Failed sound test w/ Q Pipe

Anyone know of a decent Quiet! system for my WR426. even an insert for the stock can that flows beter than the original insert. Ive failed two sound tests with a freshly packed FMF Q and the Powerbomb header. Help!

Check the TTR section and get yourself a stock exhaust plug from a TTR-250. It's a perfect fit and has a larger diameter then the stock WR plug. Works real nice.

What db rating are you getting when tested? I had my bike tested with the same setup and it came in at 95db. Eric

A vortip tests at about 90db +/- and costs about $60 to $100 depending upon where you buy it. I use one on my WR426 and the power feels slightly stronger down low, slightly less on top than totally uncorked. I'm a fairly aggresive rider and I like it.

This is very interesting....Isn't this the exact pipe that Bill Dart has been recommending as the pipe to get to be able to pass the new tougher sound checks in CA. ?

bigdrtrdr....never did respond with the results of the DB test....hmmmmmmmmmmmmmmmmmmmmmm.

Bonzai :)

Sorry I havent been back in a few days. Heres the way its been. Sunday 10/20 my 01 426 WR tested by Skagit M/C at the Ducks Delight poker run at 101db 4500 per the Motorcycle Industry council stationary sound test procedure. Needless to say they were fairley shocked. And so were the 20 or so other riders in line to be checked at that time. Since then I have been in contact with FMF "Doug Mueler" customer service Mgr. and his quote to me was "that bike with the Q and Power bomb header will on any given day pass or not pass, given many different circumstances. Nice! So anyway he is still sending me a new updated end cap and bulkhead so I will be up to current standards.

And as I posted months ago whe I first bought this system it was to loud and I sent It back to FMF. They redid somthing to quiet it down but I still wasnt happy so FMF sent me the PowerBomb header N/C. I cant say they FMF havent tried but we will see How it turn out. I will keep TT posted.

Eric (bigdrtrdr)

No one seems to understand that this is a very inexact science, sound testing. It is so subjective as to be utterly inconsistent. That's why standards such as these can be so unfair. A guy passes today, and can't tomorrow, despite all efforts and expense. Different methods, different testers, different meters, and ambient noise or echo are all factors that seem to have been ignored in all this. The architects of these laws claim calibration standards and all that jive, but it's all baloney if ALL the other variables aren't controlled. And they aren't. If the "standards" can't be applied fairly across all users, then they are not truly standards, are they?

In our society, a lack of fair standards is a good enough reason to allow dangerous criminals to go free. A lack of fair standards costs us millions of dollars in contracts awarded to minority firms and other contractors with special qualifications even though they may be high bidder. For the very same reasons, a lack of fair standards SHOULD disqualify an arbitrary sound law that unfairly discriminates against you and I in our favorite sport/activity. But somehow, it doesn't.

And it's not really the fault of FMF or Pro Circuit or White Brothers or Big Gun.

My 2 cents.


A consistantly attainable standard would be nice though..

Bonzai :)

Whoa, Dan!! It's not as bad as you say. The SAEJ1287 standard used by MIC, AMA and your local ranger rick is actually quite precise about all those things you mentioned. If you feel hard done by, grab an MIC booklet (see YZ250 forum: how to sound test) and "educate" the sound tester who's doing it wrong. You'll be doing everyone a favour.

If an FMF Q is 101 Db the stock can is 105.

And a White Brothers is 110.


I don't need a decibel meter to tell you that something is wrong with this picture...


Sorry, Techman,

Not that it's your fault, but I can't agree. There may be a spec, but it isn't fairly enforced. In this forum alone, I have heard this same complaint that whoever is doing the testing had the meter at the wrong angle, or too close, or one used a RPM meter and another did not. Depending upon where the testing is done (ie: in the open desert with no vegetation vs in the woods with large trees nearby vs right next to a pickup truck or motorhome), there can be a significant difference in reflected sound. Since the experts talk of reflective sound being "additive" to the total dB, and not just lesser fill noise, it is reasonable that the dB rating will be higher in a more reflective environment than an absorptive one. That is unfair application of the law because some users will have to go to greater lengths to comply than others, just because they have a different tester or are in a different part of the country. I believe judges call this concept "arbitrary and capricious".

