Silencer question - can these be repacked ?

2236 Views 15 Replies 6 Participants Last post by oldfxr, 3 d ago

-alan-

Discussion Starter · 17 d ago

I know FXRs are not meant to be hushed... but the sound coming out of my '90 FXRT seems to be a tad on the excessive side. They sound like straight through drag-pipes:

Fuel tank Vehicle Tire Automotive lighting Automotive tire

The silencer sections are approx 16" long, and 3.5" diameter at the widest point. There are no obvious signs of baffles inside the silencer section that I can see. They have Harley Davidson embossed in flowing script on the upper section of the rear silencer. The sound is nice for a while, but starts to wear a little after 10-20 miles of full-on aural assault

Can anybody tell me (i) if they are standard FXR pipes - and (ii) whether they can be repacked to tame the noise back a bit ?

See less See more

Reactions: 1

1 - 16 of 16 Posts

Brand'd

· #2 · 17 d ago

If it's new to you and you don't know it's history it's possible the mufflers have been "punched". Very typical on those by riders that just want louder pipes or are trying to get more power. There's usually a baffle about halfway into the muffler. They're removed and either driven out with a pipe and hammer or drilled with a hole saw. Can you see inside? If they were removed I don't think there's much you can do to quiet them. You may want to search for some stock take offs that will fit. Now anytime you change the back pressure in an exhaust you need to also change the fuel mixture and possibly the air cleaner. Air and fuel in, needs to match air out so to speak.

Reactions: 1

-alan-

Discussion Starter · #3 · 17 d ago

Thanks Brand'd, yeah there's no obstruction anywhere in the silencer. I put a piece of old hosepipe in there to check - feels like it'd easily go all the way back to the exhaust valve if I put enough in.
If I want it quieter, guess I need either a replacement set of slip-ons, or to start thinking about replacing the whole lot.

Quick question - a lot of the mufflers / silencers on bikes with the staggered pipes from the factory look pretty similar. Are they as interchangeable as they look - or can I look at take-offs from older model Dyna/Sportsters and the like ?

Greg55_99

· #4 · 17 d ago

I had the exact same problem you have now. I got a set of stock FXRD pipes. I put on the pipes and fired her up for a sound check. Got a wicked "BRAP" coming out of one side. Pulled off the muffler and saw daylight through it. Somebody before me had punched out the metal disk in the baffle and turned it into a Cherry Bomb. Bad news. So, I figured out the approximate diameter of the "throat" section, welded up the center of a flat washer I had and carefully pressed that into the intake side so it rests on the ring left by the original disk. Fit is real tight. Put muffler back on and fired her up. Real quiet like stock now. Problem solved.

Greg

Reactions: 2

-alan-

Discussion Starter · #5 · 17 d ago

That sounds worth investigating - and a lot easier than trying to source replacement tail-pipes

Hey - thanks Greg!

Greg55_99

· #6 · 17 d ago

No problem. Let me explain in a little detail how I did it.

1. Hold muffler between your knees next to your tool box.
2. Start by putting sockets onto a long extension and put them into the muffler from the intake side.
3. When you find a socket that barely fits into the throat, put that one off to the side.
4. Keep going with sockets until you find one that barely does NOT fit. Put that one off to the side.
5. Take both of those sockets to a hardware store and find some washers that are the size that falls between them.
6. Check to see if the washer drops in. If it falls all the way in, too small. If it falls and barely hangs against the throat, OK.
7. Weld up the center. You may also have to trim a bit off with a file to get it to barely get in there.
8. Heat up the inside of the muffler with a heat gun for a while to get the throat to expand.
9. Drop the washer in and drive it against the ring with you socket and extension. Use a small socket, not a big one.

Worked for me. Cheap. Exhaust gas pushes the washer against the ring and the heat expands it in place. No rattle. Quiet. Back to stock.

Greg

See less See more

Reactions: 4

-alan-

Discussion Starter · #7 · 17 d ago

That's excellent - a great how-to on 'rebaffling' a punched-out silencer

I like your approach. I dont have welding kit, but can work around it by using a Dremel to cut the required size disk out of some old mild steel instead of going the washer/welder route.

That's going to be the newest addition to the Sort-this-FXR list.

