A curiosity question: Three neighbors have Harley motorcycles (no clue what models) that produce dramatic differences in sound loudness. One, very big model, motors in and out of the neighborhood very quietly. One makes moderate noise. One rattles the windows although it seems like he guns the throttle to deliberately annoy neighbors. So, aside from gunning the engine, why are some bikes quiet and some very loud?
Harley’s come from the factory with a muffler. But most take the baffles out the second they arrive.
some CARS louder than others too.
and JUST like cars, the bikes also have a choice of exhaust options as well as accessory change-outs.
Nearly every Harley owner does the very same first modification. Change the exhaust to a much louder one. Their rational; they want cars to HEAR them coming. Actually, they want EVERYone to hear them coming to see they are riding a Harley Davidson motorcycle.
I very rarely see a Harley without loud pipes. Many H-D clones owners don’t do this. Victory, Honda Shadows, ect. They look like Harleys to the untrained eye so you could mistake them for a quiet Harley.
They second modification used to be a carburetor jet kit to remove the flat spot emission settings put in their bikes but they are all fuel injected now, so that isn’t needed.
What Mike said. The first thing most Harley riders do is swap out the exhaust/mufflers. Some for ‘medium’, some for ‘LOUD’. And many of the custom Harleys look like they have straight pipes, no muffler at all.
Many states don’t inspect motorcycles at all, and those that do it is a safety inspection. There are no emissions testing for motorcycles therefore the exhaust can be modified at the will of the owner.
Many bike owners do modify the exhaust for either more power or more noise. Harley owners seem to like a “straight pipe” sound which allows the full rich very loud exhaust note that can disrupt a quiet neighborhood.
Ah, thank you. I assumed it was the exhaust system but didn’t know in what way. As to clones, now I shall have to discreetly watch and see if I can espy the brand mark. 
Many Harley owners like the noise so the exhaust system gets gutted or changed. Many do this to gain attention while “profiling”; a term bikers use which means an ego boost to look cool for the peasants around them…
There’s also a performance factor involved (and the numbers are not set in stone) but an intake and exhaust change on a Harley can pick up about 15 extra horsepower.
Harleys have enough grunt anyway so to me anyway that extra bump is not necessary.
What’s a bit humorous(?) is that several people on the west side of town here have written letters to the editor about motorcycles with loud exhausts and wanting the city to do something about it.
These same people live under the flight pattern near the air base and listen to howling turboprop T-6s on one runway and T-38 jet trainers under full afterburner all day long on the outer runway and sometimes into late night with whistling T-1s in the middle runway…
<b> intake and exhaust change on a Harley can pick up about 15 extra horsepower</b>
Sorry to say Harley are still overweight, underpowered lumps even with 15 extra Hp compared to any other motorcycle.
Worked a project that had me riding a 735 lb H-D Road Glide most of the summer. I used to crack the throttle full-on pulling away. Doing that on my own, smaller displacement, 605 lb, Japanese touring bike, resulted in a wheelie. It had more power than I needed and less than many bikes but the HD was slooooow by comparison.
If ya can’t go fast, make noise!
Are there no laws to protect us innocent (usually) bystanders from this noise??
I’d say that if there are 100 cars and one motorcycle, the motorcycle makes more noise than the 100 cars.
I remember one occasion when I was eating at an outside table at a restaurant on Newbury st, and 3 motorcycles were parked on the street with their exhausts pointing at the tables, and they sat there running their engines and surrounding the diners with noise and exhaust fumes. When I asked them to move on, they just sat there and revved their engines.
the noise level of harleys seems to be in direct proportion to the size of the rider, in my casual survey…
perhaps in proportion to the size of their egos.
You mean like fatboy rides fatboy with straight pipes? Now I don’t mind the noise too much except for the unnecessary vroom vroom at stoplights etc., an aggravation it can be, but more boom boom base cars rattle my windows than Harleys, there are now these motorized bicycles that zoom faster than the speed limit and are surprisingly loud and whiney sounding. Reminds me of a group called los mosquitoes (the name on their jackets) on 175 or 250cc bikes that attempted to lock a bud and I on our english motorcycles, I think because my long blond curly hair flowing in the wind made them think I was a female. We got up to 90 plus mph and they could not keep up.
Wont those things idle?,why do you have to keep gunning them? I see one coming I roll up my windows,I cant stand the noise or smell,but I guess old boys,need loud toys.
Maybe the noise level is inverse to the drivers IQ level. And 50 years ago the 1200cc HDs couldn’t match the 650cc British bikes. Of course HD drivers mustn’t allow the public to overlook the odd firing blat-blat----blat-blat----blat-blat exhaust note indicating the antiquated design of the bottom end. I owned 2 HDs long ago and they were tough machines but Japan has made then third class rides these days. It’s all about image though.
Wont those things idle?,why do you have to keep gunning them?
Has nothing to do with keeping them running (most of the time), everything to do with showing off. Modern Harleys run great.
I thought about buying a Hardly Davidson once, but I decided I couldn’t afford all those black T-shirts.
Size of the rider’s what @Crusty_XII?
Just caught motorized bike on video, gotta love it, NOT
I heartily agree that those verdammt boom base stereos in cars are what I loath. And that is the polite version of what I think of them.
@Barkydog, your motorized bike had a 2 stroke engine like a chainsaw. Very annoying without a proper muffler. And I don’t understand why more riders aren’t ticketed for many infractions and the racket isn’t quite at the top of the list. I have seen crotch rockets passing cars at 50+ mph on the rear wheel.