Pneumatic Valves

[yzr-m1]

My "I'm not a team or manufacturing engineer..." disclaimer in place, I've never fully bought that theory.

I'm holding that disclaimer too! .... but I'll try and give my take on this

I don't have any links to back this up but I recall in early 2004 when Rossi first switched to Yamaha they were having tyre endurance problems that was resolved by moving to a more closely grouped firing order. In other fields such as electronics, pulsed power is a commonly used technique for delivering intantaneous pulses in excess of the peak power continuous rating although I would struggle to give a justification for comparing this with tyre technology. The reasoning in these cases is that high power pulses can be used along with a short recovery time and this does not adversly affect the lifetime of the part.

I have to admit the whole Garry McCoy thing about spinning the tyre and reducing temperature and wear confused the heck out of me at the time and I would love to see the physics that explains this!

[Rusty Bucket USA]

OK, if I forgot the tire thing and only remembered the power delivery thing about that Sepang pre-season test, I'll have to take that back... (anyone have their copy of What If I'd Never Tried It handy?)

The McCoy tire thing is one of these beautiful how-the-real-world-is-different-than-the-lab-and-the-theorists'-world reasons that I'm not a real engineer. I think the resultant theory was that there is actually a cooling effect on the core plies when the tire is slipping and spinning a lot compared to the heat generated by raw grip; the carcass doesn't have to twist and conform as much to the tarmac.

[TwoStroke Institute]

Rusty.
Two strokes never mix with anything else other than oil. Conventional 180 deg 2 up 2 down cranks generate considerable 'rocking couple' forces ie the crank is pulled forward on 1 end and pulled back on the other when the inertia from 1 rod being at 3 o'clock and the other at 9 o'clock. The ends of the crank trace a figure 8 and makes an hour glass shape when viewed from above. The 90 deg firing has 30% less rocking couple forces which is far smoother and helps traction considerably. Nothing new or revolutionary. WTF are these 'valve' thingys anyway

[phil]

WTF are these 'valve' thingys anyway

LOL...i came sooo close to asking that myself mr 2 stroke

[101N]

I think it would be worth our while to post the firing orders of a normal I4, a big bang I4, and a screamer I4. The way people talk about these firing orders I get the impression - I may be wrong - that there is a continuum of firing orders with big-bangs on one end and screamers on the other. It would help me to understand the 'big banginess' vs 'screamerness' of any given motor if you techies could help by filling in the following table. There are only 4x4x4x4 = 256 combinations some of which would not make sense because they would lose power.

1-----2-----3-----4
Conventional

Big Bang

Screamer

'09 R1 270-180-90-180

I can't tell from the SOUP article if the firing oder is 1-2-4-3 or 1-2-3-4. Is the new R1 270(1)-180(2)-90(4)-180(3)?

Thanks for the help.

[RatsMC]

This isn't going to help much but firing order isn't really significant in determining whether a motor is a screamer or big bang. It is all about the firing timing. In the simplest example, 1 and 4 fire at the same time and 2-3 fire at the same time.

[Rusty Bucket USA]

Exactly right, Rats... you got to it before I did, and well put.

A conventional firing order (at least, from my car knowledge) is typically 1-3-4-2. But could be just as easily engineered to 1-3-2-4. So, you wouldn't have the sequential 1->4 because it would be just way too unstable laterally, even in a Big Bang; they have to alternate sides of the centerline. You can see, then that your 256 possibilites are actually reduced to 12 or 13 (off the top of my head...) because you only have each cylinder firing once.

The next step is where the crankshaft is for each of those firing patterns. As mentioned before, even in an even-firing-order motor, you can have them positioned differently.

And then you're on to what Rats just mentioned, like two flat-twins working in tandem. The "Long Bang" gets in to how far off the "together" ones are from each other, and that's where the real top secret stuff is...

[RatsMC]

Just to complicate things more, the other component to consider is that in a 4-stroke, the crank must rotate twice for each time the piston fires. This is why it is so difficult to parse out what Yamaha has done based on the information provided. This is why I came up with two distinctly different interpretations both of which could be wrong.

[Rusty Bucket USA]

Well, then, now we can start talking about 6-stroke 3-cylinders...

[Albert]

After the thread touched upon the newly launched R1 I thought you guys (who can't get the paper version of MCN!) might be interested to read this stuff scanned from today's copy! (Especially as it answers a question or two about "Big Bang!")

[TwoStroke Institute]

Look at the pic of the crank it will still fire 1-3-2-4 just phased differently. Trust me it is still the rocking couple they phased out. They talk 'big bang' etc for PR as mentioning 'rocking couple' people would get the wrong impression or glaze over.Nothing is paired that would make the rocking couple worse.

