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The FMF pipe gave the CR more power on top but robbed low end. A
Pro-level rider would benefit the most with this pipe.
Z
(Below left) FMF supplied us with a 38mm flat-slide Mikuni carbo while
White Bros. (below right) set us up with a White Power shQck.
The front disc and caliper brake
goard from White Bros. is very
sturdy and sano.
'84 CBSOO ,Ronda hop-up
Defense against
the· time bandit
By Kit Palmer
The big-bore class is the smartest class In
motocross to compete in - it costs less to
maintain an Open-classer, and itis not uncommon for the average racer to squeeze out
two or more racing years on a
big-bore and still be competitive on it. Ninetee!1 eighty-four
was the year of the CR500
12
Honda in the Open class; however,
Honda has released a water-cooled
CR500 for '85. Does this mean the
once·mighty air·cooled CR will be a
pushover against its younger brother?
With a small amount of work and
spending a good chunk of cash, we
think not.
Right out of the crate, the '84
CR500 needs some work, mo tly jetting. They come jetted far toO rich on
top and down low - it seems like a
simele problem to solve, but it isn't.
We dropped the pilot jet by one size
and that made a world of difference
down low, but just dropping the
main jet a few sizes doesn't cure the
problem on top. If jetted down enough
on the main jet to get rid of the blurb,
it starts to ping terribly at higher
rpm. Even though big-bore bikes are
intended to be ridden down lower in
the powerband, they need to rev and the'pinging is still a real problem.
The be t we could do with the stock
carb was drop the main jet two sizes
and learn to live with it running
slightly rich on top.
Then we were told that Silkolene
Pro Comp II syntl)etic oil (with an
octane additive built in) wquld "cure"
the pinging problems. We tried it,
but it certainly didn't "cure" the
proble.m. However, pinging was reo
duced slightly.
We contacted the folks at FMF to
see if we could pump out a (ew more
horsepowerfrom theCR's powerplant
and eliminate the pinging problem.
They said their carburetor and pipe
kit would do the trick. We were set up
witb a pre-jetted 3 mm Mikuni (Jatslide carb and a new exhaust pipe.
When we (irst tried installing the
pipe, it didn't fit. After some pipe
The aluminum oval Equalizer
silencer from Answer Products is
worth its $56.95 asking price.
•
modifications with a hammer, we
mounted the pipe and carb and headed
out to the track.
The kit definitely gave the CR
more power on top, but low end
grunt was sacrificed; that's too bad,
because the Honda doesn't have that
mucb low end in the first place. Unfortunately, the engine still pinged,
but not as bad. With the kit, tbe CR
likes to be revved·out and must be
ridden at high rpm all the time - a
pro-level rider would benefit the most.
To make the power a little bit more
likeable, we reinstalled the Slock pipe
and left the flat-slide Mikuni on.
After re-jetting, we were very pleased
with the results: the low end came
back, and the bike ran very crisp and
clean throughout the powerband; using a #45 pilot jet and a #390 main jet.
Not only did the Mikuni make the
CR run better, it also made it start a
little easier. When cold, the CR would
usually fire by the fifth kick; when
warm, the second or third kick.
After all else had failed to eliminate the pinging, we gave the CR to
Harry Klemm of Klemm Research he's widely known as a man who can
cure CR pinging problems. After
some cylinder head work, our CR ran
excellently - the pinging was finally
gone. The last thing we did to the
engine was install a set of Boye en
reeds. What we ended up with was a
very clean-running CR500 that had
quick, crisp throttle response. Low
end became one o( the motor's strong
poi nts, because o( the excellent throttle response. and it ran cleanly
throughout the powerband. When
the stock silencer started showing
sign o( blowing out. we replaced it
with Answer Product'sEqualizeroval
aluminum silencer. Although power
output wasn't af(ected, it did make
the Honda sound very works-ish.
After all the .engine modifications,
we had the chance to pit our '84 air·
cooler against an '85 water-cooled
CR500 Honda through many roll-on
drag races - the results were interesting.
.
Both bikes had fairly worn out
stock Dunlop tires, and the ground
surface was hard-packed and dry.
The first run we made was a second
gear roll-on, and the '84 CR easily
pulled away from the '85 CR. Then
we tried a couple o( tbird gear rollons and the results were tbe same.
What we found out was, when the
throttle was wicked open on both
bikes at the same time, tbe '84 Honda
would hook up much better down
low' and pull hard and smoothly
through the gears, while the watercooler would come on the pipe very
abruptly and the rear tire would
waste its time spinning. With this in
mind, we did a few more second· and
third-gear roll-ons; but this time, the
throttle was wicked open on the '84
and twisted slowly on the '85 - tbe
'85 won easily. It grabbed traction
and started to pull away by a few
bikelengths.
After a few more drags, and a few
laps on the track. we felt our air-cooler
was much easier to ride than the
water-cooler on hard-packed dry sur(aces, but when there is plenty of traction, the '84 has a hard time keeping
up with the '85.
Box stock, the '84 CR500 suspension
is, at best, okay. So, we let White
Bros. perform their suspension magic.
In the rear, they installed a White.
Power shock with a remote reservoir
that has seven compression and II rebound external settings. Then it was
set up internally according to the rider's weight and riding classification.
