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Re: Exhaust Flow Control Valve (Twin Cam 2013)
Posted: Wed Dec 19, 2018 1:11 pm
by David.
Recently purchased some Plusgas,
http://www.plusgas.co.uk/about-plusgas/
Plusgas quote,
"It breaks the grip of rust, scale, carbon, paint and gum.", thought the carbon bit might be appropriate for the exhaust system.
Re: Exhaust Flow Control Valve (Twin Cam 2013)
Posted: Wed Dec 19, 2018 3:42 pm
by Beagle
David. wrote:
Recently purchased some Plusgas,
http://www.plusgas.co.uk/about-plusgas/
Plusgas quote,
"It breaks the grip of rust, scale, carbon, paint and gum.", thought the carbon bit might be appropriate for the exhaust system.
By gum that brings back memories. Used this in the 60’s as a freeing agent. ( like wd40) It will burn off quickly though.
Re: Exhaust Flow Control Valve (Twin Cam 2013)
Posted: Wed Dec 19, 2018 9:49 pm
by LAF
Well I just put a Akrapovic header on my 17 GS. I used a Servo Buddy
https://www.skutr.net/servo-eliminators/ and it eliminates any issue with the servo. Everything is gone.
I ran my GS-911 on it and it passed the two Servo Tests so the Servo Buddy works for sure.
Re: Exhaust Flow Control Valve (Twin Cam 2013)
Posted: Tue Sep 03, 2019 8:11 am
by David.
Whilst at Hilltop, it was reported that the Exhaust flap servomotor fault code is currently present again. Their advice was not to remove the flap, it helps with exhaust back pressure at low engine speeds.
Having just paid £320 for re-mapping, I'm happy to follow this recommendation.
The bike is booked in tomorrow (Wednesday) at Cooper Sunderland for them to have a look at it. My objective is to hopefully have the flap replaced under warranty.
The flap is £320, plus labour for fitting, my warranty excess is £100.
I took the silencer off and checked the flap, is it indeed not cycling from full open to fully closed & back, only going partially closed.
Looking back at this thread has provided valuable evidence that the fault existed 12 months ago.
Re: Exhaust Flow Control Valve (Twin Cam 2013)
Posted: Tue Sep 03, 2019 9:27 am
by Rick B
Im on my 2nd set of headers due to the flap seizing up,all done under the warranty.
Re: Exhaust Flow Control Valve (Twin Cam 2013)
Posted: Tue Sep 03, 2019 2:08 pm
by David.
Fortunately for BMW the exhaust flap on a TC is not part of the headers.
Re: Exhaust Flow Control Valve (Twin Cam 2013)
Posted: Wed Sep 04, 2019 7:51 pm
by simbo
David. wrote:
Whilst at Hilltop, it was reported that the Exhaust flap servomotor fault code is currently present again. Their advice was not to remove the flap, it helps with exhaust back pressure at low engine speeds.
Having just paid £320 for re-mapping, I'm happy to follow this recommendation.
The bike is booked in tomorrow (Wednesday) at Cooper Sunderland for them to have a look at it. My objective is to hopefully have the flap replaced under warranty.
The flap is £320, plus labour for fitting, my warranty excess is £100.
I took the silencer off and checked the flap, is it indeed not cycling from full open to fully closed & back, only going partially closed.
Looking back at this thread has provided valuable evidence that the fault existed 12 months ago.
What was the outcome at the dealers David?
Re: Exhaust Flow Control Valve (Twin Cam 2013)
Posted: Wed Sep 04, 2019 7:58 pm
by David.
simbo wrote:What was the outcome at the dealers David?
Having spent hours washing & polishing the bike, based on the weather forecast, decided to re-schedule for Tuesday next week.
Re: Exhaust Flow Control Valve (Twin Cam 2013)
Posted: Thu Sep 05, 2019 11:03 am
by LAF
The flap does NOTHING for performance in any of the PRM range.
It is there strictly for noise reduction. if you start you bike with the muffler off you can see and watch the flap at a few throttle positions. It never closes more then 2/3rds of the way and is full on open at 3500 RPM.
And as to the TC there was a slip on pipe made to eliminate that flap pipe that was a inexpensive way to get rid of it. Now built into the headers makes it a very expensive replacement.
Me I just put a set of Akropovic SS headers on and called it a day.
Re: Exhaust Flow Control Valve (Twin Cam 2013)
Posted: Thu Sep 05, 2019 12:01 pm
by David.
KS Motor give the following tech-info for exhaust gas flaps on motorcycles,
"Reduces the flow area in the low to medium engine speed range for increased dynamic pressure. This increases the cylinder charging and therefore also the torque.
Releasing the full tube cross-section in the upper engine speed range for maximum performance and sporty sound."
Re: Exhaust Flow Control Valve (Twin Cam 2013)
Posted: Thu Sep 05, 2019 3:09 pm
by simbo
David. wrote:
KS Motor give the following tech-info for exhaust gas flaps on motorcycles,
"Reduces the flow area in the low to medium engine speed range for increased dynamic pressure. This increases the cylinder charging and therefore also the torque.
Releasing the full tube cross-section in the upper engine speed range for maximum performance and sporty sound."
9 out of 10 cats prefer whiskers cat food too
Re: Exhaust Flow Control Valve (Twin Cam 2013)
Posted: Thu Sep 05, 2019 3:59 pm
by David.
Here's what was written in BMW Motorcycle Magazine about the similar flap on the HP2 Sport (where this first appeared):
"This constantly adjusts the internal diameter of the exhaust system to suit engine revs and ensures good low to mid-range performance for a linear power output all the way to the rev limiter."
Re: Exhaust Flow Control Valve (Twin Cam 2013)
Posted: Thu Sep 05, 2019 4:33 pm
by simbo
David. wrote:
Here's what was written in BMW Motorcycle Magazine about the similar flap on the HP2 Sport (where this first appeared):
"This constantly adjusts the internal diameter of the exhaust system to suit engine revs and ensures good low to mid-range performance for a linear power output all the way to the rev limiter."
The HP2 probably has a free flowing exhaust to allow for more top end performance, hence the need for a valve to close it up a bit to give it some bottom end torque. The RT not so much, it's for noise regulations and nothing else.
Re: Exhaust Flow Control Valve (Twin Cam 2013)
Posted: Sun Sep 08, 2019 8:52 am
by David.
This video of an R1200R
https://www.youtube.com/watch?v=kECJwihAW6w shows the exhaust flap going from full open, to full closed & back to full open when the ignition is switched on.
Re: Exhaust Flow Control Valve (Twin Cam 2013)
Posted: Tue Sep 10, 2019 8:16 am
by David.
David. wrote:Decided to re-schedule for Tuesday next week.
Off to Cooper BMW Sunderland this morning, will report back later.