Additionally, how can we fairly enforce a law when sometimes the final arbiter (the tester or ranger) has to be told by the user how to do his job properly? I get a ticket or have to sit out an event because the ranger is poorly trained or is located in the forest, but my buddy in the desert with the identical exhaust system and a ranger that knows what he is doing can go ahead unmolested?

Here's the frustration:

We in So California must comply with these sound laws regardless of whether anyone is within 40 miles to hear it. Trust me, no one hikes or backpacks where we typically ride. We must also comply with the requirements for spark arresters. There is nothing, I repeat, nothing remotely flammable in the postage stamp sized areas that comprise our existing open desert riding areas.

So, there must be a reason for our having to comply with very stringent regulations. The reason is that at some point, there are so many tight regulations that some of us just decide it's not worth the fight any more and quit riding and quit fighting those who want us out. We give up and our opponents win. The more regulation they can force upon us, the closer they come to winning the war. It's just that simple. They have won the noise battle. I, for one, don't want them to win any more battles. Hope this helps you understand why some of us have a somewhat surly attitude toward more restrictions.

Cheers, and ride on!


PS: I understand the issues of public opinion. As a result, and for my own comfort, I will eventually be switching to a Q series. I just truly hate being forced to do it for some loser enviro geek who has never been closer to the desert than his own television set.


Sound testing is not as inexact as you make it seem. I have done sound testing for gas turbine installations and it is repeatable if you use common sense. You are correct that the surrounding environment plays a significant role. Unfortunately, the surrounding environment is constanty changing when riding your bike. The real problem associated with sound testing/compliance is the lack of training for those people that are responsible for enforcing the rules.

Regarding this "I just truly hate being forced to do it for some loser enviro geek who has never been closer to the desert than his own television set. "

I don't really consider myself some loser enviro geek AND I have been a lot closer to the desert than my television set. I don't want to hear a 105dB bike when I'm out there on my bike. Yes, I can hear it over my 95dB bike while riding.



I'm not a sound engineer, nor do I claim to be. I just know an arbitrarily enforced law when I see one. Which, I believe is one of your points also when you reference lack of training for enforcement people as the main problem. So, on that we seem to agree somewhat.

I don't know the actual correct reading of a WR400/Powercore IV at max loud, but I seem to recall that 101 is the most cited figure. Based upon the discussions here on TT, it seems that multiple guys with identical setups are getting dramatically different readings from different testers and equipment. 101, 105, whose figures are right? How can we even know how to comply when we can't expect reliable results from different equipment/testers/localities?

There are plenty of annoying things about our sport to others. Someone may not like ANY sound, including your 95dB pipe. Your riding style may be annoying or dangerous to others in the group, but it's not my place to assist others in forcing you to change it.

I just choose whether or not I want to ride in your group, and ask you to make the same choice.

Having said that, as I mentioned elsewhere, I will be switching to a Q series for trail riding. But it's my choice. My issue is that after switching to the quietest performance silencer on the market, I still stand a good chance of receiving a citation, because of aforementioned discrepant results in testing, and because the limits are arbitrarily set somewhat below what the average performance pipes are capable of. I am sure the limits are a result of some negotiation, but it only highlights the fact that it is just another tool that is being used to tighten the noose a little bit. If you don't believe me, wait until they introduce legislation to drop the limits further.


PS: there was a time when 101 dB was all they swore they wanted. Now they want 96, I think. Hell, how about 86? 84? 78? Can you live with that?

Lets set up some general facts about sound tests.

I have made my living doing sound measurements for the past 8 1/2 years at Lexus and Toyota until they closed the Torrance Tech Center in July.

Rule #1

Do not test you machine while it's in the back of your truck. The truck bed is a semi reverberant chamber and reflections will increase the dB level.

Rule #2

The current rule says measurements in the dB-A scale which represents the human ear response to sound levels. It's very east to switch to dB-C scale on most sound meters where nothing will pass. The C scale is a extremely sensitve in the low frequency range where the human ear is not.

Rule #3

Ask to see the sound level with the calibrator installed on the microphone. This will quickly identify if the operator has a clue what he is doing. Most sound level meters made for envorimental testing ship with a 94 dB 1000 Hz calibrator to confirm correct levels prior to testing.

