Newbie questions about exhaust noise and safety

[CRStep]

As we all know, the NC is extremely quiet, and while I am not a fan of loud, obnoxious open pipes on bikes, I can't help but wonder if I should install an aftermarket exhaust for a little boost of noise. I have surprised a few pedestrians riding around town because they did not hear me coming (no close calls or anything, just surprised expressions on their faces). I don't want to create a big change, but just a little more presence on the road for safety. I have read just about every thread I can find on aftermarket exhausts, and it sounds like people who feel they want one are generally happy with what they purchase, whether it is leo vance, yoshimura, delkevic, or danmoto. I can't tell from what I've read if an aftermarket exhaust affects bike performance in any real way, and I don't want to install anything that would muck around with the systems.

Specifically, I am asking three things:
1. Is there any credence to increasing the noise for safety reasons? (only talking a minor change, nothing that will adversely affect the neighborhood)
2. Are there any reasons not to install an aftermarket exhaust related to bike performance and fuel economy? (here's a chance for anyone's anecdotal evidence)
3. Does it really matter what brand I go with? They vary so widely in price and seem to have the same positive responses by the purchasers regardless of brand.

Thanks for any input you can give me. I don't like to rehash any old info, but my research gave me conflicting information or just gaps in what I am trying to figure out.

 

[DirtFlier]

Ask your insurance company if they'll give you a discount for having loud pipes similar to a discount for taking an MSF course? I'm sure the answer will be "no."

 

[Grey1one]

I put the Yoshimura R-77 on mine, a bit louder/growlier, but if I rev the bike to alert someone of my presence it has a much better chance of getting their attention. Under "normal" riding conditions pedestrians usually don't even look around to see me as I go by them.

 

[bamamate]

A loud pipes thread is opening a big can of worms. To my knowledge there is no study or proof that louder pipes save lives. The majority of sound is channeled behind you which I don't see where that helps. On the other hand noise pollution is a real issue and is why governments world wide are putting in noise level standards for vehicles. I'm sure there are cases where loud pipes played a part in saving a life but taking an MSF class and putting in to practice what you learned does save lives. Many insurance companies give discounts for completion of the basic rider class.

I haven't seen proof that a slip-on muffler gives any significant performance benefit. The bike has a catalytic converter which is more likely the biggest bottleneck in the exhaust. There is one company that sells a complete exhaust that removes the converter.
I personally would like a little more growl to the bike. Something along the line of how the African Twin sounds. There is no best one to get. Some are louder than others and then there are the aesthetics to consider. Some can have an optional quiet core insert so if it is too loud you can tone it down. For big bucks there is a dual exhaust setup that looks pretty cool. It all comes down to a personal choice.

 

[670cc]

I don't know anything about catalytic converters causing restrictions, but I can't imagine any reason Honda engineers would spec a cat that was not sufficient size for the engine. Why do many people assume that the catalytic converter is a bottleneck? Just as Honda chose the right size throttle body and the right size valves, wouldn't they also put on an appropriately sized cat? They can make them whatever size you want.

 

[Deleted member 4929]

1. No.
2. None, other than to realize that minimal performance improvements, if any, result.
3. Perhaps. No real data on these $100 slip-ons; good chance they actually decrease power output; may self destruct before 10K miles. But they make more noise! Other extreme being a $500 slip on that yields the same minimal improvements (which is what you get with a NC) as a quality mid priced silencer.

 

[bamamate]

I don't know anything about catalytic converters causing restrictions, but I can't imagine any reason Honda engineers would spec a cat that was not sufficient size for the engine. Why do many people assume that the catalytic converter is a bottleneck? Just as Honda chose the right size throttle body and the right size valves, wouldn't they also put on an appropriately sized cat? They can make them whatever size you want.

I am carrying over from the automotive side where there is apples to apples testing and assuming that it also applies to the motorcycle side. Manufacturers make the cats for pollution and longevity and not so much for flow characteristics which is totally understandable since they have to warranty the cat for 100k miles.

As an example, I don't remember the exact numbers, magazine took the 6.2L GM truck engine and engine dyno tested stock, then aftermarket cat back exhaust, then high flow aftermarket cats. Each gave a significant gain and the end results was something like 50hp gain. They also put on headers in there somewhere. I believe they also showed a slight increase in mpg. I remembered that article because I wondered what it would do with the 5.3L that I have in my truck but the cost seemed too much for me. Now the question is will the aftermarket cat last as long as the stock.

 

[CRStep]

Thanks for your input, everyone.

 

[ld_rider]

I have surprised a few pedestrians riding around town because they did not hear me coming

Stay off the sidewalk and keep to the road, you will startle fewer pedestrians that way.

You should have a button somewhere on your handlebars that will make a "toot-toot" noise if you press it. Try it!



