Has anyone disabled exhaust valve on stock XB12 exaust?

[ElMonkey]

I bought a used '04 XB12S last summer and am in the process of figuring out what I want to do about the exhaust. The threads and tips on the website are incredibly helpful - especially since the supply of aftermarket Buell stuff seems to be getting slim with the shut-down of Buell (the only new aftermarket exhaust I can find for sale is a Jardine). It looks like the aftermarket exhaust moders are still in business, for now, but I've got the equipment and probably the skill to attempt a DIY mod. In my research I came across something I wanted to ping the Buell DIY community on…

What I hate most about my Buell is the almost unsafe behavior when rolling the throttle on from a stop as my bike wants to be rev'd to about 3G's to launch smoothly. Anything between idle and 3G's is a crap shoot - which is scary when going into a turn from a stop or pulling into an intersection. I don’t think this is just my bike because it the same thing happened to me on an ’09 XB12S that I took for a demo ride last spring…

While researching exhaust options I came across some incredibly helpful dyno's provided by American Sports Bike website (http://www.americansportbike.com/). What has my attention is the dyno charts for the stock XB12, race XB12 and Special Ops XB12. All three of these consistently show that there is essentially no tractable power generated by the bike below 2600-2800 RPM, which correlates with my seat of the pants exeperience. All other exhausts tested show tractable power from about 2200 RPM. The main difference between these two behaviors is the exhaust valve - the stock, race and Special Ops exhausts all use the valve where the others don't.

So here's my question - has anyone run their stock XB12 exhaust with the exhaust valve disconnected? If so, how did it affect the behavior? In my understanding of what's going on with that thing I actually think the valve would want to be actuated open to reduce the flow resistance, so if just disconnected and left closed it may have made the performance worse... When it warms up I’ll give it a shot on my bike but just thought I’d check with the community first.

A 400 RPM difference in power band wouldn't mean much to an R6, but given the low rev range of our bikes, it's not trivial - plus it's at the lowest rev's, which is not the greatest place for missing power. If it weren’t for this behavior I’d absolutely love this bike – right now I just like it a lot [smirk].

Thanks!

PS - I tried searching for this topic before posting - man could this website use a Google search engine.

 

[Stevenc150]

the stock, race and Special Ops exhausts all use the valve where the others don't.

The Buell Race exhuast doesn't have an exhaust valve.

What you're wanting to try would be easily tested by just unplugging the servo on top of the inside airbox and taking a run. You're check engine light will come on but it'll run fine. Just plug it back in when you return and the CEL should go back off.

You'll get better at the slow-speed manuevering as you become more accustomed to it. Like you said, it's no ricer. The breather-reroute, if it's not already done, may help some with lower RPM stumbling also. NGK Iridium spark plugs (DCPR9EIX) are great plugs if some of the stumbles is coming from plug fouling.

I tried searching for this topic before posting - man could this website use a Google search engine.

On Google type: site:buellxb.com [whatever you're searching for]

It does a search of this site using the Google search engine. Very effective. [up]

Edit: ...and Welcome to the Forum

 

[theoctopus]

My 09 Ss has a breather reroute, FAST intake, GB exhaust, modified ECM, and servo emulator, and there's no real surging at low RPMs. Most people say that the breather reroute is the best option, though it did not really provide me with noticeable differences. A good exhaust and a good tune are your best bet.

 

[ElMonkey]

Thanks for the quick tips. I'm just starting to get a handle on the breadth of topics I need to consider and the breather routing is something I intend to look into. I fiddled with this a little last fall by taking the tank cover off (not exactly, I propped it up) to offer a more direct unrestricted air intake and riding around my neighborhood. No the safest thing to do, but it was a dry clear day. It did seem to run better, but it was a pretty sketchy setup. I'll dig into those related posts and see what I can make of it.

Thanks for the Goggle search tip. I think that almost any Buell related word will show up in almost any thread if it's long enough so it's a little hard to get what you're looking for. I'll give it a shot.

 

[kbaddict]

If you just pop the gas with the clutch engaged and then roll onto the throttle as you let out the clutch out you won't ever have a problem. I just put my new race ecm on last night and it seem to help elimate the problem.

 

[Macbuell]

I have an 04 and have no problems 1k-3k range. Was not much of a problem, and then I did breather re-route and it was all gone. My baby is smooth all over.

You will figure it out if it is new to you, if not, look into possible causes because I don't think it is normally that bad.

