How often should you clean your
air filter? Well, that depends. If you
have a street bike then you probably
won't have to worry about cleaning
your filter too often, since dust and
mud isn 't encountered all that much
when riding on pavement. In this
case you can just follow what you r
motorcycle's owner's manual recommends. But if you ride dirt bikes, then
air filter maintenance is priority
number one. Most off-road motorcycle owner's manuals will recommend servicing your air filter after
every ride, usually at the end of the .
day. But that's just a guideline. In
dustier- or muddier-than-usual conditions, you might want to clean
your fil ter each time you get off your
bike. To make the job quicker and
easier on race day, or while trail
riding, you might want to carry an
extra air filter element or two in your
toolbox and just swap filters. It's not
always easy to correctly clean your
air filter while parked in the pi ts or
out in the hills.
In severe dusty conditions, motocross riders might want to clean or
replace the filter in between motos,
while off-roaders might want to do
the same thing in between loops in
enduros or hare and hounds. It can't
hurt to be too careful, because
engines aren't cheap. Generally
speaking, when you finish your ride
and if your goggle lenses and jersey
are covered in dus t, so is your air
filter.
Next week we'll discuss the proper
methods of cleaning paper, gauze
and foam air filters . There is a right
and a wrong way to clean air filters .
Workbench is a weekly column dealing wi,h
mOlorcyclt maintenance, performance and
equipment. Have something that Workbench
can address? Then drop a line Workbench,
Cycle News, P.O . Box 498, Long Beach, CA
'0
90801-0498.
By Donnetta and Bob Murray
Photo by Bob Murray
RED MOUNTAIN, CA. FEB. 25
There was mor e than just on e winner at th e
Huntington Beach M.C. Dual European
Scrambles held a' Teagle Wash near Red
Mountain, but the biggest winner of all was
th e AMAIDistric, 37 Legal Defense. There.
were no trophies for winners or fin isher pins
for th e 780 en tries today : all proceeds from
the entry fees, t-shirt sales and HR780 pin sales
went to th e ca use.
"W e ch anged o ur race to draw attention to
how serious this threat is to us, " said club
member John Karell of 'he bill goin~ before
federallel;;isla'ors that would further limit the
land available to orr-road recreational use.
Karell noted that HBMC hoped their event
would ch allenge other clubs to hold benefit
races for th e fund.
One of 'he most exciting of the 20 races
staged on the four co urses wasthe I 25cc event
on the B course. Leading at the bomb was
Yamaha 's John Braasch with Kawasaki's
Roger Hur and KTM's Jimmy Lewis in hot
pursu it. The trio battled it out through the
canyons. changing positions several times.
Hurd was in the lead when the threesome
made their charge a' a silty uphill. Braasch,
who was in second place, faltered on the hill,
while Lewis made the most of 'he situation
and overtook Braasch. Before the end of the
first loop, Lewis passed Hurd
claim firs,
and had a 30 second lead by the time he passed
through th e home chute, followed by Braasch
and Hurd. Lewis held his position to the
. finish, but was challenged through the second
loop by Braasch and Hurd, who ended the
race second and third, respectively.
The KTM /F&L Fuel/Power Bars/Malcolm
Smith-sponsored Lewis was a double winner
for the day , having won the 125cc race on
th e A co urse, as . well . Lewis led wire-to-wire
followed by Sean Bradley. on a Honda, Hurd,
Ed Pierce and Keith Loonsfoot,
In the first 250cc race of the day on the B
course. Dan Richardson. on a Honda. was
third a t the bomb and quickly passed the two
rid ers in front of him. He was soon way ahead
of th e pack, so far ahead that when he stopped
during th e second loop
replace a breather
tub e that had been spraying him with gas ,
there was no one within sight of him. He
cruised in to claim an easy win. Back in second
place was Randy Moseley , on a Suzuki.
The tabl es were turned on the A course 250cc
even ' . Once Moseley go, through bumping
bars with a co mpe titor through the bomb run,
he rode hard, pacing himself a win. It was
Richardson's 'urn
settle for second.
" I though t I was leading and all of a sudden
someone was in front of me ," said Richardson.
"The second time across the valley , he was
gone."
Finishing third was Brian Nevestich .
R obert Baehr passed Dave Chase on a
downhill in the second loop
snag fourth.
Rounding- out the top fiv e was Frank
Chamberlin,
KTM 's Dan Sm ith cruised to an easy win
in th e Open class on the A course in spite
of still favoring an inj ured shoulder. Kawasaki
Team Green's Ted Hunnicull was having his
own problems, rushing around just before the
race to fix his silencer and men forced to ride
with a loose clutch perch. He still managed
to finish second. ATK's Paul Krause go' a
good start out of the hole, but was passed in
the second loop by Derrick Paiement going
. up into the rocky hills. Paiement nabbed
third, Krause took fourth and Robert Laughlin finished filth,
On the B course, Open rider Paiement led
his class at the bomb with Hunnicutt and
Smith following. Shortly after, Hunnicutt got
by Paiement in 'he rolling hills. Smith snuck
past Paiement in a tight canyon, still in the
first loop, and me three riders maintained
their postiion s to th e finish : Hunnicutt, Sm ith
and Pai em ent. Rounding out the top five were
Laughlin and ATK's Chris Crandall.
It was J ohn Silva, aboard a Kawasaki, and
Honda's Chuck Miller fighting for the win
in both the Vet races . Miller led from the star t
in both contests, with Silva laking Miller haifa-mile ou t in the B course and halfway
through the A co ur se. Wrapping up' the Vet
cla ss on th e A course were Kawasaki's Kenny
Parry in third, Ron Bragdon, piloting a
Honda. in fourth and Kawasaki's Paul Ostbo
in fifth, The B course saw Ostbo fin ish th ird ,
.Bragdon earn fourth and Parry lake fifth.
Kawasaki Team Green's Anna Cody Merritt
o utpac ed a ll ,h e Women in bo,h races for a
double win. Mark Force won th e B Senior .
race by a fu ll ,h ree m inutes, followed by Super
Senior Al Guzman. Clean Loonsfootled most
of the A course Senior race, until he t