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Discussion Starter #1
I finally screwed up my courage to hook up my GS-911 to my new to me second hand, well out of warranty, 2015 K1300S. There were a few known bulb failure faults. All faults cleared except an Exhaust Flap Servo Motor fault 10313. Do I play BMW mechanic, buy and install a new one? Or is there a better, cheaper (those things cost nearly $260.00) more elegant fix? The bike runs fine, but does pop on a 4th to 5th shift assist shift. it has an Akropovic exhaust. I’m wondering if the previous owner didn’t disconnect it?
 

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Did you start the bike? if not id does show error when reading the codes, same on my, the servo works fine but i get a code with only ign on, probably due to the fact that it does not actuate when engine off so computer does not get a signal from it. Check under servicefunctions and i think you can make it move for functioncheck without engine on.

Exhaustpop with an acra and qs, if you only get 1 pop, you're not opening the throttle enough...it should pop and spit flames on all shifts, no danger. The flap is just there to reduce noise and is more closed the less throttle is open, an adjustable DB-killer so to speak. If you disconnect the wire to the flap it stays in full open position, disconnect the servo and it stays in closed and bike would not run on higher rpm's.
 

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Discussion Starter #3
Thanks for the input. I’ll recheck it. I’m still learning my way around the GS-911.

A POP and flames with each shift? N E A T!!
 

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Discussion Starter #4
Okay, I hooked up the gs-911, fired up “Death Wish” and lo and behold, the 10313 error code is still there Bike runs beautifully, but a non-clearing error code is still troubling. Now what? Where is the servo located? It appears to be in the bowels of the motorcycle, of course.
 

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I’m still on the learning curve. I wasn’t aware of a service mode. I guess I need to dig through the GS-911 some more. How do I tell if the valve is working when I use the throttle? Can this be done without removing the can? I don’t think it would run too well at full throttle with the valve closed. Frankly, I think the valve is a pain that could become a real problem in the future. I believe that it will default to open if I just disconnect the Bowden cable? If I elect to do that, how do I remove the plastic splash guards?

You’ve been a big help with this. Thank you for your time, patience and knowledge.
 

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If it were closed the bike would not run at high rpm. The cover is screwed on if my memory is not totally off.

Disconnect the cable andut flips to fully open yes. Some do just that and tuck the cable away, servo works but flap is always open.

Never heard if an actual problem with this part.
 

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Discussion Starter #8
Thanks, again. This part reminds me of a side stand switch. It’s not necessary for the bike to function, and it is just something that could be a nuisance down the road. I’m beginning to think I’m making a mountain out of a mole hill, though.
 

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Thanks, again. This part reminds me of a side stand switch. It’s not necessary for the bike to function, and it is just something that could be a nuisance down the road. I’m beginning to think I’m making a mountain out of a mole hill, though.
Think you are, even if the servo fails when out riding, just unhook the cable or cut it off and the flap opens.
 

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The exhaust flapper doesn't do anything except provide back pressure to heat up the catalytic converter faster. The only issue I've seen is that after some time the flapper can get stuck closed or partially closed. I have a 2011 R1200GSA that has the flapper and most people simply remove the flapper and install a small piece of stainless tubing you can get easily from a parts store. Then just tape up the plug and you're done. If you hook up your GS-911 you'll see the active code but it won't trigger a fault at the dash and the bike will be otherwise unaffected.
 

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Motorcyclist magazine did a test. They found a LOSS of 3-5 lb-ft between of torque 2750 and 4500 rpm with the exhaust valve removed. I does help with low end noise but many bmw's are loud, take a 2015 S1000R for example. With more complete burn cycle at low rpms, air polution is reduced while mpg slightly helped.
Here is a post from adv rider:
"So I'm taking an engine maintenance course and the instructor said something very cool the other day. There is this thing called "valve overlap", a moment in the engine cycle where the intake and exhaust valves are both open simultaneously. When this happens, the intake fuel is prevented from going out the exhaust port by the reverb of the ignition sound bouncing back into the combustion chamber -the sound wave (back pressure?) keeps the fuel in the chamber."

There is a valve flap that controls this. It's "closed" to reflect back the sound at low RPM, where the time for the fuel to reach the exhaust port is less than the time for the piston to complete a cycle. At high RPMs, the piston is moving quick enough to close the exhaust valve before the fuel reaches the port so the flap is open. Even in my on line tech sheet of improvements to the K13 series, the flapper is mentioned to help with low end performance.

Thinking about it, I see no tech reason for this to be used to heat up the cat faster. Then why would it be functional when the bike is warmed up. The computer could easily open it all the way when the bike is up to temp. When used with secondary chamber it can be used to tune various functions such as sound. Many vehicles use this system.
 

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That's interesting @Beech. I've also seen test data (on an older GSA) that showed virtually no difference in power or torque with or without the flapper installed. That data showed that the valve served no function after the engine reached full operating temp. It was suggested that this might be used to heat up the CAT and help reduce cold start emission, a requirements of strict EU emissions standards.

On an ADV bike, it's just one more thing to go wrong when your 100 miles from a paved road so I err on the side of simplicity. In fairness, my R1200GSA is from 2011 (DOHC oil cooled). I wonder if in subsequent years BMW added more functionality to the valve that is more differential on the K1300S. Take the S1000RR for example. In the track racing community, most everyone removes these valves in favor of a full exhaust but then they're all running custom dyno tunes as well. Is it possible to re-tune the K1300S ECU or is a Power Commander required for this? I've shied away from a power commander on my K12S just because the interface is terrible, with wiring all over the place in very tight spaces. The bike makes plenty of power without it, but I do wonder about how much it might smooth out the power/torque curve and also potentially improve fuel economy with more accurate fueling. Beyond the messy install, buying a PC and then paying for a custom tune would run nearly $1000 so that's another reason to avoid it for me. I think I'd rather upgrade to a nice Wilbers suspension first.

