Secondary Butterflies removal review

[Busa1166]

I will be your huckleberry , going to do this mod when I put in a new air filter, if I like it, then I'll do the king too, hell what's there to lose by trying something new

horsepower if your butt dyno is a little off and you don't do a before and after on a dyno which isn't worth the money for the mod

 

[bradbusa]

so, i'm in the middle of taking the STP off just for kicks.. and one of the screws wont budge.. yep i stripped it. going to take a dremel to it so i can fit a flat head screwdriver just to get it off

wanted to see if anyone who has removed their secondary throttle plates still has the screws that held them in, and wouldn't mind selling me about 4 or 5 of them

 

[Dozerdriver]

The stock screws suck...very soft. You have to apply lots of pressure on them with a perfect fit phillips.

 

[BusaDudeBrazil]

Brad, we are all waiting for your feedback on the bike feel!

 

[bradbusa]

i was able to get 7 out of 8 screws out with mostly no issues. one decided it wasnt budging at all and is currently still in place. of the remaining 7 only 3 were slightly harder than the rest.

 

[sixpack577]

i was able to get 7 out of 8 screws out with mostly no issues. one decided it wasnt budging at all and is currently still in place. of the remaining 7 only 3 were slightly harder than the rest.

Pushing down hard and twisting the screwdriver while tapping it with a hammer makes them break loose very easy.

 

[Dozerdriver]

Pushing down hard and twisting the screwdriver while tapping it with a hammer makes them break loose very easy.

But once you mess up the head it's difficult.

 

[Blckbrd]

buddy pulling his out of his 09 zx14 had the same problem. he heated up the head of a phillips screwdriver till it was glowing & then held it to the heads of the butterfly screws to loosen the lock-tite or whatever the kawi guys put on them.

When I pulled them out of the Busa, no problems ... not tight at all.

I wonder .... could u use a narrow wood chisel to bite into the soft screw head & then press firmly & back it out? Better than trying to tap it, no?

 

[fadiizzaldin]

would setting the ECU Editor STP map to 100% all the way have the same effect,,,, hell i'll try it as well if so.... nothing to loose

 

[sixpack577]

But once you mess up the head it's difficult.

Yeah, I know. Had 1 on my friends ZX10 that wouldn't budge and the head stripped. Used this Craftsman bit and it came right out.

 

[BusaDudeBrazil]

would setting the ECU Editor STP map to 100% all the way have the same effect,,,, hell i'll try it as well if so.... nothing to loose

I wonder if that would work the same way, because even though they could be 100% opened, they are still physically attached making an effect on the airflow from the airbox into the throttle bodies.

It is very likely that you would notice a difference, nonetheless.

 

[sixpack577]

I wonder if that would work the same way, because even though they could be 100% opened, they are still physically attached making an effect on the airflow from the airbox into the throttle bodies.

It is very likely that you would notice a difference, nonetheless.

Smith says they will only open to 94%. If you physically open them by hand, you will see that they don't open to 90degrees. There is a noticeable angle on them, and they will still be directing air as long as they are in there.
Whether or not it makes a difference remains to be seen.
Someone will have to do several before and after dyno runs to put this to rest.

 

[bradbusa]

ok i'm back. i was able to find some very close replacement screws from the local ace hardware store.
i got the last screw out by taking a grinding wheel to the head of the screw and then using a flathead screwdriver to get it out.

took the bike for a test drive and immediately noticed a difference. it felt like the bike takes longer to rev and it didnt pull as hard until it got into the upper rpm range.. like after 8k. i didnt like the way it ran. i'm going to go ahead and conclude by saying on a bone stock bike with no other mods or software adjustments i think the engineers knew best. maybe with a full exhaust and air/fuel/timing adjustments this could help but i still feel the bike would suffer in lower rpm because it doesnt need that much volume of air.
i put them back in and the bike pulls so much harder now. 2nd gear almost lifts the front wheel, whereas without the plates it was nowhere near getting light up front.
whatever gains may be noticed in upper rpm range i think are offset by what is lost in the lower/midrange areas.

i was thinking about why the stps only shows a reading of 94% and i think it's so that the ecu can tell if there's a problem or not. kind of like an o2 sensor or maf sensor.. there's a range that it knows it's supposed to be in and if it goes above or below that, the system throws a check engine light or other fault code in the ecu. it has to have some kind of buffer so it knows when either the motor for the STP is broken or the sensor has gone out of range. just my thoughts..

