Rush Slip-ons decel popping
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2nd Gear
Joined: May 2011
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From: Somereset County, NJ
Rush Slip-ons decel popping
I know there are a ton of posts on this issue but I just got an answer from Rush that mayt be helpful to others. I bought and installed 1.75" baloney cut Rush slip ons for my brand new 2011 Fat Boy. Install was pretty easy except for the muffler support fasteners which are just hard to access but doable with some patience and banged up knuckles. First run out I got some annoying popping on decel and when disengaging the clutch.
I emailed Rush tech support and they came right back with this...
"Decel popping with the 1.75 baffles is most commonly caused by an exhaust leak. RUSH Exhaust is manufactured using 16-gauge steel, which is much thicker than stock and requires 65 ft.lb. of torque. To check for an exhaust leak, here is an east method. Start the bike and while it is idling, light a wooden match and blow it out. Immediately place it close to the connection of the muffler and the head pipe. If the smoke sucks inside the exhaust, you have a leak. It is best to do this in a garage where there is not any wind. You may also find it easier to use a cigar, cigarette, incense stick, etc."
Since the softail service manual calls for 38-43 ft-lbs on the muffler clamps, I was way undertightened.
Hope this helps
I emailed Rush tech support and they came right back with this...
"Decel popping with the 1.75 baffles is most commonly caused by an exhaust leak. RUSH Exhaust is manufactured using 16-gauge steel, which is much thicker than stock and requires 65 ft.lb. of torque. To check for an exhaust leak, here is an east method. Start the bike and while it is idling, light a wooden match and blow it out. Immediately place it close to the connection of the muffler and the head pipe. If the smoke sucks inside the exhaust, you have a leak. It is best to do this in a garage where there is not any wind. You may also find it easier to use a cigar, cigarette, incense stick, etc."
Since the softail service manual calls for 38-43 ft-lbs on the muffler clamps, I was way undertightened.
Hope this helps
Banned
Joined: Feb 2010
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From: P.R.O.K.
I know there are a ton of posts on this issue but I just got an answer from Rush that mayt be helpful to others. I bought and installed 1.75" baloney cut Rush slip ons for my brand new 2011 Fat Boy. Install was pretty easy except for the muffler support fasteners which are just hard to access but doable with some patience and banged up knuckles. First run out I got some annoying popping on decel and when disengaging the clutch.
I emailed Rush tech support and they came right back with this...
"Decel popping with the 1.75 baffles is most commonly caused by an exhaust leak. RUSH Exhaust is manufactured using 16-gauge steel, which is much thicker than stock and requires 65 ft.lb. of torque. To check for an exhaust leak, here is an east method. Start the bike and while it is idling, light a wooden match and blow it out. Immediately place it close to the connection of the muffler and the head pipe. If the smoke sucks inside the exhaust, you have a leak. It is best to do this in a garage where there is not any wind. You may also find it easier to use a cigar, cigarette, incense stick, etc."
Since the softail service manual calls for 38-43 ft-lbs on the muffler clamps, I was way undertightened.
Hope this helps
I emailed Rush tech support and they came right back with this...
"Decel popping with the 1.75 baffles is most commonly caused by an exhaust leak. RUSH Exhaust is manufactured using 16-gauge steel, which is much thicker than stock and requires 65 ft.lb. of torque. To check for an exhaust leak, here is an east method. Start the bike and while it is idling, light a wooden match and blow it out. Immediately place it close to the connection of the muffler and the head pipe. If the smoke sucks inside the exhaust, you have a leak. It is best to do this in a garage where there is not any wind. You may also find it easier to use a cigar, cigarette, incense stick, etc."
Since the softail service manual calls for 38-43 ft-lbs on the muffler clamps, I was way undertightened.
Hope this helps
I have a slight decel popping with my Rush slip-ons (1.75). I torqued the correct 43 ft-lbs. I'll try cranking them down to 65.
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Joined: Oct 2009
Posts: 682
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From: In the World
I doubt exhaust leak the issue...but then I am a know-it-all.
