Lambda sensor - yes or no?

Mac Henderson

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I currently have a Remus with Y pipe on my 03 twin spark, and although I love the sound, it can get a little tiresome on long trips (especially for anybody following). Having read the various threads, the established wisdom suggests that replacing with the "Cat + Stubby" option is a sort of halfway house between the Remus and the standard system in terms of volume. The added bonus of 2 full size panniers is also attractive, so I think this could be the way to go, and a fairly cheap experiment as cats with the sensor are from £50 on ebay.
So, if I make the change, is it worth fitting the lambda sensor or just blanking off the mounting hole? Also, should I expect to see any significant drop in performance? When I bought the bike the seller said the Remus was "good for an extra 5bhp"; is this right or marketing hype/wishful thinking? It certainly sounds faster, so it must be true!
Any input/experience gratefully received.

Thanks,

Mac
 
Best to fit the sensor if you are fitting the cat.
 
Did the bike originally come with a cat? If it did then the ecu may not have been getting all the info it needs (ie to run mostly closed loop fuelling) without the lambda and the bike may have been operating in some sort of limp mode, or at least not at its best. If it was a non cat then you won't need the lambda as the bike will be set up to run open loop fuelling. From what I understand the best thing to do is as these bike run lean is to fit an af-xied if you have a lambda or temperature spoofer if no lambda.

If it runs fine without the lambda, maybe the best thing is to use the collector box off an 1100 or non cat 1150 (if such a thing exists) as this will probably knock something off the decibel level without having to plug the hole.
 
Ive got a spare cat/sensor cluttering up my junk store.
Yours if you want it,no charge, but you need to collect.
 
Colban said:
Ive got a spare cat/sensor cluttering up my junk store.
Yours if you want it,no charge, but you need to collect.
Click to expand...

Bottom line is if it’s got fuel injection it won’t work correctly without an Oxygen sensor.
 
Bottom line is if it’s got fuel injection it won’t work correctly without an Oxygen sensor.
Click to expand...

As I understand it, if the ecu was designed to run without a lambda (most UK 1100GSs for example) then that's what they do, just simple open loop fuelling only dependent on the map and the throttle postion. If it has (or should have) a lambda then the ecu will not be getting some of the information it needs to work properly in closed loop if it's been removed (eg it is not getting the 'feedback' from the lambda its expecting) and may adjust itself accordingly, which you can bet is to protect the engine, not give more power.

Some information here: http://www.bikeboy.org/open_closed_loop_efi.html

Was a cat still an option by 2003 in the UK, or were they fitted to all bikes by then?
 
ThreeDawg said:
As I understand it, if the ecu was designed to run without a lambda (most UK 1100GSs for example) then that's what they do, just simple open loop fuelling only dependent on the map and the throttle postion. If it has (or should have) a lambda then the ecu will not be getting some of the information it needs to work properly in closed loop if it's been removed (eg it is not getting the 'feedback' from the lambda its expecting) and may adjust itself accordingly, which you can bet is to protect the engine, not give more power.

Some information here: http://www.bikeboy.org/open_closed_loop_efi.html

Was a cat still an option by 2003 in the UK, or were they fitted to all bikes by then?
Click to expand...

My 2002 1150GSA had a CAT fitted.


Sent from Steve's fancy iPad using Tapatalk
 
Running the bike with a stubby fitted to the cat is only very marginally noisier than standard and apart from the odd fart on the overrun is virtually unnoticeable. In over twelve years of running with this configuration (lambda in situ) I have had no problems of any kind, including at mot time.
 
Aidan1150 said:
Running the bike with a stubby fitted to the cat is only very marginally noisier than standard and apart from the odd fart on the overrun is virtually unnoticeable. In over twelve years of running with this configuration (lambda in situ) I have had no problems of any kind, including at mot time.
Click to expand...
Ditto what Aidan said.
I found the bike pulls better from mid range and above but does run a bit on the lean/hot side. But otherwise I can't fault it and definitely recommend it
 
Many thanks for the replies, and to Colban for the kind offer.
I believe the bike originally had a cat, as its a 2003 model and Rugged Path's 2002 model has one. The original silencer came with the bike when I bought it (Sept. 2015), but no collector/cat.
Its been trouble free with the current system and no sensor, so I'm guessing the ECU has been fooled into thinking the sensor is still there via a jumper plug or similar, or has adapted/retuned itself (although I'm not sure how it would do that with no sensor to give feedback...).
Cat + stubby is looking like the way to go. Time to get into the shed and start looking for the redundant sensor plug. Any hints on where to route the sensor wiring, or will it all be blindingly and Germanically obvious once I fit the cat?
 
