Yamaha R1 crank

Pretty much unique in all the world's inline 4-cylinder engines, the R1 has a cross plane crank.

Uneven firing, massive primary vibrations and added weight and complexity.

Who knew?

Greg Masters said:

Pretty much unique in all the world's inline 4-cylinder engines, the R1 has a cross plane crank.

Uneven firing, massive primary vibrations and added weight and complexity.

Who knew?

Click to expand...

Simple
1 It sounds ace
2 It sounds ace
3 Apparently it aids traction

Steve

steve hughes said:

Simple
1 It sounds ace
2 It sounds ace
3 Apparently it aids traction

Steve

Click to expand...

Indeed.

Whereas a flat plane 4 cylinder 4 stroke fires every 180 degrees of crank rotation, the R1 has a gap of 270 degrees in every two rotations enabling the tyre to recover grip.

Greg Masters said:

Pretty much unique in all the world's inline 4-cylinder engines, the R1 has a cross plane crank.

Uneven firing, massive primary vibrations and added weight and complexity.

Who knew?

Click to expand...

Hasn't it been around for many years ?
It does sound amazing.

Greg Masters said:

Indeed.

Whereas a flat plane 4 cylinder 4 stroke fires every 180 degrees of crank rotation, the R1 has a gap of 270 degrees in every two rotations enabling the tyre to recover grip.

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What's yout maths like Greg, how long does the tyre have to recover grip at
9k rpm?

Timolgra said:

What's yout maths like Greg, how long does the tyre have to recover grip at
9k rpm?

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Whatever the answer, it's even shorter as the rev limit is 13,750rpm

interesting thoughts

The idea is the bang - bang Pulse effect driving the wheel

Probably easier to imagine the scenario with a Ducati for example

The Bang - Bang - "gap" bang - Bang "gap" creates a pulse that helps break the surface tension on a wet road

That pulse isn't there in an inline 4 "generally" so once the tyre breaks traction it just gets driven on to a wheelspin

I know you can wheelspin a Big Twin

But I thought it was a good explanation

You would wonder how much heat is transferred to a valve seat on a 1200 Hex at full chat

Answer Any is better than none!

Originally done on the 500 two strokes, which were a bit vicious when they spun up.
I think tyre tech has improved no end since those days, and traction control has become very sophisticated, so it isn't so important with modern rubber and tech.
Isn't the cross plane so they can have a narrower engine?

Although the cylinders are in line with each other, it's a transverse four, not an inline four.
The engine layout reference is taken from cylinder orientation against the bike frame.
Hence, a BMW K100 is an inline four, but an R1 isn't.
The bloody Americans started calling transverse fours I-4s, quickly followed by our lazy idle bike rag journos, who doubtless thought it was "hip".

Even more piss boiling is the bike rags calling a Ducati V twin engine an L twin when it's just a 90 degree vee.

Quattroformaggio said:

a 90 degree vee.

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L....

Quattroformaggio said:

Although the cylinders are in line with each other, it's a transverse four, not an inline four.
The engine layout reference is taken from cylinder orientation against the bike frame.
Hence, a BMW K100 is an inline four, but an R1 isn't.
The bloody Americans started calling transverse fours I-4s, quickly followed by our lazy idle bike rag journos, who doubtless thought it was "hip".

Even more piss boiling is the bike rags calling a Ducati V twin engine an L twin when it's just a 90 degree vee.

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Not sure I agree with this logic but if as you say the designation of the engine depends on its installation in the frame then how can the Ducati engine be a V if one bank lays in the horizontal plane, maybe your piss is boiled without good reason?

Kevin Ash (RIP) provided a detailed article back in the day, but I can't seem to track it down now.

Instead, I have lifted this from another old biker forum exchange, where KA details the concept of inertial torque reduction: -

'' I'm a bike journalist and technical writer too and have looked into Yamaha's crossplane crank in detail, and the real reason they use it hasn't been touched on in this thread yet. There's a full feature on my own website at www.ashonbikes.com. The key to it is that in a flat plane crank all four pistons are stationary together, then accelerate, then stop again, all at the same time. If you take the crank and piston system in isolation and spin it (we'll have zero friction for the moment...), this means the pistons' kinetic energy is all transferred to the crank when they're at BDC and TDC, so at that stage the crank is spinning fastest. 90 degrees later all the pistons are at maximum speed, and that energy has come from the crank which in turn slows down. 90 degrees further on again and the pistons have stopped and crank's spinning faster. This is a sort of background cyclic wobble in the crank's rotation (but nothing to do with balance) which adds a fuzzy edge to the power delivery, and it IS noticeable by ordinary mortals on the R1, at least on the track. It's independent of the torque output from the engine's combustion and merely overlays it in a near-sinusoidal pattern with a net torque of zero.

In the cross plane configuration the pistons' accelerations cancel out - as one is speeding up another is slowing down, and the inertial torque (which depends on the mass of the pistons and conrods, not the crank) is almost zero (almost because the conrods have finite length and pistons spend longer in the lower 180 degrees than the upper).
The uneven firing intervals are simply a side effect, not Yamaha's aim, and do nothing to increase grip - Pirelli did some research on this a few years ago and could find no evidence of the Big Bang idea increasing grip.
The cross plane idea is not marketing guff, Ducati has been quietly enjoying the benefits with its 90 degree twins for years (almost zero inertial torque) which is why they've configured the MotoGP bike effectively as two V-twins side by side, and its a factor in several car engine designs. ''

Harley Davidson have had “Big Bang” motors forever, that’s how they get all that torque down. Yamaha started using the same principle in their 270 degree twin, (the TRX and TDM), which mimics a 90 degree V twin and now everyone is jumping on the band-wagon because it also reduces vibrations, it’s easy to build a balancer shaft or two into, it is nice and slim, easy to produce and aids traction too with the dwell between power strokes. Building a twin cylinder motor like this mens that, unlike a 360 degree and 180 degree parallel twin, the pistons never come to a dead stop at TDC or BDC. The flat plane crank in Yamaha’s 4 cylinder R1 and MT-10 has been around since about 2009 or 2010 and it’s a belter!

