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I have no idea where you found that, but that is awesome for any tech heads. Complete description of YICS, as well as the description of why the DOHC YICS is different (and doesn't need the special 4-cylinder tool for balancing carbs.)
To quote page 102:
OPERATION
This new DOHC twin-cylinder engine is only 40mm wider than the OHC single-cylinder engine on the
SR500. The generator is positioned on the back of the cylinder assembly above the crankcase. A large
diameter clutch is adopted, but the clutch housing is thinner than before. The adoption of an electric starter
has eliminated the need for a kick crank. All of these factors have contributed in making a slimmer power
unit.
The YICS adopted on the XS series is different from that on the 4-cylinder XJ series in that it features a
separate chamber on each side so that air/fuel mixture is compressed into the chamber by utilizing the
induction momentum during compression stroke. The passage leading to the chamber is smaller in diameter,
and the compressed air/fuel mixture is made into a jet stream by utilizing the negative pressure during
induction stroke. The jet stream is led into along the inner wall of the cylinder, thus producing a strong swirl.
This system is based on that of the XZ400 but differs in
that each chamber is positioned on the inside of the cylinder
block.
RESULTS
The air/fuel mixture fills the cylinder quickly, which
in turn shortens the period of combustion time, thus,
increasing power output and reducing fuel consumption.
To quote page 102:
OPERATION
This new DOHC twin-cylinder engine is only 40mm wider than the OHC single-cylinder engine on the
SR500. The generator is positioned on the back of the cylinder assembly above the crankcase. A large
diameter clutch is adopted, but the clutch housing is thinner than before. The adoption of an electric starter
has eliminated the need for a kick crank. All of these factors have contributed in making a slimmer power
unit.
The YICS adopted on the XS series is different from that on the 4-cylinder XJ series in that it features a
separate chamber on each side so that air/fuel mixture is compressed into the chamber by utilizing the
induction momentum during compression stroke. The passage leading to the chamber is smaller in diameter,
and the compressed air/fuel mixture is made into a jet stream by utilizing the negative pressure during
induction stroke. The jet stream is led into along the inner wall of the cylinder, thus producing a strong swirl.
This system is based on that of the XZ400 but differs in
that each chamber is positioned on the inside of the cylinder
block.
RESULTS
The air/fuel mixture fills the cylinder quickly, which
in turn shortens the period of combustion time, thus,
increasing power output and reducing fuel consumption.
Specdog
XS400 Addict
Great read, thanks for posting that. I was interested in the Omni-Phase balancer. What a piece of crap that was.
That is some valuable info. Now I finally understand the YICS system and how it was implemented on the DOHC 400's.
Thanks Drewpy!
Thanks Drewpy!
