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I was just reading the Dream Rides article in Motorcyclist and they mention that the no-redline tachometer is a signature of Massimo Tamburini...This is on the MV Agusta F4 as well as Ducati's, as far as I know.

What's the history/ reason behind this? Just to force the rider to ride by feel/ listening to the engine? Just curious..





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If the max engine speed is regulated by the engine control unit, isn't it just academic ? A romantic carry over from old tech ?



red_ryder said:
I was just reading the Dream Rides article in Motorcyclist and they mention that the no-redline tachometer is a signature of Massimo Tamburini...This is on the MV Agusta F4 as well as Ducati's, as far as I know.

What's the history/ reason behind this? Just to force the rider to ride by feel/ listening to the engine? Just curious..





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I think it's more along the lines of a SBK being for racing and racers don't need redlines I would think.

A few times last season I misshifted and the bike was at 11K. The top safe rpm is supposed to be 10K on my 916 I believe. So unless the tach is wrong.....

At 150mph if I downshift into 2nd gear will the ECU will prevent my motor from revving to 15000? Cool thing to try when I get my slipper clutch I guess. :)
 

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no it won't stop it from revving to 15,000,it will only stop it fireing the sparkplugs
 

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+1

kaos said:
no it won't stop it from revving to 15,000,it will only stop it fireing the sparkplugs
 

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-raises hand- Oooh, oooh, I know this one! Actually, the fact that the F4 doesn't have one is pure styling and possibly a nod to the Tamburini connection. But the fact that some/most Ducs don't is actually based in theoretical mechanical physics.

What redline actually represents is the point at which valve float becomes a problem. In a motor with valve springs, the cam(s) open the valves and the force from the valve springs closes them. As the motor spins faster, the valves open and close at ever increasing extreme rates of speed. Eventually, the force of the springs is not enough not close the valves completely before the next stroke cycle comes around and you have valve float. At that point, the combustion chamber isn't sealed, intake and exhaust don't take place properly, valves can even remain open far enough to slam into the piston on upstroke, and basically all internal combustion processes go to sh!t in a hurry.

On a motor with desmodromically operated valves, there of course are no valve springs. One cam opens the valves and another cam closes them. Theoretically, as fast as you can open the valve with one cam, the closing cam also shuts it. So, you never get valve float, and therefore have no valve float dictated redline.

Now, I say theoretically because there are other factors to redline such as friction mitigation, piston velocity and g-forces during BDC and TDC (the piston is a heavy slug that has to be accellerated and decellerated under EXTREME forces because of the speed of up and down movement). So, even with desmo motors, there is a practical limit to how fast the motor can spin. And the ECU is programmed to retard or eliminate ignition at a certain rpm to prevent these other problems from arising, which becomes the unindicated redline but very real rev limiter. But the fact that there is no possible valve float means that the traditional "redline" factor is not present.

So, sort of as a subtle slap in the face of the competition, it is my understanding that many Ducs do not show a redline in a reference to the desmo actuated valves. Like I said, they still have a very real practical limit that the rev limiter enforces. But, it's a clever indicator that Ducs are something special. IIRC, the MVs have more traditional valve springs. But, perhaps the F4s don't have an indicated rev limiter sort of as a nod to Tamburini?? Or maybe it's just marketing so that it falsely appears that the highest rpm indicated is how high the motor can rev??? Sort of the, "ooooh...look daddy, the speedometer goes to 200" effect.

edit: oh, and yes, racers need an indicator for redline more than anybody else does. Many racers add a redline or better yet a shift light. Especially if they electronically remove the rev limiter for safety and overrev reasons. Gotta know if you are about to grenade your motor when you go to heel it over at the end of Daytona's banking!
 
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Well, sort of-

The red line indicates the engineer's warning of problems ahead. It doesn't necessarily have to do with valve float. ( In fact, where on earth did that one come from...must be about twenty years ago. I haven't heard of valve float problems from any race engineer in years, so that can't be the reason for a red line, eh ?) It is addressing the mechanical limits of the engine. And don't go dissing valve springs. Desmo is fun and Desmo is a lot of things, but no one has demonstrated that it is superior to valve springs. ( It is simply Ducati's "brand" way of doing, and as technical writers say, they make it work.)

And sometimes a tach it isn't even necessary. On the pre-twin spark Monster engines, you couldn't overrev them because they would just run out of steam, and Monster riders would just accelerate until there wasn't any more...and then shift. Ducati later made an accessory tach available but it was there for $how. ( I'll sell you mine, cheap.)

If you want to have some fun, take whatever redline is available to you and back calculate that to the piston speed. Thats where the limits of material science get to be interesting. Piston speed is where the fun begins as all of those loads of accleration have to be stopped and turned the other way. It makes things interesting.

Lastly, painting a higher redline on your tach is a nice way of mind f**king with the competition or the posers. ( A big redline means as much as the top speed painted on your speedo. Utterly meaningless.)

Ah...one other thing. I noticed on superbikeplanet.com today that the new Yamaha 600 doesn't rev to the limits shown on the tach, and there doesn't seem to be much concurrence between the PR office and Yamaha engineering as to why it won't. Bad tachs ? Bad settings on the engine control ? WTF ? But it won't go to 17,500 as they advertise.


nathanTX said:
-raises hand- Oooh, oooh, I know this one! Actually, the fact that the F4 doesn't have one is pure styling and possibly a nod to the Tamburini connection. But the fact that some/most Ducs don't is actually based in theoretical mechanical physics.

