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 Post subject: Re: NS400R too loud
PostPosted: Tue Mar 28, 2017 7:05 pm 
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Thats what I`m expecting to find tomorrow (Pictures from Google)

Image

Image

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My bikes:
RD500 YPVS 1GE
RD350 YPVS 31K 1985
Honda NS400R NC19
Honda CBR 1000 RR SC57
Yamaha R1 RN04


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 Post subject: Re: NS400R too loud
PostPosted: Tue Mar 28, 2017 7:08 pm 
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My NS400R isn't all that loud, at least compared to my other bikes. I think it is the quietest of them all.

One way I have removed carbon is to put the whole silencer in solvent and let it sit for a couple of days. That dissolves the carbon in the baffles. I then give them a good shake and use a brush inside the baffles to dislodge and remove the carbon. Then I run solvent through them to flush them clean. Then I hang the silencers and allow the solvent to drain out. Once most of the solvent has drained I ignite the end of the silencer and let the solvent inside burn. One the burning is finished the solvent is gone and the baffles are clean(er).

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1985 RZ500
1985 RZ500 Project Bike
1986 RG500 ATR
1986 NS400R
1987 TZR250
2007 DL650 VStrom
2014 Triumph Thruxton
1979 Pontiac Trans Am with modified 1969 Olds 455 (7.5 L) 400++ HP, 500++ Ft/Lbs


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 Post subject: Re: NS400R too loud
PostPosted: Tue Mar 28, 2017 7:10 pm 
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Speed Freak wrote:
Thats what I`m expecting to find tomorrow (Pictures from Google)


Airbox mods will typically create more intake noise, but not create more exhaust noise. I have modified many airboxes and have never seen an increase in exhaust noise.

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1985 RZ500
1985 RZ500 Project Bike
1986 RG500 ATR
1986 NS400R
1987 TZR250
2007 DL650 VStrom
2014 Triumph Thruxton
1979 Pontiac Trans Am with modified 1969 Olds 455 (7.5 L) 400++ HP, 500++ Ft/Lbs


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 Post subject: Re: NS400R too loud
PostPosted: Wed Mar 29, 2017 3:58 am 
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But the intake noise can be very loud, it`s more a "barking" sound when the throttle is opened.
That would explain why there is not much difference when the exhaust is full of wool :smt003

By the way, my RD350 is not completely stock, it has an modified upper air filter case according to MK`s manual.
Maybe this is the reason why it has the same noise level :smt003

Let`s see in the evening... Can`t wait until I can go home from work :mrgreen:

By the way, there is another method for cleaning the pipes.
Put some fuel in (not too much, just for starting the process), igite it and blow with a hot air gun through the pipe.
With enough oxygen and heat the carbon itself starts to burn - but as said, there will be no wool left over after that.

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My bikes:
RD500 YPVS 1GE
RD350 YPVS 31K 1985
Honda NS400R NC19
Honda CBR 1000 RR SC57
Yamaha R1 RN04


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 Post subject: Re: NS400R too loud
PostPosted: Wed Mar 29, 2017 12:17 pm 
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As i remember well (i'm getting old, i know): The south african bikes had an airfilter modification standard on these bikes.


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 Post subject: Re: NS400R too loud
PostPosted: Wed Mar 29, 2017 4:45 pm 
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SA bikes had a lower displacement. 373 ccs compared to 387 ccs for everyone else.

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1985 RZ500
1985 RZ500 Project Bike
1986 RG500 ATR
1986 NS400R
1987 TZR250
2007 DL650 VStrom
2014 Triumph Thruxton
1979 Pontiac Trans Am with modified 1969 Olds 455 (7.5 L) 400++ HP, 500++ Ft/Lbs


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 Post subject: Re: NS400R too loud
PostPosted: Wed Mar 29, 2017 5:52 pm 
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Air filter case is checked - it is as it came from the factory...
Only one of the 2 plugs (don`t understand the function of them) in the lower airbox is out of place.
But this will not cause too much noise.

Need to remove the lower airbox to push it back in completely.

Would be too easy... :smt011
So it has to be exhaust noise.

I hope I will come home from work before 10pm tomorrow :smt011

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My bikes:
RD500 YPVS 1GE
RD350 YPVS 31K 1985
Honda NS400R NC19
Honda CBR 1000 RR SC57
Yamaha R1 RN04


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 Post subject: Re: NS400R too loud
PostPosted: Thu Mar 30, 2017 6:20 pm 
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Today another try to get it silent...

1) Intake is now 100% stock and both plugs (for synchronisation) are fitted how they should be.
2) Reduction of the stinger diameter to 8mm with washers
3) Glass wool in the front of the silecer...

My expectation: It will not start because the exhausts are completely closed :smt005
But it was possible to start and it was slightly better - maybe enough for the check, maybe not...

Only problem, on the test ride it was not possible to get it over 5000rpm...
So not a real solution, too risky - if they find this measures it will get even more complex to get the registration :smt009

I was looking inside the silencer - is it really stadard that they are nearly empty?
Here is a drawing what I expect to find inside them:
Image

Is there no insert in the end of the silencer like the inserts of the RD350 31K?
The guy at the registration check was sure that there are some inserts missing (I think this is bullsh**)

The inner perforated wall looks quite clean on all 3, only the lower right (the loudest) has a lot of clogged holes in the end pipe.
Tomorrow or on saturday I will buy a steel brush that fits into the pipe and remove the carbon.
Seems that there is still some wool behind.

Here some pictures...

