I have a question about sound levels. I've been debating this issue with my dad for a few days. Glamis convinced me that ANYWHERE, 4-strokes are louder than 2-strokes. In the dunes and with aftermarket exhaust, you can hear a 4-stroke for miles. After a 2-stroke dips behind a hill, you can barely hear it. My dad and I agree with this, but we disagree on which is louder when you are standing right next to them. At twenty feet away, I think that a 4-stroke with aftermarket exhaust will be louder than a 2-stroke. Put a Banshee with full FMF exhaust next to a 400EX with FMF Power Core IV exhaust, and the 400EX will be louder. That is my opinion and I would like people to let me know what they think.

 

Well, it all has to do with the frequencies involved.

The long wavelengths of the low frequencies generated by 4 strokes have an easier time passing thru and around objects than the higher frequencies generated by 2 strokes.

Just try cranking your home stereo up a little, then go in an adjecent room and close the door. Notice that the low frequencies you can still hear fairly well, but the highs you cannot.

BUT.... The frequencies that a 2 stroke produce fall closer to the range that the human ear is most sensitive.

So.... I guess it depends on the circumstances involved.

 

Check out this site,
http://oohva.org
and look at the "Sound Issues" section.

At the bottom of the page, it's got the dB levels for most bikes.

I agree with you though, 4 stroke sound travels further.

 

Nothing scientific about this response, Mike, although the comment on this thread about the penetrating power of the low frequencies makes sense (listening to the "boom-boxes with wheels" on the street, one hears the bass beat LONG before anything else).

Just this: Listening to a representative sample of the 6000 ATV's at the Cochranton, PA, Poker Run, and a couple of thousand at two Tours de Forest, the nastiest, most irritating, deafening, annoying sounds I heard came from (envelope, please!) TWO-STROKES!

Eric Baatz and I couldn't hear ourselves think for a mile approach and a mile departure of a character on a two-stroke, as we rested alongside the "middle" loop.

Again, my subjective observations only.

Tree Farmer

 

Tree Farmer, that's interesting that you think 2-strokes are louder, or "annoying." And with the car stereo situation, you always hear the bass first. Personally, I have not heard one annoying quad. Sure, lots have been way too loud but not annoying. And one more thing, I'm not saying I don't like the sound of 2-strokes, because I do. There is nothing like hearing a piped-Banshee shriek up a hill. In my opinion, I just think 4-strokes are louder and you can hear them from a further distance.

 

AS someone pointed out, it has to do with frequencies. As an amateur radio operator, I operate on UHF/VHF bands, which, are relatively short range frequencies dependant on repeaters to gain any distance. Conversely the "low bands" are what are used to transmit worldwide because of their ability to "bend" or skip over,around, or thru, objects or atmospheric conditions. That's why you hear 4 strokes over the other side of dunes. Also, that's why the riders of YZ400's sometimes play "head" games with 2 stroke riders in mx.They think an angry bull is on their back fender when they're actually a 1/2 lap behind.(:
Long answer to a short question.

 

I have heard plenty of annoying bikes/quads. There is a BIG difference between a good sounding 2stroke and one that sounds bad. Same goes for 4 strokes, cars, trucks, boats, etc....

Want to hear an excellent example of a bad sounding bike, pull your silencer completely off.

Listen to Hotshoe and keep in mind, even though on a unweighted dB meter a particular 4 stroke may be louder than a particular 2stroke, the human ear is not linear in response, and is more sensitive in the higher frequencies, peaking aroud 8KHz. So it may be perceived that the 2stroke is "more annoying" due to the fact that:
1), frequency is higher
2), you actually hear it louder when it is near

 

Personally,
I think a 4 stroke is much louder and obnoxious than a 2 stroke. At the dunes in Colorado, I can talk to a friend all day with 2 strokes buzzing around. One time a piped and built(not sure of the brand of pipe) 400 EX simply started its motor about 5 feet from us. We could not hold a conversasion until they left. It was too loud ( never thought Id see myself saying that!) What about watching MotoCross on TV? when the 4 stroke YZ 400 bike is running, it is much louder than the other 2 strokes. You can always tell when they get on the gas out of the corners.
A piped Banshee sound is matched by no other though!!!

RoostKing...

 

OK, I agree with the posts about the 4-stoke can be heard for miles. It can! I think most aftermarket 4-stroke pipes are very anoying. I hate the sound on my FMF LT250R. THe Banshee is indeed hte best sounding 2-stroke out there. I guess the sounds all depends on where you are. My 400EX can be heard far with the stock muffler when I ride in a small area. When a 2-stroke and 4-stroke aproch me, I heard the 4-stroke over the 2-stroke. The only time a 2-stroke is loud is when it is revin it out right in front of you.

 

I agree, the Banshee is the most awesome sounding quad ever built. I got to ride on for the first time Saturday and they sound even better while your riding them. No thumper ever sounded like that.

Worst sounding quad: My Blaster after I broke an exhause stud. It sounded like a never ending fart.

On the noise issue, at the Lorrettas MX this year, you could always tell a 4-stroke class from the noise. It is a lot louder than the 2-stroked. You could always carry on a fairly normal conversation over the 2-strokes, but when the thumpers were on the track, no way.