look twice!!! motorcycles are everywhere!!!

[RK-REX]

Interesting.

From an engineering perspective, sound == energy. So, the louder an engine is, the less efficient (without the use of a muffler, which does nothing but baffle the compression wave coming down the pipe to drop the amplitude and smooth out the sine wave)

Wouldn't you get more performance out of it by tuning the engine such that more energy is transmitted to the drive mechanism than wasted going down the pipe?

That said, I can understand how allowing the exhaust to escape unbaffled would improve that side of the performance equation. Less back pressure and all.

Here in Southern Scottsdale, we get a lot of the "weekend rider" crowd. They tend to be less polite about their motorcycling habits than the every-day bikers, I think.

You are correct on all counts. However, in order for most bikes to pass emissions laws, they are jetted very lean to reduce the output of all the bad stuff that melts the ice caps and such. The exhaust is tuned to get the most power from this lean mixture. Smaller diameter, heavier material pipes and a quiet(restrictive) muffler. This tuning is based upon the type of performance you want from the bike. Manufacturers go for all around power, which makes sense. The formula is based on the operating rpm of the engine or where it will see the most use. I forget what it is now, I have it at home, but it's something like LENGTH=250,000/.8 X rpm.

So in order to get the most power from a stock engine, which is just an big air pump, we increase the fuel intake, which requires increased air intake to maintain a correct air/fuel ratio. Normally in the form of a less restrictive air filter. Now that we've got the right ratio of air and fuel. The books say 14:1 is best, but the dyno test sheet always says that it's around 12 to 1 for best rear wheel horsepower. Anyway, now that we have determined the right amount of fuel/air that the engine needs, we have to evacuate the burnt gasses as quickly and efficiently as possible so that we can take in more air/fuel mixture. Now the larger, free flowing, light weight exhaust comes into play. A good titanium system can weigh as little as 15# where a stock pipe is around 40#. Again the length of the pipes are tuned to where you want the bike to perform. In all actuality it all has to be done at once, but you can estimate what you'll need, then fine tune the air/fuel once you've got the pipe on and are hooked up to a dyno with a exhaust gas analyzer.

I'm a torque junkie, I could care less about going 150 mph, I want to be the first to 70mph, so I normally try to find a stepped pipe that produces more low end power. For example, on the bike I ride most, a Kawasaki ZRX1200R, I run a pipe that goes from 4 pipes into two pipes, into one pipe then into the muffler.

I'm guessing with the exception of Caradoc, that just bored the heck out of everyone. LOL

Weekend warriors are bad news no matter what the event, sport, etc....

[Fearnest]

I'm guessing with the exception of Caradoc, that just bored the heck out of everyone. LOL

And me - that was great! Muitos obrigados, Rex!