Oh, and don’t forget, BMWs flat twin is just a wide angle V twin

Greg Masters said:

Pretty much unique in all the world's inline 4-cylinder engines, the R1 has a cross plane crank.

Uneven firing, massive primary vibrations and added weight and complexity.

Who knew?

Click to expand...

Don't think so. At first glance, yes, but think again.
A Single Cylinder or parallel twin engine has horrible Primary vibrations coupled with, to a lesser degree, secondary vibrations.
A 180 degree crankshaft parallel twin has no primary vibrations, but a significant rocking couple and secondary vibrations.
A BMW style flat twin has neither primary nor secondary vibrations, but it does have a very significant rocking couple.
On 1200 on engines, BMW fitted a single balance shaft. ( They should have used 2 to remove the rocking couple completely.) Thus, they quartered the amplitude of the vibrations, and multiplied the frequency by four.
A "Flat 4" engine has neither primary or secondary vibrations, and no rocking couple.
A 4 cylinder single plane crankshaft engine has no primary vibrations but secondary vibrations.
A Vertical Twin engine with a 90 degree crank, or a 90 degree Vee twin have no primary vibrations because the 90 degree masses cancel one another out, as do the secondary vibrations. They do, however have a tiny rocking couple.
A 4 cylinder crossplane engine, just like the 90 degree vertical twin engine has neither primary nor secondary vibrations, and the rocking couple is cancelled out as well.
Thus, like the flat 4 engine, it has perfect balance, but uneven firing intervals.
Look at other posts to see why this is advantageous.

squibb34 said:

The key to it is that in a flat plane crank all four pistons are stationary together, then accelerate, then stop again, all at the same time. If you take the crank and piston system in isolation and spin it (we'll have zero friction for the moment...), this means the pistons' kinetic energy is all transferred to the crank when they're at BDC and TDC, so at that stage the crank is spinning fastest. 90 degrees later all the pistons are at maximum speed, and that energy has come from the crank which in turn slows down. 90 degrees further on again and the pistons have stopped and crank's spinning faster.

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I get the point but some of the pistons' kinetic energy is used to expel exhaust gases or draw in fresh charge or compress the fresh charge.

He also conveniently ignores the fact that for 270 degrees of the R1's crank rotation there is no power coming from any cylinder. The engine at that point must be slowing.

Myke Rocks said:

A 4 cylinder crossplane engine, just like the 90 degree vertical twin engine has neither primary nor secondary vibrations, and the rocking couple is cancelled out as well.
Thus, like the flat 4 engine, it has perfect balance, but uneven firing intervals.

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Sorry Myke, but this isn't right.

The R1 cylinder 2 and 3 are have crank pins 180 degrees apart. As per your example of a 2 cylinder engine, these would be accepted as primarily balanced.

But cylinders 1 and 4 also have crank pins 180 degrees apart. These cause a rocking couple (primarily imbalance) due to their relative distance from the middle of the crank.

Daffy said:

Not sure I agree with this logic but if as you say the designation of the engine depends on its installation in the frame then how can the Ducati engine be a V if one bank lays in the horizontal plane, maybe your piss is boiled without good reason?

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Why can't you see that the Ducati is a vee?
It's 90 degree vee twin, which just happens to have the front cylinder horizontal.

The transverse/longitudinal reference is not the engine's installation, but the orientation of the cylinders relative to the frame.
The Ducati is a longitudinal V, as opposed to a Guzzi being a transverse.

It's not my piss either, that's how it is.

longdog said:

Oh, and don’t forget, BMWs flat twin is just a wide angle V twin

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I take it that's a very poor snipe at me, but you're wrong, as it's a 180 degree horizontally opposed twin.

However, if we're having a pissing contest, the Zundapp KS750 "Flat twins" as used in the WW2 German Army sidecar outfits were actually very wide angle vees.
I can't remember if it was 170 or 174 degree vee, but they had just a bit more ground clearance than the BMW twins...look at a good head on picture and you'll see.

Quattroformaggio said:

Why can't you see that the Ducati is a vee?
It's 90 degree vee twin, which just happens to have the front cylinder horizontal.

The transverse/longitudinal reference is not the engine's installation, but the orientation of the cylinders relative to the frame.
The Ducati is a longitudinal V, as opposed to a Guzzi being a transverse.

It's not my piss either, that's how it is.

Click to expand...

I didn’t say it wasn’t a V, what I said was that your if your logic about an R1 engine not being an inline 4 because it sits across the frame is correct then a V with a cylinder in the horizontal plane must be an L.

By the way, its still an inline engine whatever way it’s mounted.

Greg Masters said:

Sorry Myke, but this isn't right.

The R1 cylinder 2 and 3 are have crank pins 180 degrees apart. As per your example of a 2 cylinder engine, these would be accepted as primarily balanced.

But cylinders 1 and 4 also have crank pins 180 degrees apart. These cause a rocking couple (primarily imbalance) due to their relative distance from the middle of the crank.

Click to expand...

Apologies. Nearly correct was I. But still perfect primary balance, though as you say, a large rocking couple. This may be cancelled out with counterweights, but I doubt if it is on one of these engines.