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Discussion Starter #1
Hi guys! Just replaced the CAT with Danmoto link pipe and I also have a short slip-on (SC Project) while keeping the stock headers. Engine runs fine except weird timing just at idle. Once I twist the throttle, is smooth as silk. Question: I'm worried of potential engine damage long term if I don't use a fuel/air manager like the PCV, although as it is I would rather keep the current setting. Anybody better informed on potential engine damage with this setup? Thanks for well-informed (not guessing) answers.
 

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Discussion Starter #3
I would never do that to an exhaust system so sorry I can't help you.
Could you kindly elaborate? The weight savings, louder engine rumble and freer-breathing acceleration makes it a worth modification in my view. Besides, many people do it, including replacing the entire exhaust system, with no drama that I can recall. The only concern is a lean mix down low may create some engine issue, or so I hear. Thanks for your views.
 

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friend of mine did the same on a new bike (not a BMW). Decat, new exhaust, no tune.

5-6 months later its in the shop sounding like a bucket of rusty bolts in the back of a pickup truck.

You're gonna spend a lot on a new zorst, spend the extra and get a tune as well. Its either cry now ($$), laugh later, or laugh now and cry later ($$$$)
 

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Discussion Starter #5
friend of mine did the same on a new bike (not a BMW). Decat, new exhaust, no tune.

5-6 months later its in the shop sounding like a bucket of rusty bolts in the back of a pickup truck.

You're gonna spend a lot on a new zorst, spend the extra and get a tune as well. Its either cry now ($$), laugh later, or laugh now and cry later ($$$$)
I see. Question: Would it be enough to get, say, a PCV and download the closest configuration map while skipping the dyno session? I am nowhere near a bike dyno shop. Thanks for the heads-up.
 

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I see. Question: Would it be enough to get, say, a PCV and download the closest configuration map while skipping the dyno session? I am nowhere near a bike dyno shop. Thanks for the heads-up.
I'm not sure about PC tunes to be honest, I'm sure someone else here knows more about it.

I would be looking at a handheld tune device with pre-loaded flashes. There's a few companies around that do this. Benefit is you can flash back to stock any time (like if taking it to the dealer if its still under warranty)
 

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Hi guys! Just replaced the CAT with Danmoto link pipe and I also have a short slip-on (SC Project) while keeping the stock headers. Engine runs fine except weird timing just at idle. Once I twist the throttle, is smooth as silk. Question: I'm worried of potential engine damage long term if I don't use a fuel/air manager like the PCV, although as it is I would rather keep the current setting. Anybody better informed on potential engine damage with this setup? Thanks for well-informed (not guessing) answers.
All these posts might be irrelevant. What year and model?
 

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I just talked to a couple of dealerships about K67 availability, and warranty the other day. BMW approves of having a full system, no flash/tune, as long o2 sensors are used on full exhaust to keep warranty.
 

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Discussion Starter #10
I just talked to a couple of dealerships about K67 availability, and warranty the other day. BMW approves of having a full system, no flash/tune, as long o2 sensors are used on full exhaust to keep warranty.
Mine still has the O2 sensors connected. In addition, it still has the butterfly valves on the original headers.
 

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Discussion Starter #12
I would recommend a power commander in this case and get yourself an appointment with a reputable tuner in your area. Where are you located?
There's only one non-reputable dyno shop out of town (I live in Panama City, Panama). My mechanic agrees with your take: Power Commander and a couple sessions on that dyno ... I was hoping to avoid this step, as I don't trust that shop, but now it seems inevitable. Thanks for the heads-up!
 

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It's aboot the money. Spend that cash on a PC and dyno time only to find out there's an unrepairable flat spot in the midrange. Better to go straight to a full system, even an inexpensive one, it will work so much better.
 

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Discussion Starter #16
Seat-of-the-pants tell me there are no flat spots in the RPM band so far. A flat spot is quite noticeable while riding ... I initially feared possible low RPM weakness due to thin mix, which did not happen racing the bike over straights and all sorts of slow and fast curves at speed. I may not be optimizing its potential, but runs great and the real concern is eventual engine damage, if that is the case. I mostly race it on roads not tracks. Of course, the full exhaust is better but it also conveys the same PC and tuning approach, with a setup cost much higher for the full exhaust. I also believe the German-engineered headers are quite competent. But I hear you, and will re-think your suggestion. Thanks!
 

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If you're worried about the bike, relax. Many others have gotten rid of the environmental restrictors with no damage occurring to the bike. leave the O2 sensors, leave the wires and valve for initial warm-up and free up the breathing by cutting off the cat. use the DanMoto pipe, it works. the bike will "learn" the new "flo". If that's not enough, send the ECU to Bren, then you'll have a fire-breather! Go for IT!
 

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Discussion Starter #18
If you're worried about the bike, relax. Many others have gotten rid of the environmental restrictors with no damage occurring to the bike. leave the O2 sensors, leave the wires and valve for initial warm-up and free up the breathing by cutting off the cat. use the DanMoto pipe, it works. the bike will "learn" the new "flo". If that's not enough, send the ECU to Bren, then you'll have a fire-breather! Go for IT!
Thanks so much for the encouragement. I have been hoping that was the case. I have already made those mods exactly as you suggest, and ridden the bike with no issues. I sincerely hope you are right. The money would be better spent in overhauling the front forks, with new oil and seals, as that oil is already 7 years old. Once done, measuring SAG and adjusting the suspension for my physical characteristics will ensure optimal front suspension along with complementary rear shock adjustment. That is my immediate next project combined with inverting the rear suspension's eccentric for more relaxed riding posture and better leaning leverage in curves. Thanks again!
 

