Secondary Butterflies removal review

Dozerdriver

Registered
After reading a thread on here I decided to remove the secondary flies on my Gen II. The removal goes as follows: Take off seat... Take out the tank hold down bolts and prop up tank ( I use a stick to make it higher ). Then take the airbox lid off and set it aside ( phillips screws ). Now you can get to the flies from here. What I did was to close the flies with my finger and work on the other side away from where I was holding. Two phillips screws on each plate is all you remove to get the plate out, I highly suggest a magnetic screwdriver. If you happen to drop a screw the other throttle body plates will keep it from going into the motor as long as you don't twist the throttle. Now after the four plates are out just put it back together.

My review of the performace is.... it does feel like the throttle is more crisp. I only rode about 25 miles so far so I will update this. I have tried a TRE and this mod feels about the same as that. I don't have a TRE anymore so not sure if this adds anything on top of one. I have no idea if the A/F is still ok but the bike does run fine with no flat spots or issues. I did have the bike running to watch the flies and they were closed even when I thottled it up some ( not sure what RPM they open ). When you get to them they are open but if you start the bike they close... not sure if it was due to the bike being on cold start? Anyways if anyone else wants to add to this ... please do.

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I started the thread a couple months ago. It works. I haven't dyno'd or ran at the track, but the seat of the pants feel is there.
The secondaries are in there to regulate airflow. For emissions, and the A,B,C mode, it also allows the power to come on smoother.
The difference in 1st and 2nd is obvious, the Busa now easily wheelies up like a 1000, which is the reason I took mine out.
This also doesn't lean out the engine, after almost a thousand miles without them, no problems and the plugs look fine.
For any who try this. In 1st gear, cruise along about 35mph, gas it, tach up to about 6 or 8 grand, let off, rpm's are falling, snap the gas. The Busa will power up into a wheelie.
Now remove the secondaries and repeat. It'll loop you now if you let it:laugh:
 
I started the thread a couple months ago. It works. I haven't dyno'd or ran at the track, but the seat of the pants feel is there.
The secondaries are in there to regulate airflow. For emissions, and the A,B,C mode, it also allows the power to come on smoother.
The difference in 1st and 2nd is obvious, the Busa now easily wheelies up like a 1000, which is the reason I took mine out.
This also doesn't lean out the engine, after almost a thousand miles without them, no problems and the plugs look fine.
For any who try this. In 1st gear, cruise along about 35mph, gas it, tach up to about 6 or 8 grand, let off, rpm's are falling, snap the gas. The Busa will power up into a wheelie.
Now remove the secondaries and repeat. It'll loop you now if you let it:laugh:

Mine was wheelie happy before and now seems even more crispy on the throttle. I figure it is a simple thing to do and reverse if I didn't like it. I didn't know how to add the original post you started. Go ahead and add the link if you want. :beerchug:
 
Mine was wheelie happy before and now seems even more crispy on the throttle. I figure it is a simple thing to do and reverse if I didn't like it. I didn't know how to add the original post you started. Go ahead and add the link if you want. :beerchug:

No, I don't care about that. I was just answering the question, and stating that I had done it to add credibility to my response.:thumbsup:
 
I asked the same question to Brock and put it to Brocks forum and got a resounding NO do not take them off on a Gen II (GenI and ZX yes?!?) - only thing is I asked "why" several times and never got an answer except Brock said it upsets his mapings for the PCV and his CT pipes so thats about all I can add - would love to actually get a technical answer though all I have ever seen is the above "seat of the pants" comments
 
Well I just got back from some more testing ( seat of the pants ):whistle: It is snappier... not a huge amount but noticable on mine. I will compare it to the Ivans TRE I borrowed and tried out. Pretty much feels exactly the same way... I wonder if the 5th gear map that the TRE uses has these flies open more to create the same feel as with them out. This would be in my opinion a better way to get the extra throttle response without using a 5th gear map all the time. I hope someone who knows the answers will chime in. I am curious when the flies open all the way ( what rpm ) and what gears. Thanks, Dozer.
 
