Crossplane crank

I would imagine the crank would be produced using conventional methods. Casting is casting basically. Even though the 'big bang' crank is different to a conventional crank, it isn't a really extreme piece of engineering.

It would just involve some different machining processes after the initial casting process.

I think the biggest issue Yamaha had with it all was their oversight on how critical the balance in the shaft would transpire into how the engine felt in the bike...... I think I read that they made a few mingers.

Sorry I cant elaborate any further at the moment. I work in an engine component factory which includes forging, heat treating and machining in many of our processes. We do not however do crankshafts, and anything I commented on now would just be my thoughts.

I will however have a chat to my engineer and try and dig a bit further into it for you.

Material wise, and this is just a kind of 'norm'. Here is a snippet off the good 'ol Wikipedia.

'Crankshafts can be forged from a steel bar usually through roll forging or cast in ductile steel. Today more and more manufacturers tend to favor the use of forged crankshafts due to their lighter weight, more compact dimensions and better inherent dampening. With forged crankshafts, vanadium microalloyed steels are mostly used as these steels can be air cooled after reaching high strengths without additional heat treatment, with exception to the surface hardening of the bearing surfaces. The low alloy content also makes the material cheaper than high alloy steels. Carbon steels are also used, but these require additional heat treatment to reach the desired properties'.

Thanks also for this thread [and great website].

I see that this (four cylinder) cross-plane crankshaft does not have the primary balance of the standard flat-plane crankshaft, because it has "rocking couples". Is this a problem for the Yamaha engine ~ does it feel 'vibey' : or are the rocking couples small enough to be unbothersome for the rider at cruising speeds?

Or does Yamaha put in a single engine-speed balance shaft to counter the primary vibes? [I can see that such a balance shaft ought to give near-perfect primary balance : and the cross-plane design itself also gives inherent cancelling of the secondary forces, about as good as a straight-six.]

On a second point, you've confused me about the zero inertial torque [in that earlier article] found in the flat-plane V8 [versus the usual V8].
I can see that it is so ~ but would not that apply just as much in the conventional cross-plane V8 : since in both designs, at every 90 degrees of rotation, 4 pistons are stationary and 4pistons are at maximum speed? [i.e. both V8 designs are essentially four V-twins of 90 degrees.]

And thanks for the calculations on the inertial forces of the pistons ~ they are surprisingly huge in relation to the cranking forces of the power pulses.
Ducati twins and Triumph triples are looking better and better !

You were confused because I got that wrong.. It was one of those extra pieces of info I thought was interesting which I discovered and used without thinking about it hard enough - you're absolutely right, both have zero inertial torque (or close to zero as the piston movement is not symmetrical).

I'll take that out of the feature.

The R1 does have a single, counter-rotating balance shaft, and Yamaha's engineers said the development of this was exceptionally complex, which is not hard to believe.

Regarding the inertial torque forces, as one automotive engineer said to me, "Engines are surprisingly violent things!"

Kevin, I think a man of your standing in the motorcycle community should adopt the Fonz's position when you become convinced that you thought you were wr... wrr... wr...

Just snap your fingers and snog some luscious thing!

You have to say engine design is decisions or choices about trade-off's. It must be fun being an engine designer as the challenge is far from straight forwards but everyone judges the results of your decisions.

Knowledge and know how is far more available these days to designers, say compared to even the 90's, but diversity seems more prevalent or is that engineering ego is allowed it's freedom today?

New model types, styles and categories are very much driven by marketing departments at most companies, with the possible exception of Honda. Of course there's a certain amount of two way information exchange, with engineers letting marketing people know what's new and can be done, but on the whole it's the marketing departments who define new models. When engineers are given their head, as at Honda, sometimes it works very well, as with the Fireblade which the marketing people resisted all the way (no one's going to want a 900 when the other superbikes are 1000-1100cc!), and sometimes you get things like the DN-01, which is fascinating from en engineering point of view, but no one wants it.

Behind all this is that motorcycling has become very much a leisure pursuit, where it used to be utility, so it's much more open to interesting and different types of bike rather than run-of-the-mill efficient but dull ones.

I'd really like to get more info on the motoczysz c1 engine. I would like to see the design of their counter-rotating crankshaft.

http://motoczysz.com/motorcycles/c1_prototype

From what I've managed to glean from the net, the Motoczysz C1 is a 15º v-configuration, with 3 camshafts. I think I could see the outline of a cam chain tensioner on the left side of the engine.

I can see a dry clutch at the front of the engine, so presumably the transmission is all directly beneath the crank.

I read the thier previous attempt had the cranks stacked, which made the engine taller. If I had to guess, I'd say the narrow V angle may have been chosen so the mating contra-rotating cranks can be on a horizontal plane & reducing engine height.

I've no idea how they've arranged the crank pins, but since the crank is divided, 180º is a logical choice. If I had to guess, it would be that each pair of crank pins is arranged at 180º, but then the plane of the front pair of crank pins could is at 90º to the rear pair. The front pistons would then be at max speed while rear pistons are at TDC & BDC respectively (& vice versa)

I've only recently discovered the existence of the Motoczysz C1 (I used to own a BMW C1, but that another story) & couldn't help thinking that BMW didn't just share the name for their scooter: the countershaft sprocket sharing the swingarm pivot is also on one of beemas dirt bikes (BMW G650 X). Also Motoczysz's central front shock reminds me of BMW's telever. Very interesting machine...

Good way of thinking about it, and in fact you can replicate that by holding the front brake on and letting out the clutch partially with the bike in gear. What you're not getting though is the rearward weight transfer you have when accelerating, which counters the suspension extension to some degree.

Angle the swingarm the other way and you'd get chronic squat problems, which sounds more like a medical issue...

Right again, and I've seen it on dataloggingsy stems, front and rear both extend in acceleration, but the front does it by more (right up until the wheel is off the ground - reckless behaviour, obviously)