Announcement

Collapse
No announcement yet.

[GROM][DIY] Exhaust Sound Level

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • [GROM][DIY] Exhaust Sound Level

    I have a Yoshimura RS-2 exhaust on my Grom. It is a tad too loud (socially speaking) although I like the deep-ish note. The exhaust comes with a "DB Killer" insert (which wasn't installed on delivery) and I was curious to know what difference it makes. Using a sound level meter (accuracy +/- 3.5 dB, so only relative readings are useful) I found there was about a 3 - 4 dB difference when the DB killer was inserted compared with the non-DB killer level (at idle 80 - 81 dB w/o DBK, 77 -78 dB with DBK). Short blips showed this difference was about the same for higher revs (after warm-up).

    A 3 dB difference (half-power) is what is generally stated as the minimum change detectable by the human ear (although using headphones on a tone test I can just detect a 1 dB difference - but I am sensitive to noise) and so is not a big difference.

    A further test (and this is the DIY part) involved extending the short tube of the DB killer internally by a 160 mm long 32 mm OD tube. This reduced the level by another 2 - 3 dB. The tubing came from a cheap (AUD$8) solar light and looks to be SS.

    The standard setup without the extra quieting has the deepest note on idle, which is unfortunate. The only way I know to keep the deep note without the raspy bits is to have a longer section of absorbing material. There maybe another longer muffler which would slip on, but the Yoshi muffler looks nice visually.

    I'll ride around for a while with the DBK in to see if I am happy with the sound. If it is still too loud I will try the 'solar light' insert.

    Cheers

    Steve

  • #2
    I had a DB Killer for the Tonelli that made a fairly big difference, but I found I never bothered using it as I was always WAY less noisy than any of the Harleys with straightshots.

    The only people I have ever heard getting done for noise are either ridiculously loud, or getting pulled for something else. Never heard of a Monkey being pulled for noise, only larger bikes. Then again it all depends on your local policing.
    Rigby "No dude, you're doing it wrong! Righty-tidey, lefty-losey! Not lefty-tidey mess it up because you're a loser!"

    ZRX1200S, RGV250 VJ22, Skyteam T-Rex, Z50J1 '78, XV250 Virago

    Comment


    • #3
      Originally posted by Diggs View Post
      I had a DB Killer for the Tonelli that made a fairly big difference, but I found I never bothered using it as I was always WAY less noisy than any of the Harleys with straightshots.

      The only people I have ever heard getting done for noise are either ridiculously loud, or getting pulled for something else. Never heard of a Monkey being pulled for noise, only larger bikes. Then again it all depends on your local policing.
      Not worried about policing. I had a Duke with sports pipes and passed many traffic stops without any problem (although they invariably turned to look). I ride around some quiet country backroads and it is a social consideration. One person's sweet exhaust note is another's noise nuisance. It is just a personal choice. Also - I like to go on 2 - 3 hour fun rides and too loud an exhaust slightly loses its charm after an hour or two.

      Comment


      • #4
        Good thinking, if only ALL bikers thought this way.
        Rigby "No dude, you're doing it wrong! Righty-tidey, lefty-losey! Not lefty-tidey mess it up because you're a loser!"

        ZRX1200S, RGV250 VJ22, Skyteam T-Rex, Z50J1 '78, XV250 Virago

        Comment


        • #5
          As a bit of a fossil (68) with 12 road bikes over more than half-a-century of riding, I have an attitude which is geared towards survival. I have been hit twice in 50 years of riding and not fallen off a bike on the road (I came off on a race track - but I don't count this as I had been in hospital the previous week with a bite from a red-bellied black snake). While not an authority on anything I do have an opinion based on my own experience - which may not be relevant to others. One is straight visibility - so bright colours are useful. Another is awareness when out of sight. An exhaust which alerts tintops to your presence when in a blind spot (unless you have a transporter like Star Trek you have pass through a blind-spot in multi-lane traffic) is useful. Of course, a loudish exhaust won't protect you from being T-boned by someone running a red light. For that you have to have an attitude that you trust no-one and check left-and-right before moving off. Too loud an exhaust allows tintops to care less about your well-being as you get classed as a grub. I have found that a louder exhaust than standard discourages tail-gaters - possibly because an exhaust note which rattles the loose change in the ashtray invades the personal space of their tin-top safety cage. Another aspect to safe riding is, frankly, a level of perceived threat. When riding in heavy traffic (which I no longer do) an unstated, but implied, threat is the most effective. In many years of riding to Tech I found the best deterrent to being cut-off or leaned on in traffic was a big chain with a big padlock strapped over the shoulder. The 'chain' was one of those plastic chains in grey from a hardware store which was light but indistinguishable from the real thing. The implied threat part was the chain is ostensibly for locking up the bike for security reason, but the chunkiness of the chain and padlock seemed to have an effect. You might think this is all BS (fair enough - I probably would think the same if the positions were reversed), but I did a lot of A-B testing and there was a definite correlation between chain vs no-chain.

          So, for me, the loudness of the exhaust is a happy medium of personal pleasure, social awareness and safety.

          BTW - while I think the slash-pipe brigade are overall not helping bike-riders, I do note that while they are attracting the attention of the boys in blue, my non-standard exhaust is quiet by comparison and so not as likely to be a target of interest.

          Always good to try and find the silver lining...

          Comment


          • #6
            My Grom is fitted with the same Yoshimura exhaust without the dB killer fitted, and my 18 year old on P plates loves it like this.
            I think he’s crazy because of the attention it may draw to him and his activities, but you can’t put old heads on young shoulders.
            I’m big enough and ugly enough to fight my own battles with the powers that be, so I don’t worry about what might happen, but for a young fella life can be much crueller when you are not conformist.

            Comment


            • #7
              I agree , my bike is a little on the loud side but cars know your there or coming up beside them.

              Comment

              Working...
              X