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post #1 of 23 (permalink) Old 06-29-2005, 07:13 PM Thread Starter
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Desmo?

Ok.....newb question.....what exactly does desmo mean?
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post #2 of 23 (permalink) Old 06-30-2005, 04:40 AM
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No springs. The valves are opened and closed by a cam.

Here's a link http://www.ducatitech.com/info/desmo.html
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A few ccs short of a full litre.
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post #3 of 23 (permalink) Old 06-30-2005, 04:52 AM
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desmo is short fot desmoquattro, which is a technology ducati employs in their engines. Its a type of valve train. I'll try to explain.

The "classic valve train is the pushrod style. A series of rods ride on the cam shaft which is located in the "V" of the engines. The rods transfer the energy to the top, but in the opposite direction, so its reversed by a lever called the rocker arm. The rocker arm opens the valve. A spring closes the valve. This is the standart chevy engine. The problem is that all these parts in the valve train weigh quiet abit and thus give you a low red line.
Also there is the concept of valve float. At a high enough RPM the valve open very fast. So fast, that the spring cant close it fast enough, leaving an unsealed combustion chamber when the plug fires. So the higher RPM you want to run, the stiffer spring you need, the more power you are wasting to compress this spring.
Enter the overhead cam. Put the cam over the valve and let the valve itself ride on the cam (ok with a lifter, but lets forget about those), get rid of pushrods and rocker arms, so mass is lighter, but there is still the spring problem.
Enter the desmo. Use 2 rocker arms. one opens the valve, the other one closes. No springs. The theory goes, that there is no valve float, no power wasted on compressing springs. Sounds great no?
so how come ducati's put out less power, and have lower red lines than their jap counterparts? well, becouse all those crasy rocker arms added mass to the valve train.
Also now you got not one but two rocket arms to shim up, and the shims counteracting each other. Thats 2 rocker arms per valve*4 valves per cylinder * 2 cylinders. 16 rocker arms. So maintanance is quiet abit more intensive. valves must be shimmed every 6k miles.

Duc owners for the most part swear by this concept. And I gotta admit its pretty cool looking, and if you take the plugs out of the engine, you can spin the crank shaft with your fingers. Which is just awesome!




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post #4 of 23 (permalink) Old 06-30-2005, 04:58 AM
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post #5 of 23 (permalink) Old 06-30-2005, 05:24 AM
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Quote:
Originally posted by ZX6R1033
.
?

No valve float. Tolerances are closer. The clearances are actually reduced because valve seats wear and adjustments are made by changing openers and closers (shims).

A few ccs short of a full litre.

Last edited by mac020; 06-30-2005 at 05:35 AM.
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post #6 of 23 (permalink) Old 06-30-2005, 05:28 AM
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Quote:
Originally posted by mac020
?
!




( I said something, then I realized how stupid it sounded, to I deleted it. )



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post #7 of 23 (permalink) Old 06-30-2005, 05:29 AM
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Quote:
Originally posted by ZX6R1033
!




( I said something, then I realized how stupid it sounded, to I deleted it. )
You know how many times I wished I could do that in real life?




-- Thats Just The Way I Roll

"Do what you can, with what you have, where you are".
-—Theodore Roosevelt

"In war there is no substitute for victory."
---Douglas MacArthur, General

"Beware of those in whom the urge to punish is strong".
---Johann Wolfgang Goethe


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post #8 of 23 (permalink) Old 06-30-2005, 05:33 AM
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Quote:
Originally posted by ZX6R1033
!




( I said something, then I realized how stupid it sounded, to I deleted it. )
o

A few ccs short of a full litre.
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post #9 of 23 (permalink) Old 06-30-2005, 07:06 AM
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Quote:
Originally posted by Vash
You know how many times I wished I could do that in real life?


Just mumble a lot... if it still sounds intellegent when you hear yourself say it, repeat yourself louder when everyone else asks what you said.



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post #10 of 23 (permalink) Old 06-30-2005, 09:02 AM
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Quote:
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You know how many times I wished I could do that in real life?
Me 2!

A few ccs short of a full litre.
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