The Prophet

How about some discussions on exhaust systems? Seems to me:

1.) I've yet to see convincing - although I would admit that there are almost always benefits to an aftermarket sytem - data or technical proof that Brand "X" exhaust is any better than Brand "Y".
2.) In many, many forums and threads on the subject, the vast majority talk about the "great sound" and then mention in passing that the performance of the bike was "unbelievably improved", yet no 1/4 mile, lap time, or other convincing data is shown.
3.) A dyno chart showing a 2 HP improvement at 9500 RPM, is not exactly convincing, nor a justifiable reason to spend $1000 bucks.
4.) Manufacturers Websites sometimes claim a lot of things, but offer no guarantee, and the suspect "Dyno" charts are unconvincing and subject to discerning examination as many other mod's have been done to the test bikes.

All that for starters, add the countless "tribal knowledge" and downright incorrect information handed out by the countless "Internet Mechanics" and "Internet Bike Experts" out there, and it's a total mess.

Who can provide convincing, real, proven,unbiased recommendations on a good, solid, quiet, reliable, and affordable to the masses Exhaust brand for motorcycles?

Rules:

No "straight Pipes"
No "shorty Pipes"
Remember, legislation for quieter exhausts is definitely on the way, thanks to our "Loud pipes save lives" buddies, so there is little sense in making more noise anymore - if there ever was!
Who has the best performance increasing , quiet, proven, affordable silencers around?

Bob

__________________

• A good traveler has no fixed plans, and is not intent on arriving. ~Lao Tzu
• Wisdom is what's left after we've run out of personal opinions.
• Saying what we think gives us a wider conversational range than saying what we know. ~ Cullen Hightower

Speedtrip

I believe the best case for an after market exhaust is weight savings. The Arrow full system for the Triumph Speed Triple shaved more than 20 pounds. That is a lot of weight especially considering how high the Triple carried the weight of it's stock cans. The Arrow also relocated the can down low behind the rearset.

Affordable is a whole other can of worms, there are plenty of Chinese made tin cans on flebay for a hundred bucks. But very few quality made pipes for what I would call affordable.

__________________
-Shaun-

The Prophet

Excellent, excellent point. Somewhere there is a "Rule of Thumb" about saving one pound is equal to adding "x" horsepower.

Why is it that stock offers seem to be so heavy. Example on the Triumph Bonneville - these silencers admittedly are beautiful, the chrome is deep and flawless, but why so heavy? Must be the numerous interior series of metal baffles and sound deadoning sections mandated by the "quiet police", and reluctantly complied with by the OEM design team. One could argue though, that these would last for many, many years. Look for future silencers by the OEM folks to be increasingly heavier and quieter, aggravated every time a "loud pipes" newbie blips his throttle.

You would think it would be straight-forward, as in the Stock silencer for "such and such" a bike flows "x" cfm at the following rpm's, and "Our Silencer", flows this much more. Why have we never seen someone place a series of silencers on a Flowbench? Why not a choice of length's? A choice of diameters? A choice of reverse cone end pieces, with harmonic pulsation wave performance data included?

Instead, the aftermarket manufacturers emphasize the "sound" and ... "tremendous" power gains(if 1 to 2 horsepower is "tremendous").

Traditionally, short, large diameter pipes are good for ultra high RPM power, and additional top speed, but steal it from the bottom end, as seen in a lack of low end and mid-range torque.

On the other hand, long, thinner diameter pipes provide better low end torque, but sacrifice top end horsepower.

Many riders don't realise that required CFM flow starts out small, and increases as RPM increases. That said, the stock silencer is ok until you reach a certain high rpm. The stock silencer is also carefully tuned to pulsate at exactly the correct moment to work with the intake in improved cylinder filling. Messing with it removes this feature, just so folks know. This is why the actual improvement usually only turns out to be a few HP on a dyno, at a near redline rpm. See the December 2009 issue of "Sport Rider" for a wierd example. The Dyno sheet shows a 1.5 HP increase at 10,250 RPM, but the articles author says it results in an "obvious" improvement... OK!

As you note, Shaun, it very likely has more to do with the weight savings, not the 1.5 HP at redline. Dyno's don't see the weight loss advantage, but we feel it with our finely tuned SOTP's performance indicators, and more importantly, Stopwatches.