If you do decide to go with pipes to announce your presence, I recommend a nice Akrapovic. First, because just saying the word Akropovic !!! is cool and second, it will give your Eco-friendly commuter bike a bit of street cred...

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

 

[ld_rider]

I think it is obvious to anyone with a couple of ears that loud noise is an attention getter and something we notice. It's how we are wired. Fire engines and other emergency vehicles run sirens for a reason, other than just for S&Gs...The fact is loud pipes probably do save lives..They just gotta be really, REALLY loud.

They also are not as effective in saving your bacon as riding with a helmet, protective gear, and while sober. So if "saving lives" is the primary goal, there are better methods, but loud noises are noticed. We all have horns for a reason ;-)

FYI -Removing the cats is a federal offense (and multi-thousand dollar fine) , as is putting on any aftermarket pipe that isn't EPA approved (and a consequently meets the 84db standard IIRC). My motorcycle is inspected every year here in Maine and they do look for stamped EPA approval on the muffler.

 

[MichaelJohn]

As bamamate said, this is a real can of worms. I think that "Loud pipes save lives" is a gross overstatement. However, I am convinced from real world experience that my aftermarket Leo Vince pipe has made me more noticeable on the road. My exhaust is quite a bit louder than stock but it is nowhere near average Harley loud, which was obvious to me again today when one pulled up next to me and completely drowned me out. I got into a long discussion about this on the Zero forum when I posted that I felt safer on my Honda than my Zero. I got a good flaming for that with most of the criticism saying that a motorcyclist should never depend on other drivers for his safety. That is a valid point but I didn't mean to say that one can relax and depend on being heard, I meant that exhaust noise is another way to make our presence known - just like running with lights on, adding extra lights, wearing bright gear, etc. As to exhaust noise being behind the bike I find that bikes are quite audible when approaching. When I am sitting in my office in downtown Oakland I hear motorcycles coming and going all the time. When you are on downtown streets with lots of buildings the sound reverberates. I hear motorcycles 5-10 seconds before they pass by my office and these are not all super-loud bikes either. I am not at all advocating eardrum-breaking exhaust, just something that you notice when it passes by. I know that on my Zero I have to be extra careful around pedestrians. I had one idiot on a bicycle ride right in front of me against a red light at an intersection and I couldn't avoid hitting him. It was night, he wasn't looking and had no idea i was coming. I hit his back wheel and spun him around like a top and down he went. Luckily he was more embarrassed than hurt and he walked his damaged bike away apologizing. I am almost certain that he would have heard me coming on the Honda.

As far as I know, there is no definitive proof about whether louder bikes are safer or not. I have seen the Hurt Report cited as a refutation of "Loud pipes save lives" but I read it and it does not mention exhaust sound at all. All it says is that there is a higher accident rate with modified bikes but it doesn't mention exhaust anywhere.

I know that this can be a divisive issue but I believe that ANYTHING that makes us more noticeable is a good thing. I put my pipe on mainly to give the bike a bit more character since for me the stock pipe just didn't do it but I have seen that people notice me more now. I don't like super loud bikes but I think that some volume can be a good thing. Am I adding to noise pollution? I don't really think so, but if I am I will be selfish and say that if my exhaust makes me even a little more noticeable on the road then others will just have to live with it. There are worse things in the world than loud motorcycles.

 

[Deleted member 1183]

Imho the 2012 NC silencer is too quiet. I have had several encounters with cyclists in the mountains where they simply did not hear me coming behind them. Needless to say I was aware that they could not hear me and took the appropriate action. There is no such problem with the pipe on my Triumph which is OEM and the same year. Likewise my newly acquired AT has a robust exhaust sound. I believe the 2016 NC's have a more robust sound also. As such that is sufficient proof for me that Honda have recognised the issue.

 

[Fuzzy]

I believe it is beneficial to have pipes loud enough for pedestrians and animals to hear you coming. That is a little louder than Honda stock, but not Harley loud. Harley loud aimed behind is little help to a vehicle ahead with closed windows and radio on. Fire engines have their speakers pointed ahead not behind.

I know a fellow who walked out of one sawmill building going across the yard to another. He left his earplugs in. The sidewalk was parallel to a rail siding then crossed the siding. A rail car was being moved up the siding in the same direction as he was walking. Just as the rear of rail car got beside him he turned left and bumped into it. A railcar rolling slowly down a siding makes plenty of noise, but not enough to get past his earplugs or a closed window on a car. Luckily the guy just had a good scare and was not hurt.

 

[kpinvt]

Stay off the sidewalk and keep to the road, you will startle fewer pedestrians that way.

You should have a button somewhere on your handlebars that will make a "toot-toot" noise if you press it. Try it!