Thank you again Greg - very much appreciated.
Alan

Reactions: 1

Racepres

· #8 · 16 d ago

Greg55_99 said:
I had the exact same problem you have now. I got a set of stock FXRD pipes. I put on the pipes and fired her up for a sound check. Got a wicked "BRAP" coming out of one side. Pulled off the muffler and saw daylight through it. Somebody before me had punched out the metal disk in the baffle and turned it into a Cherry Bomb. Bad news. So, I figured out the approximate diameter of the "throat" section, welded up the center of a flat washer I had and carefully pressed that into the intake side so it rests on the ring left by the original disk. Fit is real tight. Put muffler back on and fired her up. Real quiet like stock now. Problem solved.

Greg

Cherry bombs worked because they were Not straight thru...always oriented at an angle... bounced the "wave" off the Internal Baffles.. just to take that Jap Bike "Brap" noise Out!! yes...the angles plate works somewhat the same

Brand'd

· #9 · 16 d ago

Again, I'll caution you about changing the "mix" of the air/fuel/exhaust ratios. If you have EFI it's more difficult to check AFR's unless you have a tuning system/computer/laptop. If you're carb'd you can read your plugs a bit better. But lean conditions will make it pop on decels and rich conditions can foul plugs. Both conditions too far either way are bad for the motor. Like I said, it's very common for guys to punch the mufflers to make them sound better but without adding more fuel and air (via the air cleaner) it creates a lean condition. They already run lean stock.

-alan-

Discussion Starter · #10 · 16 d ago

It's a '90 FXR, so carb'd, and with no engine mods other than a Screaming Eagle ignition module and a freer flowing air-filter that I can see. Runs clean, with all of the telltale markers on the plugs indicating the mixture's good. The point about checking the fuelling after any change to the exhaust noted though,

Racepres said:
Cherry bombs worked because they were Not straight thru...always oriented at an angle... bounced the "wave" off the Internal Baffles.. just to take that Jap Bike "Brap" noise Out!! yes...the angles plate works somewhat the same

Coming from a two-stroke background with some insight into the pressure waves and reflections in expansion pipes work, but with next to no knowledge of how 4-stroke exhaust tuning works - I never really understood how the free-flowing pipes or cherry bombs were supposed to improve power.

Is it reasonable to assume that if the pipes have simply been opened out like mine, even with the fuelling adjusted, all you're ever likely to get is a lot more noise, but either little to zero gain (or in fact a slight loss) in true torque and power at most points across the rev-range ?

Reactions: 2

Racepres

· #11 · 15 d ago

-alan- said:
Coming from a two-stroke background with some insight into the pressure waves and reflections in expansion pipes work, but with next to no knowledge of how 4-stroke exhaust tuning works - I never really understood how the free-flowing pipes or cherry bombs were supposed to improve power.

Is it reasonable to assume that if the pipes have simply been opened out like mine, even with the fuelling adjusted, all you're ever likely to get is a lot more noise, but either little to zero gain (or in fact a slight loss) in true torque and power at most points across the rev-range ?

Alan, I need to pick your 2-stroke Brain... 2-stroke folks absolutely Understand Reversion!!!
Reversion is Important in a 4-stroke also.. You will Understand when I say that High Speede Gases travel the center, and low speed gass, the edge... I can prove that simply Eliminating (reversion trap) reversiopn helped My Dragbike, and others who gave it a real try... Also explains why, the Crossover Pipe Works (certainly Street applications),
I believe that even straight thru Mufflers, with a Baffle outside edge, Takes some "bite" out of Both "rash noise", and some bit of Reversion. lends Manners when applied to Drag Pipes, Certainly..
Anyway... we will get together when we both gots some Time...
Later my Friend...look forward to Learning some of that 2-stroke Magic!!!!

Reactions: 2

oldfxr

· #12 · 10 d ago

-alan- said:
I know FXRs are not meant to be hushed... but the sound coming out of my '90 FXRT seems to be a tad on the excessive side. They sound like straight through drag-pipes:

View attachment 275815

The silencer sections are approx 16" long, and 3.5" diameter at the widest point. There are no obvious signs of baffles inside the silencer section that I can see. They have Harley Davidson embossed in flowing script on the upper section of the rear silencer. The sound is nice for a while, but starts to wear a little after 10-20 miles of full-on aural assault

Can anybody tell me (i) if they are standard FXR pipes - and (ii) whether they can be repacked to tame the noise back a bit ?