From Brock's:

"**IMPORTANT**



2. Removal of the Secondary Throttle Plates IS NOT RECOMMENDED on the New Busa and the maps included ARE NOT intended for use with the plates removed. The 2008 Busa is as close to factory RACE BIKE as you can get...the secondary plates are used to smooth the power NOT restrict power as occurs with other bikes (like the ZX-14). At this point, we only see them functioning with the mode switch and low cruising speeds for emission purposes which are eliminated with the use of the power commander, our mapping, and jumper plug. "



Sounds like they could be removed, Brock's map's just aren't tuned specific for it, though. If the Power Commander disables them, then they're just slabs of metal sitting in the intakes? Maybe they still have some benefit. I'd like to hear more detailed input as well.
 
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If you have time put it on the hpc dyno. To see if it made any different?
Well I just got back from some more testing ( seat of the pants ):whistle: It is snappier... not a huge amount but noticable on mine. I will compare it to the Ivans TRE I borrowed and tried out. Pretty much feels exactly the same way... I wonder if the 5th gear map that the TRE uses has these flies open more to create the same feel as with them out. This would be in my opinion a better way to get the extra throttle response without using a 5th gear map all the time. I hope someone who knows the answers will chime in. I am curious when the flies open all the way ( what rpm ) and what gears. Thanks, Dozer.
 
Well you can set the stp with the ec editor. They are set at 100 at 800 rpm. Dont Know the ansewer but there is still a lot of air restriction with those STP plates and rods. In pro stock even the screws are rounded off and polished.
 
They are there to smooth the throttle action out,
Removing a restriction can not hurt the power output...
I removed mine the 1st 100 miles,
Just my 2 cents
Mike
 
They are there to smooth the throttle action out,
Removing a restriction can not hurt the power output...
I removed mine the 1st 100 miles,
Just my 2 cents
Mike

peak hp no, bottom end or mid range possibly could degrade
 
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Cool info. So I guess there is a difference on a stock bike with no tunes then?

I think imma try this! :laugh:
 
Cool info. So I guess there is a difference on a stock bike with no tunes then?

I think imma try this! :laugh:

Yes, there is a difference. My 08 has the stock tune. There is a noticeable difference in low/mid power in 1st, 2nd, and a little in 3rd. It isn't a big hp gain, but the bike lifts the front much easier. I had no problem wheelieing stock, but this makes it much easier to do, which is why I did it.
I was also suprised to see that it DOES accelerate much faster on the big end. I assumed with no tune surely at some point it would stumble, not so. With nothing restricting airflow, the needle pegs much sooner.
The bike feels the same throughout all gears and rpms, it doesn't seem to have lost anything anywhere. But I cannot say that for sure as the bike has never been dyno'd.
I originally posted this as a wheelie mod. One of the reasons for the secondaries is to smooth out the power delivery. The Busa is in the sport touring class anyway, it wasn't meant to be wheelie happy.
I'm not qualified to say, but I would tend to think the Busa would benefit throughout the entire rpm range with them gone...with a proper tune, to ensure peak performance. Even though again I've had no problems with them out and no tune.
As I said in my original post, I was skeptical that this would show any noticeable gain at all, and may even hurt performance...but this is not the case for everyday street riding.
If your bike has modifications and has been tuned and you take them out, that's another story, it may or may not help. It may make dragracing launches harder, and it will lift the front coming hard out of corners. I drag knees and had to adjust my brain to when the front was gonna lift now.
AGAIN, I like it better for street riding, and wheelies. I'm not here to claim HP numbers or 1/4 mile times. Regardless of modifications to any FI bike, most bolt ons don't need a dyno tune, but it is the only way to get the best performance out of the bike. :beerchug:
 
Does anyone know how much these flies open and what rpm.. I might put them back in and see. I want to try different gears and watch them. If someone is thinking of doing this maybe they will check this out. I am still thinking a TRE opens these more in the lower gears.
 
lol, you guys......

I have no idea why you would want a "snappier" busa. As it sets with a full pipe and PC-V if you crack mine open in 1st, 2nd, and at times 3rd you are reaching for the sky and I am 245 pounds.

If you like stunting or wheeling, maybe that is your ticket, but a busa with 2 wheels on the ground will outrun one with only the back tire all day long.
 
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