There use to be a adjustment screw.

 

I'd like to adjust it to sound more "mean" and not so much as a little foreign car.

 

I can't remember the last time I saw a horn with an adjusting screw. And that was on a car I had many, many years ago. Maybe they stopped making them that way. Even so, it probably wouldn't make a whole lot of difference in volume, it just kinda changed the way it sounded.

 

It's easier (if not cheaper) to simply change it out for a more powerful sound - that's what I did.

The horn on my 2009 Sportster sounded like a sick canary, so I replaced it with a twin trumpet air horn. A much more satisfying sound and a sound that actually has the ability to alert semi-comatose unaware drivers to my presence. Much better, particularly approaching intersections. I cover the brake and cover the horn - preferably I won't need either one, simply passing through with a nod and a smile.

Ride Safe - Ride Smart

"He Who Lives In Joy Does His Creator's Will"
The Baal Shem Tov, Founder of Chasidic Judaism... ca. 1750's

 

Sorry I think air horns are made for trucks and trains.

 

If you do end up looking for a new horn the Wolo Bad Boy air horn might work for you. It's small so I mounted one on the tab between my frame down tubes.

 

Yes, it is on the back side, you will need to remove the horn from the bell. A lot of times when it is out of adjustment it will sound like a sick calf.

I have also found when the horn sounds sick (muffled) that the switch needs cleaned, I use DeOxit (good quality contact cleaner) to clean the corrosion that can form in the switch (may only be visible as a white residue) and then not send sufficient voltage to the horn thus making it sound very muffled. Spray in the cleaner then work the switch several times. You may need to remove the housing and switch cover to get at the actual contact.

If you want you can check the horn by direct contact to the battery.

 

I've also found that a weak sounding horn can be caused by a loose rubber mount.