Posted on September 30, 2025 by Michael Le Pard
Section Six ¾: The Engine Wars – How Loud Do You Want Your Motorcycle To Be?
So, how LOUD do you want your motorcycle to be? Do you want to wake up the neighbors, draw attention, or stealthily cruise around town? Many riders don’t think about this until after they buy their bike.
Legally, you can make your motorcycle as quiet as you like, but go too far the other way (LOUD) and you could end up with fines.
The Science of Sound
- Decibels (dB): Loudness is measured logarithmically. A 10 dB increase is perceived as roughly twice as loud.
- Frequency: Low-frequency sounds (like a Harley’s rumble) travel farther and penetrate walls more easily than high-pitched sportbike screams.
- Resonance: Exhaust pipes act like tuned instruments. Length, diameter, and baffle design shape the tone.
Motorcycle sound is more than noise, it’s identity, safety, and sometimes controversy. Understanding what makes a bike loud helps you choose the right ride for your lifestyle.
Engine Factors That Influence Loudness
- Displacement (cc): Bigger engines push more air, creating more sound energy.
- Cylinder Count: Fewer cylinders = louder pulses. A big single or twin is louder than a four of the same size.
- Firing Order: The rhythm of combustion affects tone. A 90° V-Twin has a syncopated “potato-potato” sound, while an inline-four screams smoothly.
- RPM Range: High-revving engines produce higher-pitched, continuous sound. Low-revving engines produce deeper, thumping notes.
Exhaust System Factors
- Baffles: Internal plates that disrupt airflow and absorb sound. Removing them increases volume dramatically.
- dB Killers: Removable inserts that reduce noise.
- Aftermarket vs. OEM: Stock exhausts are designed to meet legal limits. Aftermarket systems often prioritize performance or sound.
- Condition: Rusted or damaged exhausts lose baffling and become louder.
Tip: Very few aftermarket exhausts are quieter than stock. If you want quiet, keep your OEM system in good shape.
What Makes a Motorcycle Loud?
Engine Factors:
- A. Size of Engine: Bigger engines are louder.
- B. Number of Cylinders: Fewer cylinders = louder.
Exhaust Factors:
- C. Construction & Flow: More restriction = quieter. Free-flowing = louder.
- D. Purpose: Racing exhausts are loud, OEM touring exhausts are quiet.
Formula Recap:
Quiet Bike = Small engine + more cylinders + stock exhaust.
Loud Bike = Big engine + fewer cylinders + aftermarket exhaust.
Living With Loudness
Loud bikes turn heads, but they also turn neighbors into enemies. A 6 a.m. cold start with open pipes might feel glorious to you, but Mrs. Johnson next door may not agree. On long trips, constant droning can wear you down, and in group rides, the loudest bike often drowns out everyone else’s fun.
- Pros of Loud: Attention-grabbing, visceral, makes you feel connected to the machine.
- Cons of Loud: Fatiguing on long rides, potential fines, community complaints.
- Pros of Quiet: Comfortable for touring, stealthy in neighborhoods, less rider fatigue.
- Cons of Quiet: Less “character,” some riders feel invisible in traffic.
The sweet spot? A bike that sounds alive without being obnoxious. Think of it like music volume: you want to enjoy the song, not blow out the speakers.
Real-World Examples
- Harley-Davidson Fat Bob 114: Big-displacement V-Twin, naturally loud, deep rumble.
- KTM 1290 Super Duke R: High-performance V-Twin, aggressive but tuned for racing.
- Honda CB750 Inline-4: Smooth, high-revving, less loud but piercing at redline.
- BMW R18 Boxer Twin: Deep, balanced tone, wide cylinder layout adds resonance.
Conclusion
Motorcycle loudness is a blend of engineering, culture, and personal preference. Whether you want stealth or thunder, the key is understanding how engine size, cylinder count, and exhaust design interact. With this knowledge, you can make an informed choice that fits your riding style, respects your community, and keeps you on the right side of the law.
Special thanks to Kim Murray in Tampa, FL for inspiring this section.