Those don't look like the originals - mine had the originals, and they were a similar shape but much fatter. I put the Screamin' Eagle mufflers on mine, and they sound JUST right, but I don't think Harley sells them anymore. They have the script on just one of them, as you indicate you have, so these might be the Screamin' Eagle mufflers but punched out, as others have said. I don't like open or really loud pipes, but I think these have a nice, pronounced rumble. No "brap, brap."

Reactions: 1

Rilo

· #13 · 9 d ago

i

-alan- said:
I know FXRs are not meant to be hushed... but the sound coming out of my '90 FXRT seems to be a tad on the excessive side. They sound like straight through drag-pipes:

View attachment 275815

The silencer sections are approx 16" long, and 3.5" diameter at the widest point. There are no obvious signs of baffles inside the silencer section that I can see. They have Harley Davidson embossed in flowing script on the upper section of the rear silencer. The sound is nice for a while, but starts to wear a little after 10-20 miles of full-on aural assault

Can anybody tell me (i) if they are standard FXR pipes - and (ii) whether they can be repacked to tame the noise back a bit ?

I just put a set of slip ons that are a little loud , I got a set of baffles that fit inside them on ebay for less than $20 that quiet them down some .

Reactions: 1

Greg55_99

· #14 · 9 d ago

If you wrap them, you can quiet them down a tad more. They'll still be loud, just not LOUD.

See less See more

Reactions: 2

-alan-

Discussion Starter · #15 · 9 d ago

Thanks guys.

oldfxr said:
Those don't look like the originals - mine had the originals, and they were a similar shape but much fatter. I put the Screamin' Eagle mufflers on mine, and they sound JUST right, but I don't think Harley sells them anymore. They have the script on just one of them, as you indicate you have, so these might be the Screamin' Eagle mufflers but punched out, as others have said. I don't like open or really loud pipes, but I think these have a nice, pronounced rumble. No "brap, brap."

That does certainly tie in with my gut feel - both my old Ironhead 1000cc Sportster and 1340 Dyna had similar type exhaust arrangements, but with with larger diameter muffler/silencers than theses ones on the FXR. I had wondered whether these might be replacements - either factory SE brand or aftermarket.

Had a closer look at the pipes there, and the baffles have been removed in their entirety - not just punched out. I don't like the noise - it just sounds ignorant - but worse is the fact that without any kind of baffle in there I have no doubt the engine torque curve will be suffering badly. Have noticed a bit of a hesitation at one point in the rev range under acceleration already, which I thought was just poor selection or set-up with jetting/needles

Decided to do exactly as Rilo has done, and ordered a set of mild steel baffles to bolt into it sooner rather than later. Kill two birds with one stone possibly..

Don't intend to repack them with matting just yet - shall keep that as the back option - but in the interim will wait and see what the sound is like. Shall report back in due course gentlemen.

See less See more

Reactions: 1

oldfxr

· #16 · 3 d ago

-alan- said:
Thanks guys.

That does certainly tie in with my gut feel - both my old Ironhead 1000cc Sportster and 1340 Dyna had similar type exhaust arrangements, but with with larger diameter muffler/silencers than theses ones on the FXR. I had wondered whether these might be replacements - either factory SE brand or aftermarket.

Had a closer look at the pipes there, and the baffles have been removed in their entirety - not just punched out. I don't like the noise - it just sounds ignorant - but worse is the fact that without any kind of baffle in there I have no doubt the engine torque curve will be suffering badly. Have noticed a bit of a hesitation at one point in the rev range under acceleration already, which I thought was just poor selection or set-up with jetting/needles

Decided to do exactly as Rilo has done, and ordered a set of mild steel baffles to bolt into it sooner rather than later. Kill two birds with one stone possibly..

Don't intend to repack them with matting just yet - shall keep that as the back option - but in the interim will wait and see what the sound is like. Shall report back in due course gentlemen.

You might also sniff around and see if some dealer or someone else on Ebay, or whatever, has some intact SE mufflers. I like their sound a lot.

1 - 16 of 16 Posts