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Surging Cured

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Screw it, I'm going to go you all one better.

I'm not only going to remove the secondary butterflies, I am also going to remove the primary ones as well and just let the sucker run at full throttle all the time and just slip the clutch a lot. :rofl:

Surging, I don't have no stinking surging. :-P :lol2:
 
Is there a good explanation of exactly what the secondary butterflys do? I'm with a few others on this thread where as I would most likely never do this, but I am curious why they are there in the first place.

Is this removal process allowing more fuel? If so, how does the stock O2 sensing circuit work as in does it cut the fuel back?

Just thinking.......:shrug:
 
El Bandito said:
Screw it, I'm going to go you all one better.

I'm not only going to remove the secondary butterflies, I am also going to remove the primary ones as well and just let the sucker run at full throttle all the time and just slip the clutch a lot. :rofl:

Surging, I don't have no stinking surging. :-P :lol2:
Click to expand...

:rofl:
 
PhilS said:
Is there a good explanation of exactly what the secondary butterflys do? I'm with a few others on this thread where as I would most likely never do this, but I am curious why they are there in the first place.

Is this removal process allowing more fuel? If so, how does the stock O2 sensing circuit work as in does it cut the fuel back?

Just thinking.......:shrug:
Click to expand...

Secondary butterflies are to smooth the throttle transition. They are implemented since 85-90%(out of the blue guesstimate. No figure to back that up) of riders are not trying to have throttle snatchy bikes.

In general they cut back 5 +- a few ponies in the effort to make the throttle on transition smooth. I have heard of 8hp gains on the fazers and zixxers with the removal of secondaries and if rworm's dynos show 12hp gain with only secondary fly removal then that's what we can say for the bandito.

It wouldn't suprise me though because this bike has a ton of oomph that zuki has toned down to appease the saddlebag crowd.:lol2:
 
I'm more on the not sure whats going on in this thread but if removing these secondary butterflies adds 12 give or take ponnies plus a little more torque it just might be worth getting someone who does know to help me do this job. I'm always game for a little more power thats doesn't kill me on $.
 
My only con is I am a see it to believe it kind of guy so I need to see before and after dyno runs before i will accept a 12hp/no bs.:mrgreen: Heck, I'll take just an after dyno plot but I will not take someones word on the internet however capable I or others think they may be.

Also I still don't understand why anyone would go through the motions of removing secondary flies, removing the airbox, and not adding a tuning module. I'm still missing something here. A carb'd bike I could understand but EFI I do not.

Rworm are you just against getting a tuning module, waiting to get one or just trying to see what the stock ECU can do?

Also I think it would be appropriate to show a dyno plot before a bunch of people go drilling their secondary flies out expecting 10+- a few ponies. Of course each to their own I presume.
 
red757 said:
Also I think it would be appropriate to show a dyno plot before a bunch of people go drilling their secondary flies out expecting 10+- a few ponies. Of course each to their own I presume.
Click to expand...

I should point out again that I did not remove the secondaries in order to gain more power - I did it in order to gain more control over how the engine runs. This it achieves extremely well but no dyno chart is going to demonstrate the improvement because dynos can't measure rideability.

I will post a chart once I've had the bike set up properly but this will just be an 'after' - I don't have the time or finances to make multiple dyno runs to analyse incremental changes.

Riding around on the bike last night it became obvious that the secondaries were there, as someone else suggested, to 'damp' throttle input - now, if you grab a handful the bike just launches itself instantly while before it would accelerate smoothly with, presumably, the secondaries preventing anything too extreme from happening (by opening more gradually). I'm an experienced rider - I am quite capable of telling the bike how hard I want it to accelerate without some electronics trying to save me from myself and calm things down. But Suzuki presumably decided to tone down the performance for marketing reasons.

The secondaries probably have a.....er.....secondary purpose - to cut down on induction noise (the difference is noticeable) and the surging around 2,500rpm may well be as a result of them staying more closed than they should be at whatever engine speed they do the drive-by noise test at. They would also be able to affect emissions - cut down the air flow and you can cut the amount of fuel you need at whatever speeds the emissions testing is done at. Of course the way the bike runs will suffer, but we've all experienced that......