[RatsMC]

It is definitely 1-3-2-4 but are the couples firing on the same stroke? If they are, it is a big bang set up. I can see the pics but can't read the text so I am not sure if they clarify in the article.

[101N]

I don't think any couples could be firing together with this pattern: 270-180-90-180. I thought the idea behind this system - little bang? - was to have each piston 90 degrees out of phase with the next firing piston. Somehow this - theoretically or in practice - reduces inertial torque.

If the firing order is 1-3-2-4 then the notation must be: 270(1)-180(3)-90(2)-180(4).

[jupiejupe]

sidenote: that is the uglest rear end yam has ever made, and those pipes are ready straight for the trash.

[Rusty Bucket USA]

sidenote: that is the uglest rear end yam has ever made, and those pipes are ready straight for the trash.

Funny how subjective taste is... I thought exactly the opposite (relying on the pictures, of course).

[TwoStroke Institute]

jupiejupe someone said the same thing to me today that this R1 looks so soft c**k it isn't funny.They obviously had no $$$ left over for the glamour makeover
Rats nothing is paired a true 'big bang' engine would have had 2 crank pins at 0 deg and 2 at 90 deg so 1 cyl fires and 90 deg after the next fires then an interval of 270deg.This new R1 is the screamer or even 90 deg as someone already stated. Phil Irving did similar things with old Brit parralel twins back in the day, he picked 76 deg firing interval and Harald Bartol did the exact same thing with the KTM 250.So in reality Yamaha is just catching up . NO inertial forces are actualy reduced just the NET resultant forces by the phase shift (or out of phase forces).
I'd still love to know what these valve thingy's are..........................................

[phil]

this topic is excellent mr 101N, the best in the short history of this forum IMHO.
its nice to get beyond traction control, tyres, pedrosa's personality and stoners ability.
top marks all round you boys know your stuff.

[RatsMC]

I don't think any couples could be firing together with this pattern: 270-180-90-180. I thought the idea behind this system - little bang? - was to have each piston 90 degrees out of phase with the next firing piston. Somehow this - theoretically or in practice - reduces inertial torque.

If the firing order is 1-3-2-4 then the notation must be: 270(1)-180(3)-90(2)-180(4).

I think you are right. I am really not getting why I, or anyone else should care about this though. If this isn't, in fact, a big bang configuration and it appears that it isn't, I don't understand why it is relevent. I know Yamaha wanted to be able to run a big bang motor in WSB but wasn't allowed unless it was done in production as well so I thought this was their approach to that but it doesn't appear to be the case.

[Albert]

I can see the pics but can't read the text so I am not sure if they clarify in the article.

I've resized the image a little Rats, but if I go too big it cuts part of it off when I post it.
I've posted it via a different host as well -- is it any better for you now?

The only wording below the pictures (which I inadvertantly cut off) was (Crank image) An in-line, four cylinder crankshaft, but not as we know it: Yamaha's staggered firing order.
(Inlets) New R1 retains the height-adjustable air inlet funnels.

[Rusty Bucket USA]

I'd still love to know what these valve thingy's are..........................................

I think they keep the oil out of the fuel....



In all seriousness, everybody, this guy is now the "official" resident engine expert!

[Gustav O]

WTF are these 'valve' thingys anyway

I know I have a valve in my toilet. That´s about the best place for them i reckon.

[RatsMC]

I've posted it via a different host as well -- is it any better for you now?

That was the problem. Despite working in IT, I don't use a computer at home so I am reading this at work and many image hosting sites are blocked

I could get the image on my phone but the text was too small to read.

Thanks much.

[101N]

FYI: this topic caught my interest so I did an Amazon search and came up with a book entitled "Motogp Technology" by
Neil Spalding. You can search inside the book and read a lot about big bang technology and its effects on tyre wear. There are some informative illustrations too:

http://www.amazon.com/MotoGP-Technology ... 070&sr=8-1

I will buy this book but I want to find out how Krop can get credit when I do. Do any of you know if there a link to Amazon on this site or a link to that book specifically? TIA.

[RatsMC]

That is a brialliant book. It is really the definitive source of technical info.

Krop used to have an Amazon store but I can't seem to find it anymore.

Added: found it. Had to do a Google search as it doesn't appear to be on teh main site anywhere.

http://astore.amazon.com/motogpmatters-20

Spalding's book is there for less than USD$20

[101N]

Thanks Rats. I bought the book using the link you provided.

I'm gonna be a big bang expert:)

(Krop may want to get that Amazon link somewhere prominent on the site.)