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Exhaust Servo

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Reach out to all BT tune users:

Can any of you contact BT with the question under which the exhaust flaps are actuated?
They are the ones whom no doubt have seen the codes and looked at changing or not.

Thanks for the video; question aswered for me.
 
Petrus said:
Happy that you are happy.

I do not know what the operating criteria for the flaps are.
They are a ´Bobby dodger´ for the EU noise emission tests for homologation.
This test involves idle, mid revs when stationary but also roll by test at various speeds incl. full throttle accelleration.
The CPU can tells the servos to actuate the flaps under ány of above and more conditions.
Although ´we´ assume when it actuates it can very well be that it only actuates with a lot of throttle between 50 and 70 km/h per example.
It is ONLY an invention to pass the EU noise test.

The tests also involve the stationary measurements to establish a sound level which can be verified during periodic inspections and at road side stops.
This dB level is included on the EU vehicle license registration documents and it is a bit higher than the value measured at homologation to compensate for potentially increased noises by use.
At inspection they will check a homologation number on the mufflers as well. If one decided to fit an after market one, the homologations document of the mufflers must be presented with the vehicle papers at inspection.

Anyway, I am unaware of when, under which circumstances, the flaps are actutated. Would lóve to know.
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Australia doesn’t have the strict emission laws that Europe has.
 
Petrus said:
BMW makes no OZ market model so still same as OEM bike exhaust flaps come
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Regardless off the country of origin, the Police generally will only bother you if any vehicle of any type is exceptionally loud or you act like a dick. Even vehicle inspectors are not ott if you are decent.
 
HUNTS said:
Regardless off the country of origin, the Police generally will only bother you if any vehicle of any type is exceptionally loud or you act like a dick. Even vehicle inspectors are not ott if you are decent.
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Great. Count your blessings.
In the EU it is @n@l and vehicle inspectors have OCD.
 
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So thought I'd add my observations here after disconnecting the electrical plugs from the unit that controls the exhaust plates (pic below to show what the plugs look like but they're in front of the REAR wheels - the actual exhaust valves are behind the front wheel).

I didn't want to do all the work to remove the actual valves or disconnect any cables so this was an easy option that could be easily reversed if I didn't like it.

The right side was easy to remove but the plug on the left side is facing up as I recall so it was more tricky. Nevertheless, I removed them both and put some tape over the ends to keep any debris from entering and went on about a 30 km ride.

I noticed that the sound went from being more characterful to being more "smooth". I did not like it as much and when I stopped to meet a buddy put the connectors back on and that's where they'll stay.

I'm suspecting that a partial opening of the valves causes pulses that give the exhaust tone more of braaap sound on throttle. I did not notice any performance differences.

Anyway, FYI for those that may be considering this ... I'm glad I didn't do all of the surgery that some have done.

Here's the pic from the easier right side:

1783434244091.png
 
Star-Lord said:
Reduced weight... Improvements are debatable.. the exhaust note sounds a little more throatier..
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I had the opposite effect, was not as throaty/rumbly to me but more smooth when I disconnected the electrical connectors ... clicked them back soon after and prefer it that way.
 
HUNTS said:
How does that improve the bike?
Not being mechanically minded (ok, it’s a lack of ability), how is this different from just have the exhaust valve disconnected?
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I don't think it improves the bike at all. Just a less subdued sound when rolling between 1,000 to 2,000 rpm.
By the same token, I don't think that the whole servo mechanism improves the bike in any way. So why have that.
 
emgarciax said:
I don't think it improves the bike at all. Just a less subdued sound when rolling between 1,000 to 2,000 rpm.
By the same token, I don't think that the whole servo mechanism improves the bike in any way. So why have that.
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It is ONLY a ´Bobby dodger´ mechanism to meet EU sound emission tests; specifically the roll by and accelerate. Removing will increase the sound under those conditions. If not audibly, it registers on the dB meter.
 
Probably responsible for the torque flat spot people report as well. Fwiw.... really improved my r9t.... not so much on the 18 (sound wise... but that was with the fish tails.... possibly a bit different with the varous exhausts).
 
The exhaust servo unit is an example of over-engineering.
Generally speaking though, I like BMW engineering.
When I shift into 1st after starting the engine, I hear a faint click. When I shift into first on my HD StreetGlide, the bike lurches forward with a loud thud, as if I just sheared a pin.
 
BER18 100 said:
The exhaust servo unit is an example of over-engineering.
Generally speaking though, I like BMW engineering.
When I shift into 1st after starting the engine, I hear a faint click. When I shift into first on my HD StreetGlide, the bike lurches forward with a loud thud, as if I just sheared a pin.
Click to expand...
You never had a NotSoModern (two stroke, hand shift) Vespa; Italian aircraft engineering.
 
Eventually got rid of a fault code identified using the HEX GS-911 (Fault code: Ox3A112)
Completely removed exhaust servo motors and connecting wires to the flapper valves & fitted a pair of Healtech eliminators to prevent warning lights.
Didn't even need the GS-911 to clear codes. They cleared themselves.
I realised it was likely the servo motors as I could not hear, or feel any noise from them when waking up the bike.
 
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