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The Springfield Mile here in Central Illinois is one of the
most famous one-mile dirt racetracks in the country. I'm sure
it was built for horses but motor racing made it famous. When
we moved here last summer I looked forward to seeing both four-
and two-wheel racers go at it on the dirt.
Due to some biker bash problems years ago the motorcycle races
aren't promoted locally so I missed them last summer. I did go
to the USAC Silver Crown race and had a great time. I was disappointed
to learn the motorcycle race this year ran the same day as the
Indy 500 which I couldn't miss. Reading the newspaper on Monday
morning, however, I found out rain had caused the bike race to
be postponed a day so I could go after all.
I left the house about 7:30 am and was at the Illinois State
Fairgrounds 10 minutes later. It was overcast and cool enough
to need an overshirt, but would be sunny later. Several hundred
people were already on hand and expensive motorcycles were everywhere.
I found the office and a nice lady gave me a media pass and
a race program. After a short walk through a tunnel under the
main straight connecting the grandstands and the infield, I found
myself in a paddock full of pickup trucks, small trailers, motorhomes,
racing motorcycles, and guys in leather suits.
One of the guys was a girl!
Michelle DiSalvo from Waterford, Calif. rode in the H-D Sportster
class, a support series to the Grand National Championship.
Chris Carr, the reigning national AMA champion, poses on his
motorcycle during a taping for TV.
Chris, a former TVM subscriber, remembered me from when we
both lived in Northern California. He introduced me to his crew
chief and team manager, Kenny Tolbert, who was kind enough to
answer my usual array of questions. That's Kenny with Chris sitting
on the rear bumper of their truck.
Kenny was kind enough to answer my usual array of questions.
I started by asking about the engine which Kenny builds himself,
"Some tracks you have to go slow to go fast, if you know
what I mean," Kenny said, looking toward the V-twin Harley-Davidson
racing bike sitting on a jack stand right next to us. "Chris
is an aggressive rider and I have to detune the engine so he
can get some bite. I do that with ignition timing and carburetor
tuning. The engine has dual-plug heads. The carbs are Mikuni
with slide throttles. We use race gas and have to meet noise
limits at all the tracks.
"The chassis we use hasn't changed much in the last 20
years. The brake is on the rear only. We use KYB front forks
that are stock on the Yamaha R-6. The shocks in the forks are
"At the rear we have remote-reservoir, double-adjustable
Penske shocks. This bike has shocks with a digressive piston.
The spare bike is setup with shocks using a high-flow piston.
Different drivers like different shock setups. [Just like four-wheel
drivers.]We also use the preload on the springs as a tuning adjustment."
I can see the shock is tucked up in front of the rear wheel
below the rider's seat. There's a linkage mechanism but engine
intake filters and exhaust headers keep me from locating all
the pivot points. Kenny tells me the motion ratio is 2/1, wheel/shock.
"Several companies supply tires: Goodyear, Dunlop, Continental,"
Kenny says. "There are two different compounds per brand.
We'll use the hardest compound here to keep from blistering tires.
The sun will come out later and this track will get a coat of
rubber just like pavement. For the race we'll probably have to
cut some heat sipes into the tire tread."
I asked Kenny about geometry adjustments. "The head angle
is fixed because the head tube is welded to the frame, but an
eccentric bushing lets me change the fork offset to adjust the
How do you determine what adjustments to make? "Chris
tells me. He's riding the thing."
Any titanium parts? "The pivot bolt where the rear suspension
arms attach is titanium and so are the exhaust megaphones. And
some engine stuff. But not much. We're not allowed to use titanium
for axles. They have to be magnetic material [steel]."
How important is the preparation of the track surface? "They're
out there with trucks running it in for us now. That's good.
There'll be less mud and spray later."
Rich King was the only rider to have FOUR bikes at his disposal.
He's the Harley-Davidson factory rider. Just right of center
sits Bill Werner, the most famous bike tuner in the U.S. He works
exclusively for H-D.