What is meant by "harmonics"?

[rewindstuff]

I think I have an idea, but how would you detect it and when? Engine under load? Idle and neutral revving? What sounds should I be one the lookout for? Anybody got a definition?

 

[crazypj]

It's when a bunch of different vibrations get in sync and cause a problem.
Things tend to break with harmonic vibration.
When intake and exhaust are tuned to correct harmonic frequencies you get a nice power boost

 

[rewindstuff]

that seems so abstract to me. like, how would you know what frequencies are produced by my rockers? or my counterbalance shaft? or any engine component? and how do you change it?

 

[DuckHunterJon]

Tbe correct way would be to spend several years getting a mechanical engineering degree, with a minor in vibration analysis. Then, instrument the bike/engine with several accelerometers and perform a complete modal analysis, both under static and dynamic load.

The much easier way is to say fuck it and go riding.



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[DuckHunterJon]

Just joshin with ya. To answer your question, there are two ways to change resonant frequencies. Either lessen the amplitude, or shift the frequency off the harmonic. If you want to get deeper than that, I'd be happy to discuss when I can type on a real keyboard instead of this phone.

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[crazypj]

Don't worry about it, there isn't a lot you can do without spending a bunch of cash and a bunch of time
Spend time riding, it's fun ;D