MOCO OEM ECU set lean to begin with to comply with EPA...Rush muffs just make mixture even leaner. Lean mixture will cause pops on decel. Also...factory muffs have integral cats and an equivalent baff of about 1.25 in. The cats get hot and restrict exhaust flow...plus they quiet down noise.
You can either have HD dealer download a map...if they have something for your muffs...or install a SERT and HD dealer with dyno can tune out pops.
MOCO OEM ECU set lean to begin with to comply with EPA...Rush muffs just make mixture even leaner. Lean mixture will cause pops on decel. Also...factory muffs have integral cats and an equivalent baff of about 1.25 in. The cats get hot and restrict exhaust flow...plus they quiet down noise.
You can either have HD dealer download a map...if they have something for your muffs...or install a SERT and HD dealer with dyno can tune out pops.
Road Master
Joined: Feb 2011
Posts: 784
Likes: 10
From: SE Pennsylvania
A lean mixture doesn't cause popping on deceleration, but unburned fuel coming from the engine and mixing with more air coming up through the exhaust will by acting a little like an after-burner. If anything, popping on deceleration indicates a slightly rich mixture. I can see how an exhaust leak may cause some popping, but, even if all leaks were sealed off, popping can still occur if the air/fuel mix isn't correct. Bringing in more air on the front end may reduce or eliminate popping by burning excess fuel (making it leaner) before reaching the headers.
But, what do I know....I'm just a banjo playin' inbred!
But, what do I know....I'm just a banjo playin' inbred!
Last edited by Jaburg1; Jun 7, 2011 at 02:40 PM.
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Joined: Apr 2011
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From: Northern NJ
My Rush slip-ons with 1.75 popped on decel. Got the PC 5 from Fuel Moto,
popping went away. Changed throttle % at idle from 3 to 0, popping came back slightly. Oh well...
popping went away. Changed throttle % at idle from 3 to 0, popping came back slightly. Oh well...
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Joined: May 2007
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From: 40 miles Northeast of Indy..
Had my Rush for 4yrs now and when new I had dealer install them at the 1k service with the SE /AC, SERT and dyno.
Ended up that the wrench installed the clamps to far forward on both pipes. Lots of decell popping
Back then the Rush tech said on the 2'' U can look into the mufflers from the rear end of the pipes while shinning a light around the outside of the clamp area,,,, if U can see any light, U've got leaks..
On mine we could see light at 6 of the eight slots where the clamps go.
They pulled the muffs and re-installed them with new clamps and got it right the second time.
Ended up that the wrench installed the clamps to far forward on both pipes. Lots of decell popping
Back then the Rush tech said on the 2'' U can look into the mufflers from the rear end of the pipes while shinning a light around the outside of the clamp area,,,, if U can see any light, U've got leaks..
On mine we could see light at 6 of the eight slots where the clamps go.
They pulled the muffs and re-installed them with new clamps and got it right the second time.
Last edited by oct1949; Jun 7, 2011 at 04:25 PM.
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Joined: Oct 2009
Posts: 682
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From: In the World
A lean mixture doesn't cause popping on deceleration, but unburned fuel coming from the engine and mixing with more air coming up through the exhaust will by acting a little like an after-burner. If anything, popping on deceleration indicates a slightly rich mixture. I can see how an exhaust leak may cause some popping, but, even if all leaks were sealed off, popping can still occur if the air/fuel mix isn't correct. Bringing in more air on the front end may reduce or eliminate popping by burning excess fuel (making it leaner) before reaching the headers.
But, what do I know....I'm just a banjo playin' inbred!
But, what do I know....I'm just a banjo playin' inbred!
From my paltry experience .. the paper bag rattle pop is a lean mixture issue and the LOUD POP can be a rich mixture issue ... oh my head hurts ... I really think timing is a big issue too ...
But what do I know ... I'm just a retired old phart. I finally cured my 2.0 in baff Rush POP by closing injectors from point I noticed POP to point where it no longer occurred by tuning my Tmax in Basic Settings ..... min and max POP positions .. I sort of like the paper bag rattle and did not tune it out... but its not doing it as much anymore maybe autotune sorted it out .. or I just don't notice it as much ...
There is a pretty good Utube video that aims to get rid of both afterfire and backfire ... here it is ...