Da}{tona.
, Laconia.
osport.
flASH: Ron Pierce swept to victory In the 50 Mile Amateur Road Race at Indianapolis
on August 4th aboard a 350 cc YAMA HA, defeating 500cc and 150cc machines on the fast horsepower course.
Keith Mashburn contllfiled his winning ways with a double headed victory at Ascot Par1< winning
the Flattrack Novice Main Event on Friday, August 2nd and the TT Novice Main Event on Saturday
August 3rd.
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When we first announced 5-port
power, we got mixed reactions:
"Hmm
really . .. good
for you
yawn."
:
Since then , we've visited
a few race tracks.
:'"
"' 1
(Daytona : 7 out of the f irst
10 places in the 250cc·Race.
2nd and 3rd in the 200 Mile
Classic against machines twice
our size. Laconia: 8 out of the
first 10 places in the 75·m ile
Expert. 250cc Final. Mosport :
1st in both the 250cc and the
Open class.)
Suddenly, everybody's interested.
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Here's the difference with 5·port power:
In an ordinary 2-stroke engine. burnt gases
at the top of the combustion chamber keep
the fresh charge of fuel from completely filling
the chamber. Some of the fuel goes straight
out the exhaust port.
s-port power puts two extra ports at the back of
the cylinder. Fresh fuel swirls up into the top of the
chamber (not out the exhaust) . All the burnt gases are
pushed out . The chamber is completely filled with fresh fuel.
YAMAHA~
INTERNATIONAL CORPORATIO N · S I N C E 18S7
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