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Discussion Starter · #1 ·
Curious to know how the SET behaves... does it close based on throttle position, speed, or RPM??
Every time you start the bike you hear it squeek closed... But after you start the bike what happens?
 

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Discussion Starter · #2 ·
About being curious... no...
Running the bike this way... Straight headers right, so it would be pretty loud, but if you have fuel management one should be able to richen it up so as not to cause damage.

Do you know the answer Perry?
What does the SET do, and under what conditions...

My guess would be that at high throttle it opens all the way to allow max air to exit, but when is it closed or partially closed?
 

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Here's a quote from an article written earlier this year... :doorag:

"The two-into-one-into-two stainless-steel exhaust system features a catalytic converter as well as a butterfly valve to adjust back pressure to match the engine's mode. Suzuki's acronym is SET (Suzuki Exhaust Timing), and it provides more back pressure to improve torque at low rpm, opening as rpms increase. Suzuki says this helps provide strong low-rpm torque even though the M109R design favors mid-range and high-rpm power."
 

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Discussion Starter · #4 ·
Thanks Trouble_Is, appreciate the response. :bigthumbsup:

The part I am trying to figure out is the "Adjust back pressure to match the engines mode" statement.

The butterfly valve opens as RPM's increase, allowing more airflow, and closes as they decrease to restrict airflow. This restriction increases the back pressure at Low RPM's, which richens up the fuel mixture by allowing less air to flow in during Valve overlap, thus improving torque at low revs... That part I understand.

What I am trying to figure out is does the SET slowly open with RPM's solely? Or does the throttle position sensor factor in on what the butterfly valve does? In other words, If my bike is idling and I whack the throttle hard does the Butterfly valve open immediately all the way, or does it gradually open as the RPM's come up... :dontknow:

I was hoping that some of the guys who have been playing with their exhaust would know the answer to this but based on Perry's response, and the lack of others, I guess not. ::)
 

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JUtah said:
The butterfly valve opens as RPM's increase, allowing more airflow, and closes as they decrease to restrict airflow. This restriction increases the back pressure at Low RPM's, which richens up the fuel mixture by allowing less air to flow in during Valve overlap, thus improving torque at low revs... That part I understand.
I would think the stock ECM would be mapped to accommodate the SET allowing more or less airflow to prevent the mixture from richening or leaning out... if you have the stock intake and exhaust.
 

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it doesn't seem like the SET is fast enough to match quick throttle response. i'm glad mine got cut off.
 

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Discussion Starter · #7 ·
Medic1210 said:
I would think the stock ECM would be mapped to accommodate the SET allowing more or less airflow to prevent the mixture from richening or leaning out... if you have the stock intake and exhaust.
By far no expert on the topic (the reason I am looking for more info)... but from what I have read in days of scouring the web, Increased backpressure increasing Tq is a PERCEPTION but not reality. The richened mixture is what increases the Tq. The reason why people typically feel their motor has lost power when they change to a free flowing exhaust is that they are LEAN.

What all of the articles I read agree on is that back pressure in an exhaust robs an engine of power. When you remove back pressure from an exhaust you allow the cylinders to pull in more air during the Valve overlap, and make it easier for exhaust gasses to be expelled. More air in means you can cram more fuel in, coupled with the reduced resistance on the motor to expell the burnt gasses and you make more power.

When you increase back pressure you reduce the amount of Air pulled into the cylinders during valve overlap and richen the mixture. A richened mixture increases Tq. (Again no expert, just what I read). :dontknow:

Here is a link to one of the many places I read about this... http://hayabusa.org/cgi-bin/busa/ikonboard.cgi?act=ST;f=47;t=30981

So... IF the above is true then it would make sense that Suzuki closes the SET some at low RPM's to richen the mixture up and make more Tq... to give you that 3000 RPM pull when you are putting around town. Then as RPM's increase they open the SET to let it breathe and bring it back to a more balanced mixture... :dontknow:

This may explain why when I dyno'd my bike Peak Tq was around 3400 Rpms while Peak HP was around 6000... (I think that has been the case on most of the Stock dyno sheets I have seen. )

Phaed... did you notice any difference in your low end Tq with the SET removed?
 

