Kawasaki patents 90° cylinder engine

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kawasaki_90_degree_cylinder.jpgKawasaki is still developing the horizontal-cylinder engine, this time filing patents for a 90° cylinder as opposed to the 60° cylinder that we wrote about last year. This revision adds a stacked gearbox, which adds increased swingarm length to the long list of benefits such an arrangement would bring.
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Performance advantages of this engine layout include reduced weight and
reduced size thanks to combining the block with the transmission
housing, increased stability thanks to the gyroscopic effect of the
crankshaft being moved closer to that CG and increased perceived
smoothness because of the change in prevailing vibration angle. There’s
also advantages to the intake system thanks to a simplified route for
pressurized air. The decreased overall height of the engine allows a
so-equipped bike to be radically repackaged, the center of gravity
could either be lowered or raised depending on which handling
characteristics were appropriate for the machine in question.

The horizontal-cylinder engine is already used in bikes like the
Husaberg FS 570 Supermoto, where it reduces the tendency for the
motorcycle to upright itself under power and increases the ground
clearance in addition to allowing for a straighter path between airbox
and cylinder. This setup differs from the reversed-cylinder engine of
the 2010 Yamaha YZ450F in that the exhaust and inlet ports are still
conventionally located on the front and rear of the engine.

In the past, Kawasaki has patented the horizontal-cylinder engine for
use in a variety of machines — ranging from quads, to dirt bikes to
supersports — meaning it could be looking to employ such an arrangement
across its model range, lending its products a clear mechanical
differentiation from their too-similar Japanese competition.

Image via MCN

  • Isaac

    Can’t wait to see the nex Ninja ‘ZX’.

  • Justyn

    Another advantage is because Kawi likes using super narrow frames, now the entire top of the motor is accessible from the front of the bike.

  • http://www.fetherston.tumblr.com fetherston

    Looks like a wonderful platform for forced induction!

  • http://motarded.blogspot.com Troy Smith

    Excuse my ignorance but how can they patent it if Husaberg has already built it?

    • http://hellforleathermagazine.com Wes Siler

      They’re aren’t patenting slant-cylinder engines in principal, rather technology specifically relating to this application.

  • area_educator

    So, Kawasaki woke up one day and noticed the BMW K-series (old and new)?

    I do recognize that they’ve added the twist of putting the transmission under the crankshaft, instead of behind.

    • http://hellforleathermagazine.com Wes Siler

      The K-Series just tilts the whole thing forward, this actually alters the angle at which the cylinder mounts to the block.

      • area_educator

        The original K-series laid the cylinders completely flat, above the oil-pan. The current K series (Damn BMW’s abandonment of logical naming schemes)looks an awful lot like this, except the transmission is behind the crank, not under it.

        There’s a lot to be said for this setup, I’m sure. I can envision several benefits to tucking the cylinder up and back, above the transmission. But it does seem like they looked at the K-series and said “That’s a really good idea. Here’s a way we can make it a little better.”

  • joneez

    Hopefully they’ll make this in a MotoGP “big bang” version for the ZX!