Pneumatic Valves

[8 dirt]

Thanks guys. I dig learning about this.
May I get a little off topic?
Why doesn't anybody else make a desmodromic engine? Patents? Thanks again. 8 d

[Albert]

Thanks guys. I dig learning about this.
May I get a little off topic?
Why doesn't anybody else make a desmodromic engine? Patents? Thanks again. 8 d

As far as I understand it there isn't a specific "Ducati held" patent on the desmo system!
Honda made two engines when they decided that they need more umph than the spring valve could provide.
One was a Desmo the other was the Pneumatic version that they race now!

No idea why they chose one over the other!

[TwoStroke Institute]

Corprate pride no doubt. Desmo's were first used in the 50's in Mercedes/Auto Union/Some German car for sportscars and F1, but for some unbeknown reason fell out of favour.More than likely spring technology improved and desmos considered to costly to produce. Ducati certainly seized on it and was convinced of the advantages.Not sure what the desmo rev ceiling is but it is far inexcess of any spring and raising the rev ceiling is the easiest way to a HP gain.

[Rusty Bucket USA]

I remember Dr. Krop bringing this up last year and linking to this page... As Wikipedia pages go, this one is pretty informative:
http://en.wikipedia.org/wiki/Desmodromic_valve

[RatsMC]

I believe that the primary reason that no one else picked up the Desmo thing is that they are a pain in the ass to maintain and require regular adjustment which is far more complicated than adjust metal spring valve while the benefit to the average street car or bike was really minimal.

[8 dirt]

Thanx everybody.
This is good shit.
Write on!
Cheers. 8 d

[Albert]

Thanx everybody.
This is good shit.
Write on!
Cheers. 8 d

There's a very good article here on Soup from 17 December 2007 with some explanations from Yamaha's Masao Furusawa.

[8 dirt]

Thanks Albert!
Occasionally I realize my eyes have glazed over for a nanosecond as I'm reading. I know I'd get it if it was demo'd in open cut-away.
It is clearer tho. Best at ya. Sometime tell us of NW Cumbria. Do you have rain yet? It's gray and on/off drizzle rain today in Puget
Sound. Happy Equinox! On to the Solstice!

[Albert]

Sometime tell us of NW Cumbria. Do you have rain yet?

We have rain pretty much every day!

From where we live we can look across at the Isle Of Man.
If we can see it - it's gonna rain!
If we can't see it it's pi$$ing down!

[airmaxindia12]

The amount of seat tension required to keep a coil sprung valve under control results in greater peak lift loading, with added stress to the entire valve train as a result. Pneumatic systems, sharing a common reservoir of pressure retain a more static level of force, controlling the valve effectively, without any attendant peak lift load increase.

[RatsMC]

Well, that's the weirdest, most pertinent spam I've ever seen

[Oscar]

I suspect the major problem with having pneumatic opening is the need to open the valve very, very quickly and to a high lift, overcoming the valve inertia which at these opening speeds is considerable, even with titanium valves. Basically (as I understand current performance technology), you need a real 'smack down' effect to create a shock wave that combats the residual pressure in the cylinder and accelerates the air mass from a somewhat bowl-shaped inlet port. Closing is a different dynamic, with a soft (relatively) landing desirable - a good match for pneumatics.

[Kropotkin]

Well, that's the weirdest, most pertinent spam I've ever seen

Agreed! If only all spam were this useful! I'm going to let it stand as a reward!

[TwoStroke Institute]

......and so it should stand, the IT desk would have gone off like the lady at 1.15(someones mentioned pneumatic valves on th net) and a good time to add a Monty Python sketch

[kkronja]

The only real life trouble with the '09 R1 (not so new eh...) is that it simply isn't a bike good for racing-all that "techno advertising" falls in the water if you compare it to the '08 R1, not only the dyno results, but even better to put both the engines on the weight scales- pseudo "bigbanger" has a very heavy crankshaft and cases that really makes going around the corners more difficult -they did it probably to be on the safe side, I remember when in '94 Yamaha offered some privateers a YZR500 big-bang engine(eh, the good ole times), most of them declined because its uneven nature put a bigger strain on engine cases making them less durable...
furthermore rear grip is more affected by the not so good rear shock linkage, then by the supposedly more tractable engine... all the SBK teams ditch the stock linkage and replace it with YEC or Graves kit parts, but if you are in Superstocks you're not allowed to do it-you can also add a very bad airbox design to that, also something you cannot touch in the SSTK... the result is that there isn't a single Yam in the Superstocks today...
I've tried to work with that bike throughout the '10 season, but it ended frustrating both on the straights and in the corners, no matter what we did...maybe it felt like being a Preziosi for a moment:-)

If you put a full blown YEC superbike engine (the "mere mortal" spec), you get faster, but there is still an occasional stock BMW or Kawa that will pass you on the straight...LOL

bring on the new one, please...

p.s. I also strongly agree that the motoGP bikes dont have to have any valves at all...'twas better that way

[JanBros]

p.s. I also strongly agree that the motoGP bikes dont have to have any valves at all...'twas better that way

I wouldn't go that for : nothing against a good exhaust valve, it's the intakes we don't need