 

[nativeXb12Rbuell]

maybe I dont understand your question fully but,.. as said before The Buell Race exhuast doesn't have an exhaust valve as it is basicly a straight through into a chamber then exits out which gives a different back presure and faster flow for the exhaust gases, for many different reasons( remember the stock xb12 muffler has mutiple chambers and pipes for this purpose) . the purpose of the exhaust valve on the xb12 muffler is to give the engine optimal back pressure during different rpms and differnent throttle positions for the what the ECM is programed for .by letting the gases flow through it faster or longer time building up presssure depending on if the vavle is open or closed...I.E stock is basicly for epa regulations(amount of sound) and best MPG,& and best HP &torque , also why the ECM is a Learning ECM(to a certain amount).the D&D and SpecOps only have a exhaust valve if built from xb12 muffler and of course the ones built from the xb9 muffler dont have an exhaust valve.

this is what the BUELL service manual says about the Exhaust vavle on the xb 12 muffler, and how it works...
the ECM monitors engine speed & Throttle postion while alternating flow paths between the chambers to adjust BackPressure optimizing TORQUE & HORSEPOWER for the riding condition.
For Example:
1. at low RPM with a wide open throttle, the valve is opened to reduce back pressure so the engine can gain RPM quickly. The exhaust enters the muffler & flows through the open valve into the chamber C( the front chamber) then exits.(through the exit pipe).(see Yellow arrow flow path)
2. in the mid-range, the valve is closed to increase acceleration Torque. The exhaust flows through pipe to chamber A(the rear chamber), around to the pipe going through chamber B(the middle chamber with the pipes)and then through Chamber C and exits (through exit pipe).).(see RED arrow flow path)

3. At HIGH RPM, the valve opens again to maximize HORSEPOWER. The exhaust enters the muffler & flows through the OPEN valve into chamber C and then exits (through exit pipe).).(see Yellow arrow flow path)


the D&D and/or SpecOps basicly only have one or two chambers & an exit pipe (see some of the pics in other posts of the inside of those mufflers )if they retained the valve if built from a xb12 muffler.

if you disconnect the valve to stay closed on a stock XB12 with Stock muffler you will not recieve the benifits of it building RPM faster at LOW or HIGH RPM like in examples 1 & 3 above, WHEN IT REALY NEEDS IT THE MOST . you will lose that TORQUE & HORSEPOWER at low & high RPM .like when at higher speeds and when coming out of a corner or off the line from a stop or from a slowing down going into a speed up fast.

 

[ElMonkey]

NativeXB - Great detail. Is all of that info in the service manual? I was under the wrong impression that the valve was closed at low RPM and then opened at high RPM and am surprised it's actuated at two different RPMs – interesting... As I mentioned in my first post , I was thinking the valve should be disconnected and rigged in some way so that it would be open to lower the flow resistance at low RPMs. I thought this could be why the low RPM performance was different in exhausts that do and don’t have the valve, but if the valve is actually already open at low RPMs then something else must be causing this difference in the dynos…

 

[nativeXb12Rbuell]

yes thats all from the service manual. the service manuals are worth the money to buy one to have on hand while working on your bike, and if the server is up and running you can download a pdf of one on the link at the top of the page, but i suggest buying the service manual in book form to have for easier reading and acess when working on your bike.

 

[kiwilee]

Yes Hi from New Zealand.
I did this to my 08 Ully and it made a hell of a difference!!
I unhooked it at the exhaust and wired it open.
Sounds better, deeper and throaty not obnoxious.
and best of all smooths out the lower end.
I do lots of dirt roads and tracks over here and the bogging off the start was getting dangerous around cliffs and rocks so did this and the breather and air box mods and works a treat.
Tie it back for a little while and see if it makes a difference if you havnt already.
Cheers from NZ.

 

[ElMonkey]

@kiwilee: A couple of questions:

1) Did you do all of those changes at once? From what I've read the breather mod should have the biggest impact. I'd be really curious to know if there was any performance change with just the valve mod without the airbox/breather mods...

2) Besides the breather mod, what airbox mod(s) did you make?

3) Did you do any ECMSpy work or stick with your original map after making these changes?

Thanks for the info!

 

[kalifornia]

the exhaust isnt causing the problem, I've run my muffler fully closed to fully opened and everywhere in between with no felt effect on performance, just a decibel difference. on my 08 bolt the valve doesnt move, until (presummably) at wot

 

[kalifornia]

i'de say its either an intake leak or bad fuel delivery

 

[kiwilee]

sorry for the later reply ELMonkey.
I did each change a week apart.
I did not notice a huge difference in HP
but it definately smoothed everything out and just sounds heaps better.
The air box mod I noticed the most difference, and I used a hole saw and put three large holes in left hand side and carved some away fro the front to let more air through front.
I have not remapped and dont feel very confident as Im crap with computers!
But is running nice anyway (apart from snapped belt) cheers kiwilee

 

[XB4ME]

2009 xb12ss stock ECM. I disconnected valve actuator motor and ran the bike while pulling the cable in and out at constant rpm's and under acceleration, and noticed 0.0 difference in power. The noise increased when opened vs. closed though. I left the valve closed since I like the quiet sleeper sound (man I'm getting old). I performed a breather mod /catch can, and that did make all the difference when pulling away from a stop. It smoothed out the acceleration and now pulls as it should. I highly recommend the breather mod and don't even bother with the exhaust. BTW I did remove the exhaust valve motor and installed emulator because I am going to do an intake airbox mod shortly.

 

[Catmostfeared]

how do I unplug the exhaust and turn it off on ecmspy so the check engine light doesn't come on

 

[UMDterp13]

Find the 2 wires and complete the circuit

 

[Catmostfeared]

Have you done this cause that doesn't work