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Discussion Starter · #1 ·
So I installed a SC Project S1 slip on + the 2-1 mid header. After installation I noticed a slight drop in low to mid range power/torque. I Love the look and the sound of the new system so switching back to the stock exhaust wasn't an option. And before installation I was told that I'd be given an engine warning light as the exhaust valve has been disconnected and removed. I never received such a warning light and that got me curious to what might be the reason behind this?

Link for your reference

Now reaching out to hopefully get some help.

#1 Figure out why the engine lost some of its juice in the low/mid range?
#2 What could I possibly do to regain some of the loss experienced?

Maybe someone else has expereinced something similair after installing a slipon?

As I have no real clue of what's actually causing this loss of power I don't want to speculat in possible solutions. So I'll just leave that to you... Tho I came across an interesting video on YT the other day regarding stock exhausts on modern motorcycles. And like the 939 manufacturers often use exhaust valves to controll and maintain a sufficient pack pressure. So a theory of mine is that when I got rid of the mid header and replaced it with SC Project 2-1 mid header it tampered with the back pressure in the exhaust system resulting in a drop in performance low/mid range?

All help is appriciated, though if you're just throwing random guesses out there to what the problem might be please instead take a seat right next to me instead and just watch the professionals handle this one ;)
 

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Not sure what the answer is but I can tell you that the exhaust valve on the 939 is primarily to meet sound restrictions and not for back pressure. I disabled mine with an electronic gizmo and suffered no loss of power and in fact made the bike run better.

I know that doesn't help, but hey, I work for the government so you shoulda expected that anyway.

Dave

Sent from my SM-G950U using Tapatalk
 

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The valve on the exhaust of these bikes is not ment for back pressure (Yamaha exxup system is ment for back pressure ). Its sole purpose it to meet noise regulations. You now have allowed the bike to breathe out easier but done nothing to allow it to breathe in easier. These bikes are not tuned great from the factory which is why you see a bunch of posts about jerky and popping and what not. Your best option is to flash with the T800, add a ralidbike tuner or try the Bazzaz tuner that everyone seems to have marked down to half price (I linked a listing today on a coiple FB groups that had the Bazzaz tuner , traction control tuner and quickshifter combo for like $450). Of you search around here (and/or hyperstrada.com) you will see a bunch of conversation about how that valve only messes with sound.
Another thing you should look into is the Starace RSR intake kit. It will allow for the bike to inhale equal to how it now exhales with the new exhaust. Add to that the tuner and everything would be optimized and run how you intended the bike to perform . These bikes are known to be jerky and have a power dip around 5k rpm due to fueling. You just exadurated that is problem with the exhaust. Fix the fueling and intake and yo will be happy . The other alternative is to I stall a lambda/O2 manipulator from comapanies like SC, Ralidbike fatduc. They are simple in line O2 manipulators . There is a used one on eBay from SC right now for $90. It looks like it's missing the knob so I would offer less but that's on you if you want to persue that route.

Fix the fueling.
 

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Discussion Starter · #4 ·
2 quick answers bearing fruit already it seems. MANY THANKS!!! Please if you have someone has some more specific suggestions of which T800 Map would best be suited for my exhaust please don't be afriad of sharing!
 

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You get 1 free map included in the price of the T800. If you intend on changing out the intake housing and/or filter soon then account for that as well. It's unusual to I stall an exhaust and a tuner without addressing the intake housing and/or filter. It will save you money in the long run. This is how drastic the intake housing is Right is OEM ,Left is the Starace RSR V2. Middle is Starace RSR V1 carbon nolonger available. 
 

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Discussion Starter · #6 ·
You get 1 free map included in the price of the T800. If you intend on changing out the intake housing and/or filter soon then account for that as well. It's unusual to I stall an exhaust and a tuner without addressing the intake housing and/or filter. It will save you money in the long run. This is how drastic the intake housing is Right is OEM ,Left is the Starace RSR V2. Middle is Starace RSR V1 carbon nolonger available. 
Alright, I had no clue the intake had such an impact on the performance! I guess any of these 3 you listed would together with a high flow filter would make the cut?
 

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Ducati performance used to make a housing . It is now hard to find but the Starace is superior. To order one you have to contact him directly through Facebook. It's a single guy making these.(Giuseppe Starace) There is also an option from MWR . I'm not a fan of them. It requires you to cut a hole in your air box and screw some self tapping screws through a sponge filter. That's not the reason I don't care for them though. My reason is, if you take a box and cut 2 holes in the top side and 1 hole in the bottom. Now blow air across the top 2 holes it creates a suction of the 3rd hole. That is bad. Dyno numbers show gains. Dyno numbers usually don't account for driving down the road and high speed air flowing over the top of the air box. I might be crazy but that's my logic on their design. The only other option now is the one on the left. That is the one that is redially available now through Giuseppe.
 

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Discussion Starter · #8 ·
Ducati performance used to make a housing . It is now hard to find but the Starace is superior. To order one you have to contact him directly through Facebook. It's a single guy making these.(Giuseppe Starace) There is also an option from MWR . I'm not a fan of them. It requires you to cut a hole in your air box and screw some self tapping screws through a sponge filter. That's not the reason I don't care for them though. My reason is, if you take a box and cut 2 holes in the top side and 1 hole in the bottom. Now blow air across the top 2 holes it creates a suction of the 3rd hole. That is bad. Dyno numbers show gains. Dyno numbers usually don't account for driving down the road and high speed air flowing over the top of the air box. I might be crazy but that's my logic on their design. The only other option now is the one on the left. That is the one that is redially available now through Giuseppe.
Thanks! Yea I actually already reached out to him earlier, waiting for answer back.
 

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Discussion Starter · #9 ·
Ducati performance used to make a housing . It is now hard to find but the Starace is superior. To order one you have to contact him directly through Facebook. It's a single guy making these.(Giuseppe Starace) There is also an option from MWR . I'm not a fan of them. It requires you to cut a hole in your air box and screw some self tapping screws through a sponge filter. That's not the reason I don't care for them though. My reason is, if you take a box and cut 2 holes in the top side and 1 hole in the bottom. Now blow air across the top 2 holes it creates a suction of the 3rd hole. That is bad. Dyno numbers show gains. Dyno numbers usually don't account for driving down the road and high speed air flowing over the top of the air box. I might be crazy but that's my logic on their design. The only other option now is the one on the left. That is the one that is redially available now through Giuseppe.
Everything has been ordered now, new T800 unit, the RSR airlid together with Sprint race filter. Very excited to how this turns out! Although I'm currently stuck onboard a cruise ship outside Miami, FL. And got another 2 months onboard till I get to go home again :cautious: But I'll DM you when everything is in place and let you know how it turned out! Thanks again!
 
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