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It's a butterfly valve, just like a throttle body, so I don't see why it couldn't open at least as fast as the throttle bodies when you romp on it :dontknow: Even if it's controlled electronically instead of directly by the throttle cable, we're talking milliseconds for the engine computer to do it's calculations and send a signal to the SET valve actuator :doorag:
 

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I disabled the SET on my bike but didn't remove it. I noticed quite a bit of difference when I romped on it at around 2500 to 3000. It would bog considerably. So, using the same reasoning as you are that the closed exhaust only enrichens the mixture, I set the first setting on my FI2000 (yes I'm still using that thing) up a couple of notches and gained back the snap in that rpm range. It seems to be running the same as before down low. But I think it may have leaned out a bit up higher. When I get a chance, I'm going to try to boost up the other settings and see if that helps.
 

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Phaed... did you notice any difference in your low end Tq with the SET removed?
dunno, haven't got it back yet. but, from what i hear, i'm not gonna have any problems with hp nor torque :p i'm drinkin the jr trackpack koolaid.
 

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JUtah said:
I would think the SET can actuate fast enough... BUT... who knows. :D

How is Aurora these days?? I grew up there.
There's about 4 inches of snow on the ground and it's 18 degrees as I type this :confused:

Not good for riding but it sure is purdy :D

I have a lot of "kin-folk" around the Ft. Smith-Alma area and a few around Little Rock-Hot Springs. I need to get back there and see them some time soon :bigthumbsup:

Heavy Snow Warning

/O.UPG.KBOU.SN.Y.0009.000000T0000Z- 061129T1900Z/ /O.NEW.KBOU.HS.W. 0002.061129T0449Z-061129T1900Z/ LARIMER COUNTY BELOW 6000 FEET/NORTHWEST WELD COUNTY- BOULDER AND JEFFERSON COUNTIES BELOW 6000 FEET/WEST BROOMFIELD COUNTY- NORTH DOUGLAS COUNTY BELOW 6000 FEET/DENVER/WEST ADAMS AND ARAPAHOE COUNTIES/EAST BROOMFIELD COUNTY- ELBERT/CENTRAL AND EAST DOUGLAS COUNTIES ABOVE 6000 FEET- INCLUDING... FORT COLLINS...HEREFORD...LOVELAND... NUNN...ARVADA... BOULDER...GOLDEN... LAKEWOOD...LONGMONT...AURORA... BRIGHTON... CITY OF DENVER...DENVER INTERNATIONAL AIRPORT...HIGHLANDS RANCH... LITTLETON...PARKER...CASTLE ROCK...ELBERT...FONDIS...KIOWA... LARKSPUR 949 PM MST TUE NOV 28 2006

...HEAVY SNOW WARNING IN EFFECT UNTIL 12 PM MST WEDNESDAY...

THE NATIONAL WEATHER SERVICE IN DENVER HAS ISSUED A HEAVY SNOW WARNING...

SNOW IS EXPECTED TONIGHT AND WEDNESDAY WITH TOTAL ACCUMULATIONS OF 5 TO 10 INCHES. SNOW WILL BE HEAVY AT TIMES WITH SNOWFALL RATES IN EXCESS OF ONE INCH PER HOUR.

A HEAVY SNOW WARNING MEANS SEVERE WINTER WEATHER CONDITIONS ARE EXPECTED OR OCCURRING. SIGNIFICANT AMOUNTS OF SNOW ARE FORECAST THAT WILL MAKE TRAVEL DANGEROUS. ONLY TRAVEL IN AN EMERGENCY. IF YOU MUST...KEEP AN EXTRA FLASHLIGHT...FOOD...AND WATER IN YOUR VEHICLE IN CASE OF AN EMERGENCY.
 

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Discussion Starter · #13 ·
When I bought my wifes C50 it was about 40 degrees with a 3.5 hour ride to get it home... Within an hour of the house it was snowing (Wasnt supposed to be).

Nothing is more exciting then riding a brand new bike at 28 Deg when it is snowing!  :eek:
We're supposed to get a couple of inches of snow tomorrow, but nothing like CO snow...

I miss snow and skiing! (I know everyone who has to shovel it is scratching their heads now)  :D
 

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I think like most exhaust valves it is to keep a linear power curve on tap with stock ECU mapping. some of the 4 cyl bikes have a more elaborate exhaust valve that changes the pipe from a 4-2-1 to a 4-1 with the exhaust valve so that it gives the best of both pipe designs at their designated rpm range. Yamaha has gone a step further on the new R1 sportbike and uses a variable intake system that gives two different intake tract lengths like stacks to better suit the powerband at different RPM's. what about this new 07' Zook 1000 that gives you a handlebar switch for fast, normal or wet riding by offering 3 different ign/fuel maps. thats pretty cool. :bigthumbsup:
 
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