There are any number of reasons and situations why I would wish my GS to be a bit louder. If a stubby was all that it takes to achieve this purpose, why wouldn't BMW Motorrad acknowledge this somewhere on their FAQ page?
Has anyone run the stubby for 100K km plus with positive feedback and no engine or build issues? I am seriously considering the stage 10D chip from John G to address a bit more power at higher revolutions. Your thoughts please.
This seems to be an interesting on-going topic that fills many pages in many forums.
Cheers, R
 
Mac Henderson said:
I currently have a Remus with Y pipe on my 03 twin spark, and although I love the sound, it can get a little tiresome on long trips (especially for anybody following). Having read the various threads, the established wisdom suggests that replacing with the "Cat + Stubby" option is a sort of halfway house between the Remus and the standard system in terms of volume. The added bonus of 2 full size panniers is also attractive, so I think this could be the way to go, and a fairly cheap experiment as cats with the sensor are from £50 on ebay.
So, if I make the change, is it worth fitting the lambda sensor or just blanking off the mounting hole? Also, should I expect to see any significant drop in performance? When I bought the bike the seller said the Remus was "good for an extra 5bhp"; is this right or marketing hype/wishful thinking? It certainly sounds faster, so it must be true!
Any input/experience gratefully received.

Thanks,

Mac
Click to expand...

In my experience the performance 'enhancement' of the free-flowing exhaust is minimal, and wearing the engine in over time/distance releases more than having a y-piece and Remus. I tend to prefer the 'cat+stub' because it looks cleaner, makes the large pannier possible and makes rear-wheel removal far easier.
The cat (ime) does most of the 'silencing' work anyway, so the bike isn't that much louder than stock. (quieter than y-piece and remus).

Re the Lambda sensor - I'd refit it.

BTW - if anyone wants a stub, I have an old cat from which I cut one of the inlet pipes off to make my stub (it's exactly the right diameter), makes for a nice slash-cut stub. If you want to do the same with the other (slightly shorter) inlet pipe, let me know and we'll figure out someway of getting the thing to you. :) (I'm based in Woking).

 
Rhodee said:
There are any number of reasons and situations why I would wish my GS to be a bit louder. If a stubby was all that it takes to achieve this purpose, why wouldn't BMW Motorrad acknowledge this somewhere on their FAQ page?
Click to expand...

Why would they?? The bikes are built to a legal standard, even though the franchisees often allow (at their own discretion) bikes to be fitted on purchase with loud exhausts, that's a service to the customer from the franchisee and has nothing to do with BMW Motorrad themselves.

Rhodee said:
Has anyone run the stubby for 100K km plus with positive feedback and no engine or build issues?
Click to expand...

I ran my ~120K Rockster (no 3) with cat+stub for the majority of it's life, didn't seem to do it any harm. Running Rock4 now with the same setup (see photo in post above).

Rhodee said:
I am seriously considering the stage 10D chip from John G to address a bit more power at higher revolutions. Your thoughts please.
This seems to be an interesting on-going topic that fills many pages in many forums.
Cheers, R
Click to expand...

I'm considering something similar for next year on Rock4.
 
Riceburner said:
Why would they?? The bikes are built to a legal standard, even though the franchisees often allow (at their own discretion) bikes to be fitted on purchase with loud exhausts, that's a service to the customer from the franchisee and has nothing to do with BMW Motorrad themselves.



I ran my ~120K Rockster (no 3) with cat+stub for the majority of it's life, didn't seem to do it any harm. Running Rock4 now with the same setup (see photo in post above).



I'm considering something similar for next year on Rock4.
Click to expand...

He’s Canadian. They’re on a par with Americans for needless fiddling and stressing and obsessing over nothing.
 
Rhodee said:
Has anyone run the stubby for 100K km plus with positive feedback and no engine or build issues?
Click to expand...

I have run my 1150 for over 120K miles (about 195K km) with a stubby in Europe, the US and Asia without any issues at all.
 
I like the Remus, it makes a lovely, mellow burble behind me. i don't consider it to be offensive and I certainly don't get any trouble by it on long runs - and I often do 500 mile plus days in the summer. Running up to Hirstals, 1184 miles in one day, I wasn't fatigued by the exhaust note! Same going to Orkney for the weekend this year, 1874 miles from Thursday to Monday, take out Saturday and Sunday because they were the rally days and much alcohol was involved. No noise problem whatsoever. More northern softies. ;)
 
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