Quieter than stock?

nicecruise

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Hello fellow nc enthusiasts. Have owned nc750s for approx three months, am wondering is anyone aware of a quieter slip on exhaust than the stock exhaust? I know its already a quiet bike however, just wondering have done a few google searches and couldn't find anything. I previously owned a CBR 500r and the thing was quieter than a bicycle at idle, which was great for me as I like keep quiet on early morning commutes. The nc seems more thuddier than the cbr at idle, perhaps the bigger engine? Both being twins. Thanks in advance. Safe Riding. ATGATT.
 

670cc

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If there was an exhaust system quieter than stock, I would consider buying one. However, a large market for quiet aftermarket exhaust systems, in general, doesn’t seem to exist. Many people like motorcycle noise, but I definitely don’t like the noise. I’ve been an NC owner for 7.5 years and have yet to come across anyone offering a quieter than stock exhaust for it.

I sometimes think that OEMs intentionally make the stock exhaust almost as loud as legal regulations will allow, because their research says that’s what buyers would want.

Mechanical noise and intake noise are also factors contributing to overall engine noise. I don’t know how much of the NC engine‘s noise is mechanical and how much is intake and/or exhaust. I just know that when I can barely hear the engine, I’ve got my ear plugs seated well.
 

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There's just no market for a quiet exhaust. The exhaust on the NC750X was tuned to be thudding and throaty from the factory, and folks still change it out for louder cans. I came from a Rebel 500, with the same engine as your cbr, but tuned differently, and it was about the same sound wise. Intake noise is another matter. When I open the engine wide, it sounds like a vacuum cleaner under the frunk! How many miles do you have on yours? I bought mine first of November and have nearly 2000 miles, as we've had an exceptionally warm winter this year.
 

nicecruise

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Have put about 3000kms on mine so far, interesting to know I have seen the newer version I think 2019 onwards with a different looking exhaust but I expect they sound the same as mine (2018). How are you finding the NC so far any other observations? I have to say the seat/suspension is very hard. That's one thing I have noticed, I am going to look into modifying that somehow in the future.
 

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Thunderstick

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I am ecstatic with my NC750X! I'm a big fella and the suspension is fantastic with a little added preload on the rear shock. I find the saddle perfectly fine as I prefer a very firm seat. I'm still shocked at how much better it handles than the Rebel 500. It may not have a lot more HP, but it has more grunt at higher speeds, and gets better fuel economy than the CMX500. It just does everything I need a motorcycle to do, and does it very effectively!
 

nicecruise

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Wasn't aware preload was adjustable is this the case on NC750S? I have just checked rear shock seems to have adjustable cog however tool kit not including adjuster tool. Might have gone missing...
 

nicecruise

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Not sure if this thread is still live. However have come across a cheap exhaust online from A cbr929, it’s larger than current stock exhaust. Does anyone know if installed on my 750s will make the bike quieter?
 

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nicecruise

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Ok turned out the muffler I thought was cheap, isnt. So instead of buying a whole slip on, I’m going to try a baffle install.

Limited research online but I’m trying, I assume the stock muffler the nc comes with has already a baffle inside. So I am looking to install another one before the muffler. In the exhaust pipe itself. This is exposed if you remove the muffler heat guard, and the muffler itself. Roughly measured it 30mm diameter, should fit a fiberglass wrapped baffle in there nicely?

5D3A9728-C743-4E65-8BB2-F636427F8FB7.jpeg
E172C831-5E2F-44B4-9AD5-D5F30B3A1184.jpeg

(anyones advice who actualy knows what they’re talking about would be appreciated)

only doing this because I work at stupid oclock and want to keep as much as I can from disturbing my neighbours while still being able to take my bike to work.

so, should be as simple as finding right size diameter baffle. Wrapping with fiberglass and wire. drilling holes in exhaust pipe and inserting bolts to secure baffle. Reinstalling oem muffler and away we go. if you know this would work, or this would f*** up the machine please let me know. All I can think of is some possible power loss.

Thanks
 
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melensdad

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Be careful of changing the back pressure, not sure what sort of sensors the NC has for that, but it can cause issues if the back pressure is too high
 

Klap

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I too, found the NC700 a bit loud- My ST1300 is much quieter, but most of the engine is behind a large fairing too! Coming from a background of older, Airhead BMW's, any bike sounds kinda loud to me. My '71 R75/5 was so quiet that the valves were MUCH noisier than the exhaust.
I'll be watching this thread to see if anyone actually quiets it.
 

nicecruise

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Have you thought of getting another stock pipe and putting it on the other side? If you splice the pipe after the sensor, the engine shouldn't complain too much.
No I haven’t, that sounds like a great idea though. Will research. are you referring to a sensor in engine that monitors back pressure? Or is there a particular place in the exhaust assembly that has a sensor?
 

Doc True

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No I haven’t, that sounds like a great idea though. Will research. are you referring to a sensor in engine that monitors back pressure? Or is there a particular place in the exhaust assembly that has a sensor?

I have no idea how complicated this operation would be. It's just an idea that popped in my head.

There should be an O2 sensor in the pipe at some point that's part of the emissions monitoring system. If you alter the pipe before this system, it will send wonky signals to the ECU and alter how the engine works.

You may also be able to replace the stock muffler with the stock muffler from different model bike. Maybe a goldwing or concourse. If the pipe diameter is the same or similar, it should take less fabrication. People are always replacing stock mufflers for louder ones. I would think that there would be plenty available on Ebay
 

670cc

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No I haven’t, that sounds like a great idea though. Will research. are you referring to a sensor in engine that monitors back pressure? Or is there a particular place in the exhaust assembly that has a sensor?
The only sensor in the exhaust system is the O2 sensor and it is mounted to the exhaust pipe near the cylinder head, prior to the catalytic converter. See item 12 in this picture below. It does not measure back pressure.D8FD50E0-97D1-4DE6-B3A7-FF031C1E388B.jpeg
 
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