Subject: GPR Exhaust DB Killer Rattle Fri Nov 08, 2024 9:24 pm
Long story short: 2016 GRiSO 1200SE repaired after accident. Second hand GPR exhaust acquired and added to bike as original exhaust is no longer available from MDL or any dealers... Love the new exhaust's look, but the DB killer rattles. Does anyone have any experience with the GPR exhaust and how to install the DB killer so it doesn't rattle and I get my mid range punch back.... I will get the bike remapped for this exhaust, but not unless I can get the DB killer in and rattle free... And no, I will not run it without the DB killer no matter how fruity it sounds, the performance is diminished without back pressure and my neighbours have guns.
Cheers BMR
Last edited by BMR on Sat Nov 09, 2024 7:33 am; edited 1 time in total
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beetle GRiSO Capo
Posts : 10198 Join date : 2013-09-30
Subject: Re: GPR Exhaust DB Killer Rattle Sat Nov 09, 2024 12:01 am
BMR wrote:
the performance is diminished without back pressure
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Pete Roper GRiSO Capo
Posts : 10704 Join date : 2013-05-29 Age : 67
Subject: Re: GPR Exhaust DB Killer Rattle Sat Nov 09, 2024 1:07 am
‘Back Pressure’ is not a thing. You’ll find it drives Mark and I to distraction. Mark more than me though.
BMR Carlotto
Posts : 28 Join date : 2022-07-19
Subject: Re: GPR Exhaust DB Killer Rattle Sat Nov 09, 2024 7:35 am
Pete Roper wrote:
‘Back Pressure’ is not a thing. You’ll find it drives Mark and I to distraction. Mark more than me though.
I stand corrected, Gentlemen. I have struck it off, just don't tell me the world is flat :-)
BMR Carlotto
Posts : 28 Join date : 2022-07-19
Subject: Re: GPR Exhaust DB Killer Rattle Sat Nov 09, 2024 7:39 am
BMR wrote:
Pete Roper wrote:
‘Back Pressure’ is not a thing. You’ll find it drives Mark and I to distraction. Mark more than me though.
I stand corrected, Gentlemen. I have struck it off, just don't tell me the world is flat :-)
The performance with Beetle's map on the stock exhaust was an amazing transformation. But with the GPR it has lost that torquey punch around 5k and up (running too lean?). Will mapping fix this or do I start looking for a second-hand stock pipe, as sound is great, but velocity is golden.
Cheers. BMR
beetle GRiSO Capo
Posts : 10198 Join date : 2013-09-30
Subject: Re: GPR Exhaust DB Killer Rattle Sat Nov 09, 2024 1:35 pm
The world is an oblate spheroid.
The reflected pressure waves with the GPR will be different than those with the stock exhaust, thus causing the difference in performance that you noted.
I cannot help you with the rattle, other than guessing that either the manner of affixing said dB killer is incorrect, or perhaps it's the wrong one for that pipe?
I do have maps for the GPR, so the performance issue can be fixed.
. [You must be registered and logged in to see this image.] . In GRiSO we trust! .
BMR Carlotto
Posts : 28 Join date : 2022-07-19
Subject: Re: GPR Exhaust DB Killer Rattle Sat Nov 09, 2024 3:47 pm
Perfect - I thought reflected pressure waves were only associated with 2 stroke expansion pipes on my old LC350 - you live and learn every day. Thanks Beetle. I will be downloading a GPR map soon. Cheers BMR.
beetle wrote:
The world is an oblate spheroid.
The reflected pressure waves with the GPR will be different than those with the stock exhaust, thus causing the difference in performance that you noted.
I cannot help you with the rattle, other than guessing that either the manner of affixing said dB killer is incorrect, or perhaps it's the wrong one for that pipe?
I do have maps for the GPR, so the performance issue can be fixed.