1968 Yamaha Yvon Duhamel Daytona Racing - Vintage Motorcycle Ad

Description

1968 Yamaha Yvon Duhamel Daytona Racing - Vintage Motorcycle Ad
Original, vintage magazine advertisement.
Page Size: Approx. 8" x 11" (21 cm x 28 cm)
Condition: Good
How Yamaha’s
5-Port Power
helped me win
at Daytona
by
YVON DUHAMEL
Winner of the 1968 Daytona 250cc Event
and Number 2 in the "big bike" 200 Mile
Classic.
“When I decided to race at Daytona, there were
two things I wanted out of my bike. The most
performance I could get out of a given amount
of ccs. And an engine that wouldn’t quit no
matter how hard I hammered it.
“After riding Yamahas, and looking at their
Daytona wins for the past four years, I felt that
this was the one bike that had the guts to do it.
“The reason, of course, was
the fact that Yamaha is the first
and only bike manufacturer who
makes a 5-port engine. Those
two extra ports on each cylinder
deliver a cleaner charge for each
stroke, and when you’re riding in
competition, a performance ad-
vantage like that can make the
difference. That’s probably why
Art Baumann and I were able to
do so well against those big
750cc jobs with our 350cc
Yamahas.”
The reason for 5-Port Power
With an ordinary 2-stroke engine, when both the ex-
haust and transfer ports are open, some of each fresh
induction mixture is lost directly out the exhaust port.
And the burnt residual gases cannot be scavenged
from the combustion chamber, thereby prohibiting the
fresh charge of fuel from completely filling the combus-
tion chamber.
Yamaha's 5-Port System eliminates combustion prob-
lems. Two additional ports on the back
side of the cylinder swirl the fresh
charge straight upward toward the top
so that burnt gases are swept out
and the fresh air-gasoline mixture can
fill the top part of the chamber. Con-
sequently, all residual gases are scav-
enged from the combustion chamber
and the fresh induction mixture is
spread throughout the entire cylinder
area.
Result: Broader power range ■ Quicker
throttle response ■ Better top end ■
Better fuel economy ■ Cylinders,
heads and plugs stay cooler.
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