I do not follow too heavily the sport bike scene, but I do find the engineering behind engine design to be highly interesting. This guy has produced some great videos about crank design. Here is one about the Yamaha cross-plane I4 used in the R1. Perhaps the only cross-plane four cylinder. If you are not into sport bike racing, you may still find his engine videos informational.



https://www.youtube.com/watch?v=uM-ycHS9uvw

Very cool video, and a good explanation of cross plane design.

Wow that was a good video. He touched on pretty much everything in incredible detail! I like that he brought up the sound difference and explained that too. I learned quite a lot today.

Given the benefits of the cross plane and how they are not really going to be seen on the street for the vast majority of riders out there it makes sense that other manufacturers like BMW, Kawasaki & Suzuki have kept their howling flat plane crank engines. I’d always kind of wondered why other manufacturers didn’t follow Yamaha. Given the advantages and disadvantages both engines have it makes sense.

Personally I prefer the screaming sound of a flat plane crank over the cross plane but this is totally subjective. I’m not going into turns hot enough that I need to worry about the pulses of the engine on the tire at the absolute limits of grip. Track day junkies however do care a lot more about such things. That is a superb video. It really covers everything.

Thanks for posting this!

Fascinating.

Thanks for posting!

Good video thanks for posting

quote:

Perhaps the only cross-plane four cylinder

Actually you can also get the cross plane four cylinder in the naked Yamaha MT-10 also. The MT 10 does not have the raw power of the R1. But my 2018 MT 10 is a much more comfortable street bike with stronger midrange than my 2016 R1 I sold when I got the MT-10. When you ride Yamaha cross plane four cylinders they have a very intoxicating sound to them.

Masao Furusawa invented it for Yamaha in 2004 for Valentino Rossi and their M1.

It made production first in the R1 in 2009. I bought it the first year because the crossplane inline 4 in my R1 has the same firing order as a 90 degree V4. Honda’s unwillingness to make a 1000cc V4 sportbike for almost a decade when the customers demanded it….had me jumping at the chance.

The crossplane, like the 90 degree V4 it mimics, puts a constant pulse on the rear tire. Gives you better grip out of the corner, better feel, and better sound. And it doesn’t suffer from intertia torque at high RPM.

In the intro they asked why for the R1 and not the R6? I answered to myself, for the tire pulses and the R6 isn't powerful enough to need it. This was why Harleys dominated flat track for decades.

Sigcrazy7, thank you for posting this video.

You're right that Yamaha chose this for Valentino Rossi to give him better traction. The real reason they chose this crank is because it was cheaper to swap cranks than to design a V4, and redesign the chassis.

Before the M1, the 500cc two stroke GP bikes used "Big Bang" cranks. They are essentially the same concept and would fire all four cylinders in a short interval. Uneven firing orders help the rear tire achieve better traction.

An inline 4 on a dirt track would suffer from traction. A V4, or even better a V2, would have more traction on dirt than a traditional inline four cylinder engine.

They also came to understand or probably already knew that an in-line four is much more agile and can carry more corner speed than a V4. If an inline 4 can get out front it stands a great chance of running away. A V4 on the other hand is a better engine to fight with a pack of riders because of its power advantage.

Mat Oxley wrote up a fantastic article on the benefits of a V4 and the benefits of an inline four in MotoGP. Why V4 MotoGP bikes are better in battles

Just like Sigcrazy7’s video Mat’s article does a good job explaining the pros and cons of each design. Mat is an Isle of Man TT winner and one of my favorite moto journalists and authors. I cannot believe his book Stealing Speed has not been made into a screen play yet.

Very well done video, thank you for sharing it. I teach Engineering Mechanics, and many of the concepts in the video are covered in my class. In fact, we're talking about force couple moments (what he calls a "rocking couple") tomorrow. I may show part of this video to help illustrate the point.