As in most cases, it becomes a compromise. Wouldn't in be nice if someone built a silencer with adjustable length tubing, and a reverse cone end piece that could be adjustable and/or optional. This way, lap times could be recorded under various scenario's, until a satisfactory powerband curve is achieved. The buyer could then adjust pipe diameter, length, and reverse pulsation to result in a smooth, predictable, improved torque curve, placing the powerband peak wherever it returned the best performance.

Pricewise, zero is best - as in a home performed "baffle-ectomy", but I would suggest something in the $250 to $450 dollar range might be reasonable if the quality of build and materials were higher end.

"Sound" is of course debatable forever, and an extremely personal choice. One man's treasure is another man's garbage as they say. Me? I prefer quiet, as I take long rides - as in 2 to 6 hours on any given day. Listening to the exhaust blatting away behind my ear for hours on end would not be good for long term hearing, would aggravate folks around me, and would be tiring after a few minutes. Is this maybe why it seems most "Loud Pipes" newbie riders stop at every bar, or every 5 miles, whichever comes first?

At any rate, anyone know of a knowledgable tuner that works with the individual to adjust and tune a good quality set of silencers and pipe combinations to result in an improved powerband?

Thanks,

Bob

__________________

• A good traveler has no fixed plans, and is not intent on arriving. ~Lao Tzu
• Wisdom is what's left after we've run out of personal opinions.
• Saying what we think gives us a wider conversational range than saying what we know. ~ Cullen Hightower

The Prophet

Here is an extremely interesting, very well written muse on motorcycle exhausts.

RB Racing LSR 2-1 Exhaust Technology

Granted, it pertains directly to Harley Davidson models, but the specific technology discussed, and the pulse wave concept rings (no pun intended) true for all bike exhausts.

Well worth the time and effort to read through it and ponder, as it presents an excellent study, as well as dispelling many, many time honored myths surrounding the exhaust and silencer systems on our bikes.

Ride Safe (and quiet!),

Bob

__________________

• A good traveler has no fixed plans, and is not intent on arriving. ~Lao Tzu
• Wisdom is what's left after we've run out of personal opinions.
• Saying what we think gives us a wider conversational range than saying what we know. ~ Cullen Hightower

The Prophet

Here are a few more articles on aftermarket Motorcycle Exhaust comparisons.

http://www.motorcyclecruiser.com/accessoriesandgear/pipecomparo97/index.html

http://www.motorcyclecruiser.com/accessoriesandgear/exhaust_pipe_comparison/index.html

Read extremely thoroughly before drawing any conclusions...

1.) Realise that in these test comparisons, re-jetting alone from stock provided 1.9 HP, so the end results of +3.1 HP or so gained are actually 1.2 HP gained (3.1-1.9). 1.2 HP gained at max RPM for + $700.00 is... debatable?

Pipe Jetting

2.) Any of these exhausts that are over say 95dB should be quickly discarded, as new legislation coming your way soon will make them officially illegal. Additionally, only those who use their bikes to travel 2 miles to the local biker bar have these straight, loud, obnoxious pipes. If you have ever tried to make a reasonably long trip with pipes like this, they are very tiring, and very tedious after twenty miles or so. It is no surprise that most loud pipes are on bikes that you would look at and refuse to take on a long (more than 50 mile) trip, as they are not ergonomically designed for comfort, or long range riding.

3.) In the end, Speedtrip nailed it, the real advantage of aftermarket pipes is the weight saving, especially with modern, high-end sportbike stock offers. Ever increasing EPA and local noise (thanks loud pipe morons!) legislations have forced the designers to focus more and more on sound restriction, and this CAN be done without excessive back pressure, but it gets expensive... and heavy. Note how large stock cans are getting - this is why.

4.) Money and effort formerly spent on aftermarket exhausts is probably better spent now-a-days on cylinder head flow-work, vlavetrain improvements, and/or ignition and fuel computer re-mapping.

In closing, it wil be interesting to see how damaging the past years of "Loud Pipes" will effect future opportunities of tuning our bikes to the best performance levels. It CAN be done quietly, and legally, as noted prior, but it becomes expensive, and adds weight, unless rare metals and/or expensive carbon fiber derivitives are placed into the equation, adding yet more costs.