If you do decide to go with pipes to announce your presence, I recommend a nice Akrapovic. First, because just saying the word Akropovic !!! is cool and second, it will give your Eco-friendly commuter bike a bit of street cred...

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

A comparison of three exhaust cans, stock, Leo Vince and Akropovic!!.

https://www.youtube.com/watch?v=WiyyoPeGHb0

I like the way my quiet bike growls at WOT with the stock can.

 

[ronsaw]

As bamamate said, this is a real can of worms. I think that "Loud pipes save lives" is a gross overstatement. However, I am convinced from real world experience that my aftermarket Leo Vince pipe has made me more noticeable on the road. My exhaust is quite a bit louder than stock but it is nowhere near average Harley loud, which was obvious to me again today when one pulled up next to me and completely drowned me out. I got into a long discussion about this on the Zero forum when I posted that I felt safer on my Honda than my Zero. I got a good flaming for that with most of the criticism saying that a motorcyclist should never depend on other drivers for his safety. That is a valid point but I didn't mean to say that one can relax and depend on being heard, I meant that exhaust noise is another way to make our presence known - just like running with lights on, adding extra lights, wearing bright gear, etc. As to exhaust noise being behind the bike I find that bikes are quite audible when approaching. When I am sitting in my office in downtown Oakland I hear motorcycles coming and going all the time. When you are on downtown streets with lots of buildings the sound reverberates. I hear motorcycles 5-10 seconds before they pass by my office and these are not all super-loud bikes either. I am not at all advocating eardrum-breaking exhaust, just something that you notice when it passes by. I know that on my Zero I have to be extra careful around pedestrians. I had one idiot on a bicycle ride right in front of me against a red light at an intersection and I couldn't avoid hitting him. It was night, he wasn't looking and had no idea i was coming. I hit his back wheel and spun him around like a top and down he went. Luckily he was more embarrassed than hurt and he walked his damaged bike away apologizing. I am almost certain that he would have heard me coming on the Honda.

As far as I know, there is no definitive proof about whether louder bikes are safer or not. I have seen the Hurt Report cited as a refutation of "Loud pipes save lives" but I read it and it does not mention exhaust sound at all. All it says is that there is a higher accident rate with modified bikes but it doesn't mention exhaust anywhere.

I know that this can be a divisive issue but I believe that ANYTHING that makes us more noticeable is a good thing. I put my pipe on mainly to give the bike a bit more character since for me the stock pipe just didn't do it but I have seen that people notice me more now. I don't like super loud bikes but I think that some volume can be a good thing. Am I adding to noise pollution? I don't really think so, but if I am I will be selfish and say that if my exhaust makes me even a little more noticeable on the road then others will just have to live with it. There are worse things in the world than loud motorcycles.

Well said - I agree completely!

 

[Beemerphile]

I'm trying to remember if I have ever known of anyone changing their opinion on this after hearing one that differs... Nope.

 

[johnakay]

eat plenty of beans and hold onto your fart till you want to alert some poor sod. lol

 

[MichaelJohn]

I'm trying to remember if I have ever known of anyone changing their opinion on this after hearing one that differs... Nope.

View attachment 29761

You know of one now. I have definitely changed my mind on this one. I used to be an electric zealot who thought that "loud pipes save lives" was simply a justification for the HD and screaming sport bike crowds. Then I read a very well-reasoned article about the subject that made me really examine my position and I decided that I couldn't fully support it, that is, i couldn't disprove the "loud pipes" theory. The "saving lives" part is extreme, and I think it is often used more as a justification for a loud motorcycle than a true belief in the statement. That does not, however, mean that there is nothing to the statement. I used to think that it was total BS, now I don't. Some horses don't die that easily.

 

[MZ5]

I don't know anything about catalytic converters causing restrictions, but I can't imagine any reason Honda engineers would spec a cat that was not sufficient size for the engine. Why do many people assume that the catalytic converter is a bottleneck?

Probably because about _every_ aftermarket, high-flow catalyst ever installed into any car shows a net hp gain on a dyno.

That's not to say that emissions performance is the same after such a change. It never is. Nevertheless, a catalyst _is_ a restriction, it's just one that's required.

 

[CRStep]

I really appreciate all of the constructive comments. I definitely did not want to open a can of worms here. I agree that I've always thought that "loud pipes save lives" was primarily a justification to be a loud hooligan, but I'm pretty sure my NC is quieter than the 250cc Vespa I used to own. I was thinking that if on a noise scale from 1 to 10 Honda is a 1, and obnoxious bikes are a 10, I'd like to be maybe a 3? 4? I believe strongly in using protective gear, taking advantage of safety education, etc., and yes, using the "toot toot" horn. Thank you for the links to sound clips, and you all have given me enough to think about to form a good conclusion on this issue.