In any case, appreciate all your insights on this.
 

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I agree with you about the wiring for some of the control additions. The K12 series has poor city manners. Its home is on the highway. I once borrowed my friends to chase down some parts while out of state (I crashed my K13) and I was astounded how nasty it was in town. My original K12S bike did not seem as bad as his. I have read in some forums that the ecu can be re flashed but have not paid attention because my bike runs well. Took awhile to get here though. New air box and computer updates (OEM). As you say newer bikes have different updates. Recently I sent my injectors to Mr. Injector for cleaning. Wow, so much smoother. My K13S has a warm up cycle of running at about 1600 rpm for a minute or less before it drops back to about 1200. BMW handed over the K12 to Recardo Engineering in the UK for a work over. (https://ricardo.com/) Wanted it to run better. That is where the K13 came from. I have a 20 page document in the files talking about all the changes. I'm sure there are instances of failure of the flap works, but I have not heard of any in my circle. I have on line though. A once a year or so inspection of the cables would be warranted if one is worried. As you say when an aftermarket exhaust system is installed you have no flap. But the bike will run like crap if you do not change the engine control chip program.
 

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Are you thinking Dr. Injector in Kirkland?? Love Tony, he does great work. It's always amazing to me how much difference a cleaning and flow bench testing to ensure fuel flow uniformity makes. You've probably seen my posts all over this forum about re-setting ignition advance / fuel burn values stored in the ECM. When I did think on my K12S it had a massive impact on the bike's city drivability. The bike had been a major handful, with abrupt on/off throttle and big power hits. After I had the values reset and let the computer relearn them for a few miles, the bike completely changed. It ran super smooth and was much easier to ride on city streets. On/off throttle was far more manageable and power delivery is now quite smooth. It's weird, the bike actually feels lighter and smaller, just way more manageable on all fronts.

So question for you?? I know there are a bunch of technical differences between the K12S and K13S, but what's the real difference in terms of how they both ride?? My K12S is really wonderful to ride, is the K13S worth spending up for?? I've considered upgrading but haven't been able to find a K13S somewhere I can ride to make a direct comparison.
 

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As far as handling and comfort ( say comfort as my K bike is comfortable for me), I don't think there is much difference. If your bike runs well I don't see the need except things start to get old. I ran across a K13 2011 or so with 8K miles at a car dealer in Tacoma. Almost it. Might still be there. Good time to make offers. The K13 engine is an improvement. I got 112,000 miles out of my clutch, more to go when I opened it up but refreshed it anyway.
Mr. injector, Idaho
https://www.mrinjector.us/
 

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As far as handling and comfort ( say comfort as my K bike is comfortable for me), I don't think there is much difference. If your bike runs well I don't see the need except things start to get old. I ran across a K13 2011 or so with 8K miles at a car dealer in Tacoma. Almost it. Might still be there. Good time to make offers. The K13 engine is an improvement. I got 112,000 miles out of my clutch, more to go when I opened it up but refreshed it anyway.
Mr. injector, Idaho
https://www.mrinjector.us/
I think I saw the same one, black on black?? It was a 2015 with 9800 miles. I was going to buy it but someone beat me to it.
 

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I gots opinions.

AFAIK the exhaust flapper is not INTENDED to be an adjustable dB device, though it may seem so.

And it isn't INTENDED to heat up the cat sooner - that is the function of the ECU and warm-up mixture control by the ECU. Backpressure don't have a single thing to do with cataverter heating. Correct me based on plausible, reasonable information from informed sources, and if I'm shown wrong I'll apologize to the group.

The flapper is there to enable a "tunable" exhaust, the same as a dual-length intake plenum. Different engine speeds benefit from different length intake and exhaust paths. The flapper's function has to do with how the acoustic pressure wave created by inlet and outlet valves travels along the inlet and exhaust paths.

But it's IMHO a common misconception that it's there only to modify exhaust sound. It does, but that's a byproduct, not the intent, of its operation.

SEE ALSO, the K1300GT doesn't have this valve and runs a few less HP, I'm thinking the valve is a benefit, not an imposition. Can/will it fail? As much as anything. If one is afraid of malfuction do you also remove your EFI and replace it with a hoggin' big Quadrajet? Take off the ABS? Heck why not remove the muffler altogether, it's only gonna rot out someday.
 

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I think we all agree with your points @Honolulu, but perhaps with the caveat that the system you describe has evolved over time and is likely more sophisticated (and impactful) on newer bikes than on older bikes. Early versions of this system appear to have a less dramatic impact on engine performance but with some liability.

And yes, early versions of EFI systems we're sometimes ripped out and replaced with a carburetors. The same can be said of early versions of ABS (1st gen BMW ABS was terrible). Technology is our friend but maturity matters too and some 1st gen systems caused more problems than they solved for consumers.
 

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Discussion Starter #19
I’ve owned a K1200R and K1200R Sport I sold them because of potential clutch and gearbox issues. I now have a K1300S. The K1300S is civilized in town. My K1200 bikes were a handful in town and nearly impossible with the 10mph speed limit in my neighborhood. I installed an AFX-IED on them. Even then, 10 mph was not much fun. Otherwise, aside from reliability of clutches and transmissions, the two are quite close in comfort, handling and engine performance.
 
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