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2012 BMW S1000RR, with around 8 K miles.
*edit* this is just my experience, if someone has factual scientific reason (other than what i stated) that it could damage the bike, please share.

not a BMW but just for reference ive done about 15k km on my zx10r with the same setup, straight through midpipe and shorty coke can sized exhaust (cheap local custom job, only $120 for the whole thing)... its wicked loud and pops and backfires and spits flames on decell (because the factory pair system still in place, too lazy to install block off plates until next time i need a filter change)... i ride it very hard most of the time... if something was going to happen i believe it would have already.

without a proper tune (closest shop for me is 2hrs away) the factory ECU and O2 do their best to adjust, and i think at most RPM they do a decent job thats why it feels smooth on throttle... idle and low throttle cruising can be a bit choppy due to the computer not being able to adjust itself enough in those ranges... mine idles perfectly after it warms up, but until its warm its a bit high... but low throttle cruising like through a parking lot where im just barely above idle in 1st gear its really choppy and surges... .a tune would fix this (and also gain a lot of power), maybe next month when i have time.

some people worry about the decell backfire causing damage, and yes it can damage your muffler packing... but i dont think it will hurt the engine because any explosion happening within the exhaust manifold is nowhere near as stressful as the explosions that happen inside the cylinder already during normal operation.

another concern is that if the engine is running rich or lean, you can definitely cause a problem... but as stated, the factory ECU should be able to adjust itself enough to avoid any issue there.

i think if we could look into the stories of anyone having an engine problem from a decatted exhaust you will likely find that there is an additional issue that contributed to the problem... clogged fuel injector, bad plug, ignition problem, etc

that being said, check your plugs... and when you can get a proper tune then do it, of course that is the best way to be safe.

when the K67 finally comes to thailand ill probably go with a short can again, but ill take a look at what options are available at the time... maybe a custom setup... its still another 4-6 months before first K67 will arrive here anyway, plenty of time for more options to pop up... i like the akra carbon can thats out now, but it will be crazy expensive here.

pic to show how short/minimal the exhaust is... its almost like having no muffler at all... sounds glorious at WOT >:)

 

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Discussion Starter #20 (Edited)
*edit* this is just my experience, if someone has factual scientific reason (other than what i stated) that it could damage the bike, please share.

not a BMW but just for reference ive done about 15k km on my zx10r with the same setup, straight through midpipe and shorty coke can sized exhaust (cheap local custom job, only $120 for the whole thing)... its wicked loud and pops and backfires and spits flames on decell (because the factory pair system still in place, too lazy to install block off plates until next time i need a filter change)... i ride it very hard most of the time... if something was going to happen i believe it would have already.

without a proper tune (closest shop for me is 2hrs away) the factory ECU and O2 do their best to adjust, and i think at most RPM they do a decent job thats why it feels smooth on throttle... idle and low throttle cruising can be a bit choppy due to the computer not being able to adjust itself enough in those ranges... mine idles perfectly after it warms up, but until its warm its a bit high... but low throttle cruising like through a parking lot where im just barely above idle in 1st gear its really choppy and surges... .a tune would fix this (and also gain a lot of power), maybe next month when i have time.

some people worry about the decell backfire causing damage, and yes it can damage your muffler packing... but i dont think it will hurt the engine because any explosion happening within the exhaust manifold is nowhere near as stressful as the explosions that happen inside the cylinder already during normal operation.

another concern is that if the engine is running rich or lean, you can definitely cause a problem... but as stated, the factory ECU should be able to adjust itself enough to avoid any issue there.

i think if we could look into the stories of anyone having an engine problem from a decatted exhaust you will likely find that there is an additional issue that contributed to the problem... clogged fuel injector, bad plug, ignition problem, etc

that being said, check your plugs... and when you can get a proper tune then do it, of course that is the best way to be safe.

when the K67 finally comes to thailand ill probably go with a short can again, but ill take a look at what options are available at the time... maybe a custom setup... its still another 4-6 months before first K67 will arrive here anyway, plenty of time for more options to pop up... i like the akra carbon can thats out now, but it will be crazy expensive here.

pic to show how short/minimal the exhaust is... its almost like having no muffler at all... sounds glorious at WOT >:)
Nice bike! I wonder how do we upload images in this forum? A rich mix burns in the heat of the muffler making those pops you mentioned, nothing to worry about, I would agree. Lean mix is another whole issue and that can be damaging, but as you said, chances are the ECU adjusts to that before any damage can occur. My bike is running better than ever except for the irregular idle. I have not checked the plugs personally, but the bike just went through a whole due maintenance schedule at the BMW distributor, so I believe they checked those. My seat-of-the -pants test was done in the twisties, through all kinds of slow and fast curves. The idea being if there was any fueling hesitation it would interfere with the bike's handling during the apex-passing, low throttle phase. It didn't. In fact, it runs better than before as it breathes better and has more power out of the curves. I also ride hard and only on weekends due to lesser traffic and because I need to go to the twisties, which are about 1.5 hrs away in a beautiful natural setting. Getting there and out is all highway stuff where, now and then, I also press hard. My end can is also quite short and noisy :). I'll go about the tuning later probably, but it is not a priority as the only shop available is not experienced and I fear exposing the bike to wrong treatment. Thanks for your thoughts!

I'm offering the URL of my bike's photos in the following post.
 
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