Exhaust baffle and packing replacement

[slabghost]

Ask at the parts store they are the big washers with I think the 3/8 hole used for fenders on cars.

 

[slabghost]

Forget the fender washer idea. Now that I see how the tangs are inside I think it's impossible to install a washer and most likely ineffective.

 

[mcgovern61]

If I remember correctly, to kill the explosion sound, they need to pass around inside chambers. I am think of pulling the baffles, plugging the inside end of the pipe, cutting back 1/3 of the baffle material from the inside end to center forcing the sound to go around the baffle pipe, hit the baffle material and enter the pipe through the side holes and then out? Cheap and easy. I'll try it this weekend.

 

[dan filipi]

I think that might create too much back pressure but maybe not.

 

[mcgovern61]

I think that might create too much back pressure but maybe not.

The holes in the baffle pipe are pretty big. If I can maintain an opening that is 200% the size of the center pipe ID through the holes where the tangs are, maybe it will not increase the BP too much. The alteration is simple and I am not modifying any of the metal parts so hopefully it will work. If not, I can put it back the way it was and live with it.

 

[dan filipi]

I was reading a bit about how mufflers work, very scientoofical.

Apparently it has a lot to do with evening out and cancelling sound waves and high pressure to low pressure effects and a whole bunch of other stuff that's way over my head.

I like this trial and error your doing Gerry, more fun.

 

[mcgovern61]

I was reading a bit about how mufflers work, very scientoofical.

Apparently it has a lot to do with evening out and cancelling sound waves and high pressure to low pressure effects and a whole bunch of other stuff that's way over my head.

I like this trial and error your doing Gerry, more fun.

Did some research too while I was in Alabama this week. Turns out the baffles in our bikes are full of holes specifically to allow the high pressure explosions that come out of the main muffler to expand into the holes to be absorbed by the packing material. Apparently they are designed like a cherry bomb in that they do not impede the flow of gases. The more holes, the quieter the sound. Fewer holes and more pipe - louder. (I can attest to that!)

Armed with this info, I am going to try my experiment with shoving a carriage bolt down the front side to block the high pressure explosions and send them down around the baffle and forcing them through the side holes. (Minor form of cancelling) Won't be tuned, but worth a try. :builder:

 

[scdmarx]

Ain't had to build a muffler yet, but my son and me were experimanting with noise supressing designs :ahem:
We tried various baffle with packing configurations, oil filters, but the most effective by far was the cylinder with stacked washers. Space several washers through the pipe to create many chambers.
Sound is vibrating air. You need to difuse those vibrations. With cancelling frequency, absorbtion, or "?".

 

[mcgovern61]

Cancelling explosions with chambers is the best idea! I tried the carraige bolt down the front and cutting back the packing material....it was quieter, but it started that popping noise again! :head bang: :cheeky:

Next, I put the old baffle in on the left side with the new packing and even though it is in real bad shape, it did quiet down the sound! :clapping:

So, my conclusion is.....based on the design, you need that heavily perforated pipe to dispel the sound into the packing without putting a restriction in front of the sound lest you get that ubly popping sound. Soooooo...I decided to take one of the HD baffles and cut off the pipe......remove the perf pipe from the broken right baffle and put them together. Installed it on the right side and...voila...it worked!! :yahoo:

Here is a video of the left side with the original Honda baffle and the right side has the modified HD baffle with the Honda perf pipe:

https://www.youtube.com/watch?v=HvQtkeFQvPQ



Here is a video at the same RPM with the unmodified baffle on the left and the modified one on the right. You can hear the slight popping on the left as compared to the modified one on the right:

https://www.youtube.com/watch?v=pbU6Z9YlG7Q



It may not be as quiet as I would like it, but I think I have a cheap winner here! :good: :salute:

 

[dan filipi]

That right one in the last vid sounds good.
Crazy that the perforated OEM baffle makes so much difference.

What do you think would have to be done to make it even quieter?

If I thought I could get mine out without destroying them I'd try the stacked washer SC mentioned.

