-That may be true to a certain extent for full automotive type exhaust systems (not just “mufflers”, an individual component) or even exhaust systems for motorcycles (though it’s been my experience with 2-stoke bikes and snowmachines that the stock pipes are very good, and aftermarket units merely move the HP/torque peak up or down the RPM band) but for the “straight pipes” on a Harley? Please.
A straight pipe- the point of the OP, by the way, as any sort of baffling at all tends to reduce the noise considerably- loses most of the antireversion effects and almost negates any cylinder scavenging effects, leading to conditions like spent-gas contamination of the incoming charge.
Top-Fuel racers are about the last to use “straight pipes”, but these are supercharged engines running nitromethane- practically an explosive. Pro-Stock classes and the majority of the bracketracer classes show racers using full exhausts including mufflers specifically designed for the RPM ranges. Mainly because they’ve found that they can gain X fraction of a second and X extra couple of horsepower with proper exhaust tuning.
So yes, in a way you’re right- a well designed exhaust system can indeed add a small percentage of horsepower over the stock system. (Though often at the expense of power elsewhere in the band.) But straight pipes aren’t an “system”- They’re rarely tuned to any degree at all. They’re typically jsut formed, cut, polished and chromed so they look good, who cares how much power the provide.
long time motorcycle rider here and a long time member of the motorcycle industry (on a retail level, british bikes mostly).
the “loud pipes save lives” argument has been shown to be bs about 1,000 times, try asking the ama (www.amadirectlink.org).
motorcycle exhaust systems are designed by engineers to provide a reasonable spread of power AND to control noise so that the thing meets EPA approval and can be sold in the country.
in all fairness, changing exhaust (and rejetting the carbs) is a relatively cheap way to extract more power (you get a lot of bang for your buck), BUT there is a limit, engines are designed to run with a measured amount of back pressure in the exhaust and if you do away with said pressure the performance, mileage and longevity of your engine suffer.
in my personal dictionary motorcycles are fast, handle well and stop quickly, harley’s do not do ANY of the above, they are “butt jewelry”, most riders are in the “look how cool i am” club (if you don’t believe me look at their back tires (if they are “worn square” the bike never goes around corners, we call these “chicken strips”) and/or look at the odometer (a 5 year old bike with 3,800 miles, you do the math).
if these moron’s don’t change themselves, the government is gonna come down on ALL motorcycles, so these idiots are risking MY rights.
from the link above,
see “protecting your right to ride”
Consumer Modifications
The EPA recognizes the tendency of owners to modify their motorcycles to enhance performance and style. It cited the Clean Air Act section 203(a) as the legal authority that makes it illegal “for any person to remove or render inoperative any device or element of design installed on or in a motor vehicle or motor vehicle engine in compliance with regulations under this title…after such sale and delivery to the ultimate purchaser…”
The EPA stated: “We use the term “tampering” to refer specifically to actions that are illegal under the Clean Air Act section 203; the term, and the prohibition, do not apply generally to the wide range of actions that a motorcycle enthusiast can take to personalize his or her motorcycle, but only to actions that remove or disable emission control devices or cause the emissions to exceed the standards.” The EPA further stated: “Owners would still be free generally to customize their motorcycles in any way, as long as they do not disable emission controls or cause the motorcycle to exceed the emission standards.”
I can appreciate a loud bike, even if I understand that others hate them. But if I hear a shitload of noise, the bike producing it better be fucking fast. A screaming Ninja will get my thumbs-up any day of the week, but a friggin’ Harley that shatters my eardrums through my ful-face helmet?
No way.
I’m just glad my stock Yamaha Diversion can easily accelerate away from those idiots.
No offense to any stock-Harley riders. They do have their appeal. But these loud pipes aren’t part of it.
Fine by me. Second to assholes on motorcycles who think its “cool” to drown out all conversation within a twenty mile radius with those obnoxious should-be-illegal machines are assholes who play their hideous music so loud in a convertible or with their windows rolled down that they pull up next to me and I can’t hear my OWN radio, in my car, with my windows rolled UP. That should be illegal. I should be able to shoot those people.
If you want to listen to music loud in a car, roll your God damn windows up. If you’re stupid enough to ride a motorcycle, have the basic decency not to make so much fucking noise that it bothers those around you.