Inside the upper pipe (not the silencer):
Image

Image

Look inside the silencer end pipes (one with removed beauty end cap and one with this cap):
Image

Image

Image

Image

Look inside the silencer front pipe:
Image

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My bikes:
RD500 YPVS 1GE
RD350 YPVS 31K 1985
Honda NS400R NC19
Honda CBR 1000 RR SC57
Yamaha R1 RN04


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 Post subject: Re: NS400R too loud
PostPosted: Thu Mar 30, 2017 6:27 pm 
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Have you checked the noise with the ATAC opened and closed?

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1985 RZ500
1985 RZ500 Project Bike
1986 RG500 ATR
1986 NS400R
1987 TZR250
2007 DL650 VStrom
2014 Triumph Thruxton
1979 Pontiac Trans Am with modified 1969 Olds 455 (7.5 L) 400++ HP, 500++ Ft/Lbs


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 Post subject: Re: NS400R too loud
PostPosted: Thu Mar 30, 2017 6:42 pm 
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Is there a difference?
They are only chambers with additional volume - I don`t expect that they will change the noise level?!

I expected that they are open at low rpm`s but I did not check if they work.

On the weekend I want to remove the whole exhaust pipes and burn the soot out of them.
Just need a place where nobody calls the fire brigade :smt003

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My bikes:
RD500 YPVS 1GE
RD350 YPVS 31K 1985
Honda NS400R NC19
Honda CBR 1000 RR SC57
Yamaha R1 RN04


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 Post subject: Re: NS400R too loud
PostPosted: Thu Mar 30, 2017 8:19 pm 
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They are open until 7500 RPM and then they close. It changes the pipe volume and affects the way wave pulses return to the cylinders. It can't hurt to check the difference in noise between opened and closed. They are open when you are checking at the test centre. You can unplug the solenoid and close them to see if there is a difference in the noise at idle speeds.

My 400 isn't loud with stock pipes. I think it has the lowest noise of all of my 2 strokes. I always thought all NS400Rs were quiet.

_________________
1985 RZ500
1985 RZ500 Project Bike
1986 RG500 ATR
1986 NS400R
1987 TZR250
2007 DL650 VStrom
2014 Triumph Thruxton
1979 Pontiac Trans Am with modified 1969 Olds 455 (7.5 L) 400++ HP, 500++ Ft/Lbs


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 Post subject: Re: NS400R too loud
PostPosted: Fri Mar 31, 2017 3:50 am 
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Worth a try, yes.
Maybe good to check if they work and also adjust them.

Planned to do this work when I have it registered to get the engine really warm to do all the adjustments etc.

I also did not expect that the noise level will be a problem of a Honda as they usually sound like vacuum cleaners when they come from factory.
If you google "NS400R sound" you can find a lot of different experiences with this bike.
One says "it sounds like a vacuum cleaner" and the other one says "it sounds like 3 highly tuned 50cc mopeds" and the next says "be happy about 100dB, you can sell your silencers as others have up to 108dB and would be happy about 100dB"

Seems that the dampening insert in the pipe itself also makes a lot of difference as I have found one forum entry where someone says "if you remove them the sound will change from vaccum cleaner to jolly moto pipes".
To remove them you have to cut it - mine have original welds all around so they have to be inside.

I`m switching all the time between cutting them open and do some "other" measures...
The "other" measures will not make me happy and cleaning them is not possible as 90% of the dampening effect will be on the inner wall, not in the last 10cm of the end pipe...

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My bikes:
RD500 YPVS 1GE
RD350 YPVS 31K 1985
Honda NS400R NC19
Honda CBR 1000 RR SC57
Yamaha R1 RN04


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 Post subject: Re: NS400R too loud
PostPosted: Fri Mar 31, 2017 5:28 am 
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Speed Freak wrote:
Worth a try, yes.
Maybe good to check if they work and also adjust them.


There isn't much to it Michael. They are either opened or closed. There is no in between. It's a very simple system, but works very well. Below 7500 RPM the bike is sluggish. At 7500 when the ATAC chambers close it becomes a rocket. 160 KPH in 3rd gear and I rarely get above 3rd gear. 3rd is where all the fun is.

_________________
1985 RZ500
1985 RZ500 Project Bike
1986 RG500 ATR
1986 NS400R
1987 TZR250
2007 DL650 VStrom
2014 Triumph Thruxton
1979 Pontiac Trans Am with modified 1969 Olds 455 (7.5 L) 400++ HP, 500++ Ft/Lbs


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 Post subject: Re: NS400R too loud
PostPosted: Fri Mar 31, 2017 1:35 pm 
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Miracle solved... Went to my Honda dealer today and asked if he knows someone with this bike.
There is only one - one call - original Austrian papers 102dB (tolerance+-3dB)
It`s funny, he knows this value because he was stopped by the police and they did not believe that this value is legal.

A lot of time wasted.
Waiting for the copy of the papers as this guy isn`t at home at the moment.

I just hope that there is only one number stamped on the silencers for all NS400R and this number is also in the Austrian papers.

Just a funny background story...
The Honda dealer was informed that there is a new Honda NS400R close to him (I`m living maybe 1km away from the dealer) because the technical checker (not the guy who is doing the office stuff) is from here and has good contacts to the dealer.
Austria is really small :mrgreen:

_________________
My bikes:
RD500 YPVS 1GE
RD350 YPVS 31K 1985
Honda NS400R NC19
Honda CBR 1000 RR SC57
Yamaha R1 RN04


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