 

[mcgovern61]

I like the idea of the stacked washers, but I do not have a welder so I cannot try it. I am going to modify the left baffle to match the right. Even though the perf pipe is wasted at the ends, it will sit in the packing real tight and keep the packing from collasping from the pressure. The HD end piece is then bolted in which keeps everything in. It would be nice to find someone that could make the original baffles.

 

[mcgovern61]

This exhaust system is stamped "meets EPA noise emission 83 dBa".

My boss has a decibel level analyzer that can record any sound level and give you a read back in dB or dBa. Next time I ride my bike in to work I will measure the dBa level and see if it is at or near 83 dBa. Then I will know for sure which way I need to go. If the sound is around 83 dBa, then I know that at least I am back to square one.

 

[mcgovern61]

Took the bike to work today! :yahoo:

I had a chance to measure the exhaust decibal level per the following guidlines:

https://www.ehow.com/how_6150114_measure ... noise.html

I also checked the EPA guidlines as found stamped on my muffler (83 dBa) and how to test and it is the same method.

Bike on center stand, 4000 RPM, 20" away from exhaust outlet (above the exhaust gas stream) and angled at 45 degrees, I got 95 dBa on the left side (HD baffle with tangs knocked down) and 93 dBa on the right side (HD end plate with the original Honda perf pipe) both sides repacked.

Looks like I need to try something else if I am going to at least get back to 83 dBa! :builder: :cheeky:

 

[dan filipi]

There ya go, 2 end baffles.
Wonder what that would sound like, way too long though.

 

[mcgovern61]

HOFFNASTY IS THE MAN!!!! arty: :thanks:

Got those tips in the mail today and they were in better shape than the pipes I have on the bike! :smilie_happy:

Popped the baffles out and took some of that baffle material (which was 3 layers thick to my one size fits all baffle material from Honda) and wrapped up the new baffles. They are in extraordinary condition compared to what came out. Worked them into my pipes and started up the bike.

:yahoo: :Egyptian: arty: :Egyptian: arty: :Egyptian: :Egyptian: :yahoo:

KNOCKED THAT SOUND RIGHT DOWN!!!!!

It now sounds like a Goldwing again! It seems the added back pressure has smartened up the engine if you will. Snap the throttle and the engine jumps now!! NO MORE POPPING SOUNDS!!!!!

(Can ya tell I'm happy!) :music3:

 

[mcgovern61]

Makes me what to start building new baffles and sell them now that I see what difference a good set of baffles can do!

 

[dan filipi]

Makes me what to start building new baffles and sell them now that I see what difference a good set of baffles can do!

I'd buy a set.

 

[mcgovern61]

Took the bike to work today! :yahoo:

I had a chance to measure the exhaust decibal level per the following guidlines:

https://www.ehow.com/how_6150114_measure ... noise.html

I also checked the EPA guidlines as found stamped on my muffler (83 dBa) and how to test and it is the same method.

Bike on center stand, 4000 RPM, 20" away from exhaust outlet (above the exhaust gas stream) and angled at 45 degrees, I got 95 dBa on the left side (HD baffle with tangs knocked down) and 93 dBa on the right side (HD end plate with the original Honda perf pipe) both sides repacked.

Looks like I need to try something else if I am going to at least get back to 83 dBa! :builder: :cheeky:

Got a chance to check the dB level again with the correct baffles and now it measures around 86 dBa! :Egyptian: :Egyptian:

Sooooo....that does prove that good condition Honda OEM baffles are the best choice if you want to get near the original sound levels. Now I do not want to give the impression that it is sewing machine quiet like a '76 GL1000 (there is still that deeper sound in the exhaust) but the sound has been reduced to a level that on the highway at 75 MPH (this mornig!), I can easily hear a person speaking on the radio.

The new thing that has cropped up is.....now I can hear engine noises that I never heard before! (Valves might need adjusting)

 

[joedrum]

:yahoo: :yahoo:

 

[king1]

Why not just two HD sportster mufflers? Thier the first thing a new HD owner gets rid of.. and can be bought on the cheap.($20) Have two on my '83I ... Took about an hour to mount.. The tinest bit throaty on the sound getting into the throttle. But i too can hear things i could not before... Had straight baffles prior.. I could be heard for over 3 blocks.! Probably below 83db now.? :good: