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HI guys anyone shed some light on this for me.

Helping my brother do he's annual service on he's Tamburini
and he's not sure about the position of the variable stacks when
we removed the airbox.

He was thinking from memory they should be sitting in the down
position when with the bike not running but they are sitting up?

Thanks Rob
 

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They default to "up" as they are actuated by vacuum from the engine. So when the bike is disassembled (airbox removed) with the engine obviously off, they will be elevated up. When the bike is started they drop down in contact with the induction system.
So finding them elevated or up is what's to be expected when you remove the airbox.
 

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?

So Dave, if the default position is up (no vacuum) when is it the down position?
Because at full throttle and high RPM MAP goes close to zero
And what is the transition RPM/vacuum reading where it moves?

Being a student of carburation/fueling, I know about E. Weber's Rule ......nothing within 1 1/2 D of the airhorn
The TSS violates that rule

>:)
 

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Perhaps I didn't make myself clear.
The engine off default position for the TSS is up.
The engine on default position is down from idle to 10,000 at which point the velocity stacks of the TSS lift to the up position where they stay until the revs drop below 10,000 rpm again.
Actuation of the TSS takes a fraction of a second and is not progressive.

From one of the better articles on the TSS, in case anyone is interested:

Torque Shift System
Variable-length intakes such as the MV Tamburini’s Torque Shift System make us think of Formula One or of the last of the racing Mercedes 300SLRs, but the concept is useful wherever engine torque must be maximized across a range of rpm.
First, some physics. When a piston drops on its intake stroke, a deep vacuum of about half an atmosphere is immediately created in the intake tract. This propagates from the piston crown toward the intake’s open end–the bellmouth–at the local speed of sound (fast!). When it reaches the end, atmospheric pressure rushes in to fill that partial vacuum, creating a reflected pressure pulse that crashes back down the intake pipe as a wave toward the valves. If our wave returns to the cylinder just before the intake valves close, the pressure in that wave will be added to the pressure in the cylinder, making a denser charge that equals higher combustion pressure and increased torque.
Often there is not room on a motorcycle for intake pipes of the necessary length, so the designer will allow the intake wave to make two or more trips up and down a shorter intake pipe. Each reflection of the waves loses some of its intensity, but compromises are the engineer’s stock in trade.
By using an intake pipe of ideal length for the desired rpm, a torque gain of the order of 10 percent may be achieved–but only across a limited rpm range. To have both a robust midrange (the Tamburini’s peak torque on the CW dyno comes at 8700 rpm) and strong top end calls for having two different intake lengths. This is just what TSS delivers. The MV’s four throttle bodies have short, permanent bellmouths suited to top-end power, but a set of moveable extension bellmouths is carried on a pair of linear bearings. Below 10,000 rpm, these extensions are in place, creating a longer intake tract that boosts torque. Above 10,000 revs, a Pierburg pneumatic actuator (run on engine vacuum) snaps the extensions up and out of the way, shortening the intake tract to boost breathing and thus power on the top end. This is a two-state system–it is not progressive–as the extensions are moved in or out of use within 0.15 of a second.
Because the change of intake length is carried out at an rpm between peak torque and peak power, where the engine’s torque is less dependent upon intake length, torque at the “shift” point does not change greatly.
A similar two-state variable intake length system was used in Superbike racing by Honda on later RC45s, but this does not violate MV’s claim that TSS is a first for a production motorcycle.


The TSS worked similarly well. Torque delivery and bottom-end power is excellent, while peak output on the CW dyno was an impressive 154.4 horsepower, 3 more than the 1000 S. The 78 foot-pound peak torque was down 3 ft.-lbs., although the curve is more broad and peak comes 500 rpm sooner. Dragstrip testing conducted in extremely hot weather yielded a 10.22-second run with an excellent terminal speed of 142 mph. Road Test Editor Don Canet thought the E.T. could have been better, but there was some clutch slip in first gear, likely a result of the hard early life we gave the bike. Top-gear roll-on numbers were exceptional.


That is from the October 2005 issue of Cycle World.

And some pics of my Tamburini because everybody likes pictures.
Fully erect.....
 

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