Tire Selection - Honda CR250R 2004 Owner's Manual

8. GEARING SELECTION
CAUTION:
•
Unless you have the required mechanical know-
how, tools, and an authorized Honda Service
Manual, sprocket changing should be done by your
authorized Honda dealer.
Some outdoor tracks may be watered heavily prior to
the first race, then lightly or not at all during the day.
This results in a track that is slippery during the first few
races, changes from good to great then back to good
traction for part of the day, then may end the day with
a slick, rock-hard consistency. Ideally, your gearing
should be adjusted to suit all these conditions.
•
Wet and slippery or sandy conditions: use less teeth
than the standard sprocket to keep the engine rpm
down, and avoid unwanted wheelspin. The engine
may bog in certain corners so you'll need to slip the
clutch to compensate; downshifting may be too
drastic a change in speed.
•
Average conditions: use the standard sprocket.
•
Hard (but not slippery) track conditions: use more
teeth than the standard sprocket to keep the engine
rpm high where the engine produces the most
power. This may require an extra upshift on certain
sections or perhaps you can just rev it out a bit
longer.
Another example of the benefits of proper gearing
for soil conditions is experienced when riding on a
sand track. Of course, you want to keep the front
end light so the front wheel virtually floats from the
peak of one whoop to another. Generally speaking,
with higher than stock overall gearing it is easier to
maintain that perfect attitude of maximum rear
wheel traction and a light front end because you re-
main in the powerband longer in each gear.
If you've ever run too low overall gearing in the
sand, you've noticed that you are tapped-out very
quickly and the front end feels very heavy. You
don't want to be steering the bike with the front
wheel much in soft sand. The taller gearing allows
you to steer more efficiently with throttle control
and body English.
Sometimes alternate gearing can help even if track
conditions are consistent throughout the day. If
there are sections of the track on which you must
consistently over-rev the engine (rather than losing
time by upshifting), perhaps "taller" gearing (a
smaller driven sprocket) will help.
Whenever you change gearing, have someone check
your lap times (before and after) to get an honest
appraisal of the changes. Use a stopwatch for consist-
ency. "Seat-of-the-pants" feelings can't be trusted
since eliminating wheelspin can make you feel like
you're going slower, but in reality you've decreased
your lap time by increasing your speed a little bit in
each section of the track.
But everything is a compromise, so sometimes you'll
have to sacrifice performance on one section of the
track to gain a better overall time. You should shoot for
the lowest lap times and not worry about some sections
where the gearing feels wrong. Of course these recom-
mendations must be tempered against your ability, the
actual layout of the track (long, short, hilly, etc.), and
your riding style. But generally, these recommendations
will suit most conditions and most riders.
Whether or not it's worth the effort and time it takes to
swap to gearing that might help you pick off a position
or two at the finish of your next moto is up to you.

9. TIRE SELECTION

Choosing the correct tire tread pattern and rubber com-
pound can make the difference between finishing first
or somewhere in the pack. The tires your CR comes
equipped with are a perfect "happy medium" for the
variety of soil conditions the majority of riders are likely
to encounter.
Motocross tire design has developed into an extremely
intense area of study. The descriptions given here offer
CR riders a very basic knowledge of the factors involv-
ed in tire design so the proper tires can be utilized and
the best possible competition result achieved. More tire
information is available in the Maintenance section,
page 10. The most complete information should be ob-
tained from the various tire manufacturer represen-
tatives and dealers.
•
Hard, Slick Terrain requires tires with many relative-
ly short knobs that are close together in order to ob-
tain the largest possible contact patch on the sur-
face. The rubber compound needs to be softer for
hard ground in order to hook up, but not so soft that
the knobs easily roll over and keep you from holding
your line. These tires tend to wear more quickly
than some because of the combination of soft rub-
ber and hard terrain.
•
Very Tacky Soil or Muddy Courses require a more
open tread pattern to avoid clogging. The rubber
compound for these conditions can be harder to pre-
vent the relatively long knobs from bending back
under acceleration or wearing quickly.
•
Loose and Sandy Soil conditions are best handled
with a tire that is similar in construction to those
needed for tacky soil and mud, but with a few more
knobs.
Don't stray from the factory recommended sizes since
this may affect handling and even acceleration.
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