It has become obvious that there were many situations in which the secondaries were interfering with the instructions from my right wrist and I am happy to see them gone - the bike is transformed and it's not even set up properly yet. But there are people riding about on 1250 Bandits who are happy with the way their bike runs and they would be best advised to leave them well alone. I reported back on this mod because I felt that it made a good bike considerably better - it's not compulsory for everyone (or anyone) to follow suit!

Some of us, though, have an urge to fiddle and this is another easy and effective means of fiddling :lol2:
 
red757 said:
My only con is I am a see it to believe it kind of guy so I need to see before and after dyno runs before i will accept a 12hp/no bs.:mrgreen: Heck, I'll take just an after dyno plot but I will not take someones word on the internet however capable I or others think they may be.

Also I still don't understand why anyone would go through the motions of removing secondary flies, removing the airbox, and not adding a tuning module. I'm still missing something here. A carb'd bike I could understand but EFI I do not.

Rworm are you just against getting a tuning module, waiting to get one or just trying to see what the stock ECU can do?

Also I think it would be appropriate to show a dyno plot before a bunch of people go drilling their secondary flies out expecting 10+- a few ponies. Of course each to their own I presume.
Click to expand...
Hey i was just sharing my experiences/a liar by no means if thats
what you are gettin at;-)
My bike was 96HP 1st dyno run
107.88 2nd dyno run
rworm
 
gunzip said:
Sproggy is your airbox stock ? :eat:
Click to expand...

No. I currently have the following engine mods (pretty much the standard list):

Airbox drilled (as per Holeshot recommendations) and snorkel removed
K&N filter
PAIR pipe blocked
Secondary butterflies removed
Yoshi Oval Cone muffler
PC111 and O2 bypass
ATRE

Arrow headers to be fitted next week.

I wouldn't imagine that having a K&N filter and drilled airbox would change the effect of removing the secondary butterflies - i.e. you'd see the same improvement on an otherwise stock bike. But not having tried that I can't say for sure - up to someone else to find out. But probably the sort of person who's going to go to the trouble of removing the secondaries won't be willing to leave everything else stock :trust:
 
Checking the manual, makes me wonder if you could simply unplug the STVA?

st.jpg
 
I went through the fault codes/conditions and descriptions of the system in the manual to see whether I could over-ride the secondary system or maybe have a switch somewhere that could open the secondaries fully without affecting the sensor signal. But anything I could think of to do would throw up a fault code, put the FI light on and (by implication) affect the way the bike runs. There's a phrase somewhere in the manual that says something like 'when the FI light comes on to signify a fault condition the bike may seem to be running normally but it's not quite".

Anyway, now I've done it and ridden the bike I can't think of any reason why I'd want to put the secondaries back in - that shaft can turn away to its heart's content, all the sensors will be happy, but it won't be interfering with my enjoyment of the bike.
 
Yeah, no doubt you're all correct. It was a spur of the moment thought, but the chance of unhooking that motor without affecting other things, was doubtful once I had time to think about it.

Too bad, I'd really like to make it reversible, for when I sell. And, I have the SEP warranty till 2011, and would hate to screw that up for the next owner. I'm sure they could use that as a reason to deny warranty coverage for an engine failure.

I wonder what the ECU would do if you unhooked the FI light completely? It couldn't flash the light at ya' to TELL you it's unhooked!!.:mrgreen:

Maybe a mallet comes out of the guage area, and smacks ya' in the head?:rofl:

yes, that was just a joke!
 
I can't help but wonder if Dale is watching this thread as he completes the testing and tuning of the new Bandit header....
 
sproggy said:
I went through the fault codes/conditions and descriptions of the system in the manual to see whether I could over-ride the secondary system or maybe have a switch somewhere that could open the secondaries fully without affecting the sensor signal. But anything I could think of to do would throw up a fault code, put the FI light on and (by implication) affect the way the bike runs. There's a phrase somewhere in the manual that says something like 'when the FI light comes on to signify a fault condition the bike may seem to be running normally but it's not quite".

Anyway, now I've done it and ridden the bike I can't think of any reason why I'd want to put the secondaries back in - that shaft can turn away to its heart's content, all the sensors will be happy, but it won't be interfering with my enjoyment of the bike.
Click to expand...

Hey Sproggy,

The STP sensor output signal,to the ECU,varies from .6v closed, to 4.5v fully open. I'm wondering if you pulled the sensor, set it for .6v, lock it in position, and leave it off....if, that wouldn't send a constant signal to open the flies?
 
dmerc said:
The STP sensor output signal,to the ECU,varies from .6v closed, to 4.5v fully open. I'm wondering if you pulled the sensor, set it for .6v, lock it in position, and leave it off....if, that wouldn't send a constant signal to open the flies?
Click to expand...

It might do, but if the ECU thinks the secondaries are shut (which it always will if you feed the STP wire 0.6v) surely it will restrict fuel flow accordingly?
 
sproggy said:
It might do, but if the ECU thinks the secondaries are shut (which it always will if you feed the STP wire 0.6v) surely it will restrict fuel flow accordingly?
Click to expand...


Hopefully, it fuels only by the primaries.....I'll pull the sensor and try turning it manually while it's running. I s'pose it'll throw a fault/light regardless.

EDIT: I tried it this morning, before the heat sets in! The flies cycle as part of the FI test when the key is turned on, which would make it impossible to set it at a constant value. PLUS, even if it's already running, when I pull the STP sensor off, it instantly kicks the light. No idea how it "knows" I'm doing it. I made sure I had a grounded jumper wire for the metal area where the screw goes, just in case it was loss of ground....tried slowly turning the sensor manually, but could not get the light out.

I guess I'll live with the secondaries for now.....:lol2:
 
So even if you pull the motor that operates the secondaries off it still lights the FI light? I thought if you could take the servo motor off and somehow prop the butterflies open that you would be ok and not have to take the throttle bodies off, and I mean leaving the motor hooked up so it could still go through it cycle. I know leaving the butterflies in wouldnt be as free flowing as taking them out but it would be reversible and a lot less hassle.
 
yamadavidson said:
So even if you pull the motor that operates the secondaries off it still lights the FI light? I thought if you could take the servo motor off and somehow prop the butterflies open that you would be ok and not have to take the throttle bodies off, and I mean leaving the motor hooked up so it could still go through it cycle. I know leaving the butterflies in wouldnt be as free flowing as taking them out but it would be reversible and a lot less hassle.
Click to expand...

I haven't had a close look at the SVTA motor. Even if you could just pull it, (which would be great!!) you'd still have the STP sensor crying foul.

I can't figure how it KNEW the STP sensor was pulled out! The light would come on instantly! Put it back in, goes out (after restart) Nothing was unhooked.....

That ECU is way too smart for a dumb ol' farm-raised boy like me!!:giveup:

I even checked out some Gixxer and 'Busa boards, thinking maybe they had done it.....nuthin'!

I'd just pull the TB's and remove the flies, if I KNEW I could get the screws out, but it doesn't sound likely.
 
dmerc said:
I haven't had a close look at the SVTA motor. Even if you could just pull it, (which would be great!!) you'd still have the STP sensor crying foul.

I can't figure how it KNEW the STP sensor was pulled out! The light would come on instantly! Put it back in, goes out (after restart) Nothing was unhooked.....

That ECU is way too smart for a dumb ol' farm-raised boy like me!!:giveup:

I even checked out some Gixxer and 'Busa boards, thinking maybe they had done it.....nuthin'!

I'd just pull the TB's and remove the flies, if I KNEW I could get the screws out, but it doesn't sound likely.
Click to expand...
You could try a handheld rheostat:-P
rworm
Which hand tho
 
Someone asked (ages ago) for a picture of the TBs without the secondary butterflies. As they had to come out again today to adjust the TPS here's the picture:

IMG_0370.jpg
 
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