Lastly, always remember, it is the averaged Torque and Horsepower results spread evenly over the practical RPM Powerband that makes street bikes perform better, and increases the enjoyment and performance of everyday street riding, not the "peak" HP readings, good primarily for Dyno Racing on the "Virtual" internet, having nothing to do with reality.


Ride Safe!

Bob

__________________

• A good traveler has no fixed plans, and is not intent on arriving. ~Lao Tzu
• Wisdom is what's left after we've run out of personal opinions.
• Saying what we think gives us a wider conversational range than saying what we know. ~ Cullen Hightower

The Prophet

An excellent, thought provoking thesis on "aftermarket exhausts... and re-jetting"... or not.

Interesting.

Pipe Jetting


Ride safe (and efficiently)!

Bob

__________________

• A good traveler has no fixed plans, and is not intent on arriving. ~Lao Tzu
• Wisdom is what's left after we've run out of personal opinions.
• Saying what we think gives us a wider conversational range than saying what we know. ~ Cullen Hightower

motowebmaster

The only bike I ever replaced the exhaust on was my very first machine, a Triumph Adventurer. It made for some interesting pops and did make the machine a bit more perky on the road; but would agree that it just increased the fun factor.

For sportbikes with an image, an aftermarket system can boost the looks, but I wonder if it makes the motorcycle safer in the hills when weight is taken from the rear. We want to put as much force as possible on the front wheel, so taking a hypothetical twenty pounds off the rear concerns me when where riding some of our bumpy roads.

When my VFR was new, there were already videos of my model year being used as subjects of exhaust upgrades. One video I remember from France took my exact bike originally with it's stock exhaust, then without any mufflers, and then with the aftermarket cans. It did improve sound, which is what the video demonstrated well.

The irony these days is that I ride around in a good helmet that flows air well, wearing earplugs suited for track use. I can hear some sounds, but not others. My bikes sounds are more like vibrations, than actual exhaust sounds. In other words, my engine is more prominent than what my stock exhaust is doing.

Now if I ever could afford a BMC Bobber and had the time to tool around town ...

__________________
Shawn - MotoWebmaster
Motorcycles International
My Photos

The Prophet

Here's some solid information on the SAE #J2825 Standard for sound testing motorcycle exhausts:

Motorcycle Industry Council

Note the position and location of the sound meter, and the decible levels allowed.

These seem very reasonable to me. Note that a Stock Triumph motorcycle in the 1960's for example, tested in the mid 90's decible range. That said, a bike can still sound like a bike, yet not be offensive and/or irritating to others.

Ride Safe!

Bob

__________________

• A good traveler has no fixed plans, and is not intent on arriving. ~Lao Tzu
• Wisdom is what's left after we've run out of personal opinions.
• Saying what we think gives us a wider conversational range than saying what we know. ~ Cullen Hightower

The Prophet

Another decent article on exhausts and mufflers...

Undercover - Taking a Look into Muffler Technology: Tomorrow's Technician

This pertains to automobiles, but the technology and content is extremely similar for bikes.

Ride Safe!

Bob

__________________

• A good traveler has no fixed plans, and is not intent on arriving. ~Lao Tzu
• Wisdom is what's left after we've run out of personal opinions.
• Saying what we think gives us a wider conversational range than saying what we know. ~ Cullen Hightower

The Prophet

In keeping with the concept of pure objectivity, here's another good article on precisely measuring Exhaust Backpressure:

Exhaust Backpressure

Simply place a guage in the 02 sensor port (or other) and obtain a reading. See text for further explanation. I would venture that many may be surprised at how good some of the stock exhausts are, and how much is paid by "modders" for not much improvement... backpressure-wise. Paying a lot of money for something very often accelerates and enhances the "placebo effect", and the additional noise contributes to the percieved effect as well.

As stated prior, the improvement is more often in the weight savings, but be cognicent of the quality of finish, and the expected lifespan of those pricey after-market exhausts.

Your choice of course, as always, just some tidbits to chew on.

Ride Safe (and quiet!)


Bob

__________________

• A good traveler has no fixed plans, and is not intent on arriving. ~Lao Tzu
• Wisdom is what's left after we've run out of personal opinions.
• Saying what we think gives us a wider conversational range than saying what we know. ~ Cullen Hightower