Important fact about dB scale. It's a log scale just like the Richter scale used for earthquake measuremnts. 3 dB drop is a 50% reduction in noise level. So going from 101 dB to 98 dB is a 50% drop in sound pressure level.

Now you know how badly we have been screwed by this new standard.

Impressive, Zaknavage! Looks like you know your acoustics quite well. Actually, a 6db drop in sound pressure will effectivly yield 1/2 the audibe volumne to the human ear. It's all a mute point, however, when it comes to accuracy of testing.

Problem with repeatability of sound level test is that no two bikes project emitted sound exaclty alike. So if you place a db level meter at the same proximity to two different bikes, you will have mixed results. Secondly, if the sound test requires that the db meter be placed 1 meter from the sound source, then it needs to be 1 meter, not .99 meters. An additional .01 meter could add several db's to the test result, again depending on the proximity to the bike.

It is an exact science only in laboratory controlled anachoic environments. If you have the same guy test the same bike at the same location at 10 minute intervals (assuming that he removed and then re-setup the test device each time) the same result will not be achieved twice. Just some of the regulatory bull$hit we have to put up with.

Dan from HB,

You have a valid point of view, but I think you're directing your frustration energy at the wrong people. If you were to have your booklet in your fanny pack so you could raise the calibration and testing environment issues with Ranger Rick as he's wrongly giving you your ticket, odds are that when you show he's doing it incorrectly you won't get the ticket (that goes for anyone, not just Dan).

My response to enduring your slightly heated posts is to ask you to read SAEJ1287 and spread that knowledge to riders and rangers alike. Just trying to make a positive contribution. :-)

x2smoker, your sensitivity of dB's to distance may be a bit exaggerated. Try a few measurements and convince yourself. Additionally, read the sections in SAEJ1287 about repeatability and tolerances for dealing with issues of repeatability. The gist of the test method is field testing vs lab testing. Yes, the idea is also to measure different bikes with different db levels ie two YZ426's, same year, even one with worn out packing and one without as the only difference, so the too-loud bike can be fixed!!! Nobody expects that different bikes will all have exactly the same sound output, instead they just want that sound output to be below a certain threshold. For further self-convincing about repeatability, go test your bike several times in a row at the same spot. If you do the test precisely, you will get the same results within the allowed tolerances (it's not expected to be exactly the same dB value each time!!!!). I'm assuming here you will execute the tests precisely as per spec, not haphazardly. If you get crap results from crap testing methodology, please start over again, studying SAEJ1287 and re-do. Kind of like re-submitting a failing-grade lab-writeup at school. Another point: do you figure there would be a sound regulation if bikes didn't make loud noises? So blame the loud bikes for the existence of the noise regulation! Regulations are reactionary measures to problems!! Seatbelts and helmets got regulated because of a dead-people problem - they never used to be regulated at all. Similar idea with hazardous waste - there never used to be any regulations at all for it!!!

Sorry, I get a bit frustrated with some things some times and mix in some venting with the info.

Dan Yuknavage obviously knows what he is talking about, even if I am full of it. Is there anything you don't know all about, LOL? WE ARE NOT WORTHY......

I have personally witnessed exactly what x2smoker mentioned above. We do sound tests for our D-37 event every year now. We intentionally ran the same bike through the same test repeatedly and saw different results. We experimented a little with "aiming" the meter. It can change the results dramatically. If you alter the 45 degree angle a little, it can further alter the outcome. All these things to me add up to a very unreliable method of determining who deserves a $150 citation and who does not, all due to the human factor.

And that's all I have to say about least until I go to see the judge when I get my first ticket.


How's about you post how many degrees off 45 degrees you went, what your meter was, how precisely you held 20" each time, who stood where during the test, how accurately and how long you held the rpm, etc, and how many dB's difference resulted each time? You can add the other parameters to this list to show you really knew what you were doing during the testing. Maybe you personally witnessed iffy testing, and the deviations were within spec anyway vs you witnessed a real problem. Just saying "I saw it" isn't the same as knowing precisely what you saw by having a trained eye.

The detailed information will help you and others diagnose what's going on. If you don't have or can't recall observing these types of details, maybe that's a clue to why you got varied results, or that the results may have been perfectly ok because they're allowed to vary a certain amount.

Man you guys are really into this. I just wish the testing people could read this! I agree mostly with Dan but excellent points from both sides kept me reading every post.

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