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Discussion Starter · #1 ·
Ducati recons the new exhaust valve on the 1098 inproves teh power delivery. Anyone looked at teh posted dyno graphs and noticed a large dip in torque just below 4000rpm? Is this an emmissions 'thing' - and what happens when this is removed.....
 

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had that on the my Triumph 955i at 4500 and you really noticed it. Would be interested in knowing the facts behind it. Seems to be a combination of engine design and fuel management. They said they "tuned" it out with later engine maps, to an extend you had a slight power blip happen at 4500
 

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Remember that a dyno test is done at WOT. I'm not sure if the exhaust valve opens up as a function of throttle opening only, or maybe it's throttle opening and RPM driven.

If the exhaust valve is wide open before 4000 RPM if the throttle is wide open, then the dip isn't due to the valve. If the valve suddenly goes wide open at 4000 RPM then the dip is most likely due to the exhaust valve.
 

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I thought that the Exhaust Valve is supposed smooth out power delivery, ala the EXUP valve on the Zook?
 

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Discussion Starter · #5 ·
More Exhaust valves

I've jsut seen same type of exhaust valve on the new Hypermotard using the 1100 Multistrada engine.

Exhuast on the jap fours are different. They alter the tuned length of the exhaust by opening or dredirecting the gas flow.

Anyone out ther want to disconnect the servo motor and wedge it fully open to see what happens?
 

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ducati exaust

i was told by my dealer that the valve in the exaust is only operational for 200rpm and it operates so as the noise can be lowered so as it will pass the european noise laws for an mot and it does not affect the power in any way ?
 
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