 

[2wicked]

Quicker throttle response with them out, and more peak power, also no loss of low end torque or hp without them, not even sure where someone would get that notion?

The STPs open up differently in each gear, and actually do limit power, anyone who tells you different is uninformed, do a 2nd gear dyno pull, then a 3rd then a 4th, the plates open differently in each of these gears, dependant on engine rpm and primary throttle position. 4th, 5th and 6th share the same basic mapping for throttle plate opening. 1st, 2nd and 3rd are a lot lazier in the opening. Therefore is makes the bike more controlable in the lower gears. Remove the plates, adjust the tune and the bike will definitely wake up.

Richard

 

[sixpack577]

I take advantage of the low rpm slugishness to lift the front to where I want it. By the time it's up, I have full power to use however I like. I agree that stock performance depending on your riding style can be limited, and that with proper exhaust and tune, it would be better without them.
My daily driving is hard driving, I'm using the extra umph having them out gives. As opposed to smooth power delivery, with them gone, it's sluggish, and then full power. Kinda like a 4 barrell opening
So it's preffernce, unless properly tuned without them.

 

[2wicked]

, with them gone, it's sluggish, and then full power. Kinda like a 4 barrell opening
So it's preffernce, unless properly tuned without them.

Turn your throttle slower and smoother with them out and it will preform exactly the same as with them in,

Richard

 

[sixpack577]

Turn your throttle slower and smoother with them out and it will preform exactly the same as with them in,

Richard

Slow and smooth Man I ride the this thing as hard as I can, and as far as can on one wheel. What is slow and smooth????
I truly belive they are there for driveability for the masses, and tuned right with ECU Editor, the Busa benefits greatly from them gone.

 

[2wicked]

Slow and smooth Man I ride the this thing as hard as I can, and as far as can on one wheel. What is slow and smooth????
I truly belive they are there for driveability for the masses, and tuned right with ECU Editor, the Busa benefits greatly from them gone.

You are exactly right, because by simply removing them, the ECU is still fueling for the throttle position it believes it is delivering, but tune the bike with the plates removed, and also copy the 4th gear STP mapping into 2nd and 3rd and it will really wake the busa up in the lower gears, but, it will make the throttle respond a lot quiker and make it a lot more aggressive, that may not be great for everyone,

Richard

 

[sixpack577]

You are exactly right, because by simply removing them, the ECU is still fueling for the throttle position it believes it is delivering, but tune the bike with the plates removed, and also copy the 4th gear STP mapping into 2nd and 3rd and it will really wake the busa up in the lower gears, but, it will make the throttle respond a lot quiker and make it a lot more aggressive, that may not be great for everyone,

Richard

It'll be great for me as soon as the cash allows In the meantime I'll keep em out.

 

[BusaDudeBrazil]

I never changed fuel map after removing them and loved the difference it made.

I think that your bike may be suffering from being too lean on low end now that there is just too much air.

The secondary throttle plates are not there to optimize performance, they are there to limit and not to increase.

Do you know why the Gen 1 had no STP´s? Because it had an ignition timing retarder on the first gears to emulate the STP effect - it could be easily tweaked by a device that fooled the gear position sensor, the famous TRE. It does not work on Gen II Busas.

I think we all can come to the following conclusion, after Brad´s report:

More air flow from down low means the POSSIBILITY for more power to be made - however if it results in a lean or rich mixture, it will result in less performance.

Kind like a situation where one introduces forced induction with high pressure, but the stock injectors cannot cope with so much fuel needs and the end result is unoptimal power because of a too poor mixture.

With that said, I am surprised Brad did not report that even with less power, the throttle response (resolution in low rpm) difference is amazing. I still think that the throttle response difference alone is worth the mod, even if it made slightly less power (not the case with mine, guessing mine did not result being lean on low rpms after STP removal).