Sound level fo Yosh R-77

[R1000]

I've measured the sound level from my R-77 system w and w/o the included dB-killer. The measurement was done 0.5 meters from the outlet @45 degree angle. I didn't bother to check at which RPM the measurement should be done for an inline four-stroker with the Busa's stroke, and just used 5600 RPM, which applies for a Honda Blackbird. The possibly slightly different norm-RPM for the Busa, having a longer stroke, would however not change the result much, at least not the dB-killer reduction.

The noise level was 102 dBA w/o dB-killer and 98 dBA with the dB-killer in place. I really like the Yosh dB-killer, it reduces the sound power level with more than 50% (3 dB is 50% power) and the engine performs very well with it. The human ear is not linear and it requires almost 10 dB to recognize the change as 50%. 4 dB is however a quite noticeable reduction and the dB-killer also change the sound spectrum to be less aggressive. The 4 dB will also guarantee that the bike will pass a legal ispection in this country (Sweden). Other rules may apply elswhere.

Next step will to check how much power the dB-killer eats when dynoing the bike in the next few weeks. Here is a short video from a previous sound measurements on the Blackbird, just to demonstrate the simple principle. The sound meter is an inexpensive unit (about 50 bucks), but calibrated within 0.2 dB at an accredited sound laboratory.

 

[Busa08]

Had Yosh R-22 was not right for me bought BROCK'S AH system

 

[Dobieman]

I would be interested to know the noise levels again after about 5K of use. Yosh says repack the canister every 5K or some crazy number like that. As it burns the packing it will get louder, just curious how much?

Maybe Warchild can give us some info on the volume increase since he is already at 25K now.....

 

[R1000]

Good point, I've thought of this myself on previous bikes, but never got the opportunity to record the sound level on a fresh system as done now.

 

[Warchild]

I would be interested to know the noise levels again after about 5K of use. Yosh says repack the canister every 5K or some crazy number like that. As it burns the packing it will get louder, just curious how much?

Maybe Warchild can give us some info on the volume increase since he is already at 25K now.....

I am sad to report my R-77 is CONSIDERABLY louder nowadays.... which is not surprising, since the pipe is just shy of 23,000 miles of use. Even with the DB Killer insert in place, I can still hear the pipe over my 34-NRR ear plugs.....

Have got a re-packing kit coming my way.... I am woefully overdue for a re-build. Which is my own fault... it's hard to take the bike off the road long enough to do significant PM work.

So, admittedly... as you can see below, my $hit is looking a little ragged here....  

 

[Dobieman]

I am sad to report my R-77 is CONSIDERABLY louder nowadays.... which is not surprising, since the pipe is just shy of 23,000 miles of use. Even with the DB Killer insert in place, I can still hear the pipe over my 34-NRR ear plugs.....

Have got a re-packing kit coming my way.... I am woefully overdue for a re-build. Which is my own fault... it's hard to take the bike off the road long enough to do significant PM work.

So, admittedly... as you can see below, my $hit is looking a little ragged here....  

Make sure to document the repack process for the rest of us who rely on your doing it first to find out how its done

 

[BusaWizard]

 

[Greenbean]

So, admittedly... as you can see below, my $hit is looking a little ragged here....  

Did you paint your hardware or ceramic coat? it looks good on there...