Motorcycle question...

"OpposResidentLexusGuy - USE20, XF20, XU30 and Press Cars" (jakeauern) 10/31/2016 at 17:41 • Filed to: None

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Was walking the doggo when I saw and heard a Yamaha R1 at the stoplight. As it sat there it ran almost like a high horsepower muscle car with a galloping sound. Why would this be?

bob and john > OpposResidentLexusGuy - USE20, XF20, XU30 and Press Cars 10/31/2016 at 17:46

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09+R1s dont have a tradition 4 cylinder crankshaft. they have a cross plane crank.

quite interesting actually.

Tripper > OpposResidentLexusGuy - USE20, XF20, XU30 and Press Cars 10/31/2016 at 17:47

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I believe that the R1 uses a cross-plane crankshaft (at least the newer ones do). A friend had a 2015 up until a few months ago. You couldn’t really hear it stock, but after he added an exhaust it sounded as you describe. 

OpposResidentLexusGuy - USE20, XF20, XU30 and Press Cars > bob and john 10/31/2016 at 17:48

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So could it just have been what all R1s sound like with the cross plane?

bob and john > OpposResidentLexusGuy - USE20, XF20, XU30 and Press Cars 10/31/2016 at 17:50

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that is what all 2009+ r1s sound like.

OpposResidentLexusGuy - USE20, XF20, XU30 and Press Cars > bob and john 10/31/2016 at 18:24

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That’s the sound exactly! Those bikes sound like they do not want to be doing anything but going fast.

jimz > OpposResidentLexusGuy - USE20, XF20, XU30 and Press Cars 10/31/2016 at 18:58

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what they said. the ‘09+ R1's engine is basically half of a crossplane V8, the most common V8 layout in street cars. the four crankpins are spaced around the centerline in 90 degree angles, so viewed on end the crankpins would form a “cross” or T shape. But, since the engine is a four stroke, this means the firing interval is an irregular 90-180-270-180 degree pattern. this is what gives V8s that “burble” at idle and that “roar” when they’re running full-out.

here’s a crossplane V8 animation:

like Peter Black’s video says, most 4-cylinders have a flat plane crank, with an even 180-180-180-180 firing interval. Plus, if you take two four cylinder designs with this crankshaft, widen the rod journals to fit two rods, and arrange the cylinder banks in a vee, you have a screaming flat-plane V8.

here’s a flat-plane V8 animation:

yamahog > OpposResidentLexusGuy - USE20, XF20, XU30 and Press Cars 10/31/2016 at 19:10

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Those bikes sound like they do not want to be doing anything but going fast.

Yep!

Joel Ness > OpposResidentLexusGuy - USE20, XF20, XU30 and Press Cars 11/01/2016 at 07:41

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That is a very succinct way of describing super sport bikes. Anytime you ride a bike like that and use less than 7/10 of its potential it feels like it’s groaning to be let out of its cage.