The Sound of Engine Revs

[KingKong]

A bit of a strange post, but please bear with me.

I have noticed that sports bikes make various different sounds when they are revved. Was riding with another 600 last night and as we departed each other's company for our separate turn offs, the chap on the R6 revved his engine as a farewell bid.

Well, here's what it sounds like - go to 2m 53s, please:

https://www.youtube.com/watch?v=TTf-rNte5Eo

How does one make their revs sound like that, does it have something to do with some sort of customised component?
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Kwak 636 (2005)

Past - 2016 Ninja 300 (dark grey); K4 GSXR 600 (sexy yellow); 2002 CBR600FS; 2004 GSXR 1000; 2006 Kwak 636; 2005 Yamaha XVS 1100 Dragstar (facepalm); 2005 Kwak 636; 2011 Yamaha R125.

[nowhere.elysium]

What, bouncing it off the limiter?
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'10 SV650SF, '83 GS650GT (it lives!), Questionable DIY dash project, 3D Printer project, Lasercutter project

[KingKong]

[lihp]

Engine noise comes down to only a few parameters.

Engine capacity, engine configuration, and system. Largely though the system only really affects the volume of the engine, configuration and size are responsible for the tone.

[lihp]

Engine noise comes down to only a few parameters.

Engine capacity, engine configuration, and system. Largely though the system only really affects the volume of the engine, configuration and size are responsible for the tone.

[KingKong]

[lihp]

R6 is an inline 4 so take your guess

[plugger147]

It's being rev'd up to hit the limiter like so...

https://m.youtube.com/index?desktop_uri=%2F&gl=US#/watch?v=rRcs856CT_w

Nothing special added, it's like a safety device to stop you over reving...
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Tristan the wrote: just whipped off my trousers to find a big bruise on my arse, caused by matt rear ending me...

[KingKong]

[Walloper]

Most of wot you hear is from the exhaust.
Fit a different muffler and you get a vastly different sound.

Engine gas flow has an effect.
Engine timing has an effect but Exhaust Note FTW.
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W-ireless A-rtificial L-ifeform L-imited to O-bservation P-eacekeeping and E-fficient R-epair

[plugger147]

Sorry, that was a mobile link try this one...
https://www.youtube.com/watch?v=rRcs856CT_w
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Tristan the wrote: just whipped off my trousers to find a big bruise on my arse, caused by matt rear ending me...

[Paulington]

As has been said it's just bouncing off the limiter. All this means is that when it hits the rev limiter (around the redline) the ignition gets cut/fuel stops or anything like that momentarily to stop the engine revving over that pre-determined number.

A limiter is there just for the safety of the engine as the manufacturer has decided that revving over that number could heavily damage the engine. Almost all modern bikes have a rev limiter, same with cars.

No detriment to having one. To make that noise on a bike with a rev limiter just hold the clutch in and pin the throttle back. It will rev, hit the limiter and just keep 'bouncing' off of it until you let the throttle go.

Cheers!
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"Four wheels move the body, two wheels move the soul."
Current Vehicles: '89 Kawasaki KDX200, '99 Yamaha XV535, '00 Honda ST1100 Pan-European, '08 Suzuki GSX-R1000, '08 Mitsubishi Lancer GS4 2.0 TDCi, '15 BMW 1 Series 116d Sport Turbo.
CBT: 27/08/08. Theory: 04/09/09. Module 1: 16/09/09. Module 2: 01/10/09.

[KingKong]

Aha That makes a lot of sense now

Thank you very much for clarifying that for me Paulington; Plugger 147; and nowhere.elysium


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Kwak 636 (2005)

Past - 2016 Ninja 300 (dark grey); K4 GSXR 600 (sexy yellow); 2002 CBR600FS; 2004 GSXR 1000; 2006 Kwak 636; 2005 Yamaha XVS 1100 Dragstar (facepalm); 2005 Kwak 636; 2011 Yamaha R125.

[Jim Mc]

Reving to 15k without any load can't be healthy for the engine.

[weasley]

[Walloper]

[sickpup]

[lihp]

An engine with no load on it, can rev beyond the limit due to the momentum and lack of load, the engine revs will drop down again, but it will over rev.

[Walloper]

[lihp]

Engines are not designed to be revved with no load though.

The revs pick up far far faster without a load, and the resolution often not quick enough to "catch" the revs before they over shoot the limiter.

It's common for cars to have 2 limiters, for in gear and not in gear, however, I'd be suprised if this has shifted over to bikes yet, and even then, it would only be on the newest of the models.

[Walloper]

[Dracon]

[L4Isoside]

[Walloper]

So what damaging forces at max No Load Speed are at work when the same speed is OK at Full Load?

I think there is a confusion in physics at large in this thread.

Engine RPM is limited by the various moving masses in the engine (and, to a degree, the amount/mixture/type of fuel burned during combustion.)
The masses are moving with MORE stored energy under load than at no load.
1000s of psi combustion gas pressure pushing against the load.

I do not see any reason for a manufacturer to fit limiters (Which I would call them as opposed to governors which not only control max speed but max power too. Vastly different things) for no load speeds unless only to meet emission tests where an idle mixture may produce more NOX etc. Or something more scientific.

Where the hell are the bcf chemists and fizzicysts when needed. Same as the police and taxes I guess.

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W-ireless A-rtificial L-ifeform L-imited to O-bservation P-eacekeeping and E-fficient R-epair

[weasley]

I have a degree in Chemistry and have worked in the field of engine oil product development and testing for 20 years. Does that count?
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