What redline actually represents is the point at which valve float becomes a problem. In a motor with valve springs, the cam(s) open the valves and the force from the valve springs closes them. As the motor spins faster, the valves open and close at ever increasing extreme rates of speed. Eventually, the force of the springs is not enough not close the valves completely before the next stroke cycle comes around and you have valve float. At that point, the combustion chamber isn't sealed, intake and exhaust don't take place properly, valves can even remain open far enough to slam into the piston on upstroke, and basically all internal combustion processes go to sh!t in a hurry.

On a motor with desmodromically operated valves, there of course are no valve springs. One cam opens the valves and another cam closes them. Theoretically, as fast as you can open the valve with one cam, the closing cam also shuts it. So, you never get valve float, and therefore have no valve float dictated redline.

Now, I say theoretically because there are other factors to redline such as friction mitigation, piston velocity and g-forces during BDC and TDC (the piston is a heavy slug that has to be accellerated and decellerated under EXTREME forces because of the speed of up and down movement). So, even with desmo motors, there is a practical limit to how fast the motor can spin. And the ECU is programmed to retard or eliminate ignition at a certain rpm to prevent these other problems from arising, which becomes the unindicated redline but very real rev limiter. But the fact that there is no possible valve float means that the traditional "redline" factor is not present.

So, sort of as a subtle slap in the face of the competition, it is my understanding that many Ducs do not show a redline in a reference to the desmo actuated valves. Like I said, they still have a very real practical limit that the rev limiter enforces. But, it's a clever indicator that Ducs are something special. IIRC, the MVs have more traditional valve springs. But, perhaps the F4s don't have an indicated rev limiter sort of as a nod to Tamburini?? Or maybe it's just marketing so that it falsely appears that the highest rpm indicated is how high the motor can rev??? Sort of the, "ooooh...look daddy, the speedometer goes to 200" effect.

edit: oh, and yes, racers need an indicator for redline more than anybody else does. Many racers add a redline or better yet a shift light. Especially if they electronically remove the rev limiter for safety and overrev reasons. Gotta know if you are about to grenade your motor when you go to heel it over at the end of Daytona's banking!
 

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My understanding of why there is no Red-line is that as a bike that is built to be 'raced' rev limits are variable from bike to bike (state of tune etc) and so this was why they had no red-line, this has carried on as a link to the racing heritage. :)

But the cynic in me says it's a cost saving exercise - so they could use the same tacho on a 996 and a 748......... ;)
 

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grendels_arm said:
17500 is the redline on the Yamaha? Wow. You like never need 5th or 6th gear. :)
Would imagine on such a 'peaky' motor you'd definitely need all the gears, in fact it would probably benefit from a 7-speed gearbox, presumably the final drive ratio reflects the 17500 rpm limit.

Reminds me of when I first got a bike, my Grandmother told me not to ride too fast, to be careful and to "only to use first gear".... :)
 

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jack said:
How did somebody take a picture of their dash at 320 kph?

Fast film. ;)






At start-up, the MV's turn on all the indicator lights - neutral, headlight, high-beam, turn signal, temp and oil-pressure warning - as well as "top out" the electronic speedo and tach.
 

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carful about that R6. I dont know about the new bike but I know that my R6 has a 15500 rpm red line, and hits the limiter somewhere around 16200. (its an 02 model) Granted I have done some tweaking on the bike but it will hit the limiter in the first five gears and red line in 6th. That is with stock gearing. I havent ridden the new R6 with the 17500 redline but its not really that much of a stretch top get 2000 more rpms. Maybe the bike isnt tuned out quiet yet or something but Im sure that that motor will turn out the 17500
 

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bevel450 said:
Ah...one other thing. I noticed on superbikeplanet.com today that the new Yamaha 600 doesn't rev to the limits shown on the tach, and there doesn't seem to be much concurrence between the PR office and Yamaha engineering as to why it won't. Bad tachs ? Bad settings on the engine control ? WTF ? But it won't go to 17,500 as they advertise.
Ironic, isn't it, that *that* spring-valve motor (and many, many others) will spin higher - a lot higher - than most desmo motors. Yet the myths of "valve float" and the "inherent superiority of the desmo system" still linger.

More ironic, perhaps, is the fact that thousands of desmo owners - with motors that rarely spin above 8,000 rpm's - will be adjusting valves at 6,000 and 12,000 mile intervals, while those with the more-rapidly spinning valve-sprung motors will adjust their valves at less frequent intervals.
 

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st2lemans said:
Desmo's not just about valve float. There is less frictional loss (due to only a weak return spring, and you can run more radical cam profiles, than with springs.

Tom
Absolutely true. In theory.

Slightly more aggressive cam profiles and miniscule frictional losses are insignificant factors on street bikes that make 90 RWHP or less (and that HP figure applies to well more than half the bikes Ducati sells).

EPA and Euro regs have more than a little to do with cam profiles. I'd love to see a graph that compares actual valve lift profiles vs. crankshaft rotation for street-legal bikes. I'd imagine the profiles on an Aprilia RSV-R, for example, are more radical than those found on most Ducatis.
 
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Well, my tach has a nice red line at 9,000 rpm which is quite bright and clearly visible. And, of course, totally useless because there's no point in going over 8,000 rpm.

But what I really like is you can barely see it anymore, but there's a small red 55mph mark in between the black 50 mph and 60 mph marks. When 55 mph was the law of the land, by law you had to have a 55 mph mark on your speedo, regardless of whatever the other markings were.

Bless their hearts, Ducati thought 55mph was b******t, so they used a different ink that looked nice and bright when in the showroom, but faded almost immediately in outdoor light.

Gotta love the Italians!
 
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