FMF Q4 Muffler (slip on) vs the stock Arrow muffler on a TE250

I decided to try a FMF Q3 Muffler (#045338) on my 2010 Husqvarna TE250. The FMF Q4 is an aluminum muffler for which they claim a maximum of 96 dB. This information probably applies to the other 4 stroke Huskys with an Arrow exhaust for 2011 and 2012 too, like the TE310.

From the dealer, my Husky was pretty quiet, but it had the catalytic converter and the throttle stop then. If you follow the power up directions your remove both of those. And then the bike is really loud, with just the stock spark arrestor. But the power up directions also tell you to take the spark arrestor out and to put the baffle that comes in the kit in the pipe. This does make the bike a bit quieter.

So then you have a problem, if you like a quiet bike. First, with the stock kit baffle the bike still is pretty loud. Second, if you use the baffle, you don't have a spark arrestor.

“danbartol” on cafehusky did a bunch of research and testing on this. His comments are here:
http://www.cafehusky.com/threads/exhaust-db-comparison.8623/

Here are the stock Husky baffle options:

On the far right is the spark arrestor that comes with the bike. The middle baffle comes in the power up kit, and does quiet the bike down, but has no spark arrestor. (The baffle on the far left is a part you can buy from husky. It does quiet the bike down very nicely, but is very restrictive and still has no spark arrestor.)

I ended up welding a mesh screen on the end of the middle baffle (like Dan did), the one that came in the power up kit, and I've been running that. Here is a shot with the screen:

But lately I've been going to some forests and have been concerned that that mesh wouldn't pass muster. And I was hopeful that a Q4 from FMF might be quieter. And I also really like reducing my bikes weight, and the Q4 was likely lighter than the stock muffler.

The Q4 looks nicely blocked up inside, it's not a straight thru pipe:

Additionally, it comes with a spark arrestor that bolts in the end:

Weight comparison:
Stock Husqvarna with baffle: 113 oz (3204g) (baffle with tacked on screen weighs 5.2 oz or 156g)
FMF Q4: 91 oz (2576g) (Note FMF claims 6.1 pounds or 97.6 oz, maybe they count the hardware or something)
So the FMF is about 1.38 pounds lighter! That's cool.

Sound test:
Here was my setup. I roughly followed the AMA standard, by attempting to put the meter 20 inches at a 45 degree angle from the pipe. But my meter is a cheapo and this is not the right environment to test. All I was hoping to do was compare the two pipes. Note these tests are very rough, with me just trying to get the rpm right and then taking a quick look at the dB meter.

Stock pipe:

Q4:

Results:
Stock with baffle and custom on spark arrestor. Cat converter removed.
RPM A weight C weight
2000 88 dB 95 dB
6000 98 dB 103 dB
8000 104 dB no test

FMF Q4 with spark arrestor
RPM A weight C weight
2000 92 dB 98 dB
6000 101 dB 105 dB
8000 106 dB no test

By ear, the FMF Q4 sounded deeper, with the volume approximately the same as the stock exhaust.

So essentially, my results were very similar to danbartol's. The benefit of the FMF Q4 is lighter weight and a certified spark arrestor. The Q4 is no quieter and maybe louder than the stock exhaust with the kit baffle. (Although by Dan's testing it's quieter than the stock exhaust fully uncorked with no spark arrestor or baffle. That makes sense to me.)

Final shot of the installed FMF Q4 on my TE250. The Pirie CF Pipe guard took some modification to get to fit. I also removed the FMF stickers as they don't pay me to run their pipe ;-)

I wonder if you would get lower levels if you were off the cement and on a dirt area.

Also someplace I didn't quite understand your "a wieght" and "c wieght",.

Thanks

A weight and C weight are different ways of measuring the sound. The SAE AMA standard uses the A weighting. I probably shouldn't have bothered with the C.

I'm sure levels would have been lower in a grassy field!

Here is a post I did on my FMF power core, I ended up getting the quiet insert.

I tested the FMF Powercore and was a little surprised. I did not have a tach and I do not know the RPM requirement for a Husky (KTM 450 EXC is 4300RPM). 1/3 throttle I was in the 90's, 1/2 was about 96 or 97 and the max was around 112 db using a meter 20" away and at a 45 degree angle. I will now attempt a link to utube or the actual video.
http://www.cafehusky.com/threads/slip-on-silencer-suggestions-for-te511.27285/page-5


View: http://www.youtube.com/watch?v=-GLFOK4kKKk



View: http://youtu.be/-GLFOK4kKKk

much quieter and sounds better (a little deeper) with the quiet insert.


View: http://www.youtube.com/watch?v=0TywCFydVk8

Q4 Mod tested!
Somewhere on the web I bumped into a great idea to modify the Q4 spark arrestor to reduce the sound.
So I bought an extra spark arrestor for $35 and tried it out.
The idea is that you cut some slots in the end of the arrestor and bend the tabs over the block the pipe a bit. I used duct tape to mark where I was going to cut:

Here are a few shots of the modified spark arrestor next to an unmodified one:

Results:
FMF Q4 with Spark Arrestor
RPM Original Modified
2000 87 dB 87 dB
6000 102 dB 102 dB (whistle sound noticed on modified)
8000 106 dB 106 dB

No improvement! Wow, I really expected this to work. I guess I could bend the tabs down some more, but I don't want to crudely block the exhaust too much. I guess the lesson is that you need actual baffling, not just some blockage.

Another note is that these measurements with the original spark arrestor are a bit different from the ones in my last post a couple days back. Just shows the possible error in these measurements.

This won't work on the Q4. There is an internal baffle, see pic earlier, that prevents a longer Spark Arrestor tube from being used. The Q4 is NOT a straight through muffler.