Rocky Mountain Dirt Riders

The technique for sound testing is listed on our race page.

All bikes were tested for sound at the Porky's XC race. I thought we could share our sound level results here.

Please reply by posting your bike description and muffler type as well as the sound level (pass or fail) so that we can all learn what works and what doesn't.

2006 KTM 250XCW with FMF Gnarly pipe and stock silencer.

89db

What did your bike test at?

06 300 XC-W, stock pipe, 88db

'06 Gas Gas EC300 Modified stock silencer with S/A installed. 91db. Stock pipe.

'03 250SX with an FMF Gnarly pipe and a silencer off an '05EXC. I tested at 90db

Almost all the 2 strokes pass the sound test-what about all the 4 stroke guys we tested-some of you did not pass- most off-road ready 4 strokes passed anmd not 1 mx 4 stroke passed without exhaust being changed

06 450EXC stock exhaust with spark arrestor

94.5 db

06 yz 450 stock 102.5 db
with Q2 silencer 98.5 db
these yami's are loud
My FMF Q2 is for sale $350, only used for 2 months. I am going a different route.

Is there any experience with how loud a Suzuki DRZ400E is? I have a 400S (dual-sport) that I am vamping up a bit and I have purchased a stock "E" tailpipe and S/A for it. The purely off-road "E" pipe is a bit bigger and should flow better than the really chocked up "S" pipe.

I have also picked up a fatter FMF header pipe to feed the "E" tailpipe, but I don't imagine the header will affect the noise output much.

Alternatively, is there a way I can get this setup noise tested after I mount it all up, so I'll know, before I head out to any events, whether it's going to be OK regarding volume?

A stock DRZ 400E muffler is very quiet ( in the mid 80 db) It is also fairly choked up as well. It may flow slightly better than the "S" version though. You will be able to tell when you get it on there, how much difference it makes. I do know from working on a friends 2001 DRZ 400E that the stock jetting is very lean and the bike really woke up with the jetting being updated to flow a little more fuel. Good Luck--- WR Dave.

Thanks WR, good to know I'll have no decibel worries with the stock "E" system swapped onto this bike.

This model also needs the same jetting attention. I started with a Dynojet kit that included a skinnier needle. Much better. Will finish the rest of the drill once I have the new exhaust in place. Pilot end is OK presently, but the main is already undersized. With the pipe added, it'll need further attention across the range.

Wheelies to follow!

FYI

A ton of Euro factory teams use Akropovic systems, whether the full system or the slip on. THey all pass a very stringent 94 dba FIM sound test. The Akro systems are top quality, durable, make good power, and most of all are reliably quiet.

Leo Vince makes an excellent slip on as well. makes power and passes sound. friggin ugly though, looks like a monster torpedo off the back end. even though it is huge it is lighter than stock.

Big Dog wrote:06 yz 450 stock 102.5 db
with Q2 silencer 98.5 db
these yami's are loud
My FMF Q2 is for sale $350, only used for 2 months. I am going a different route.

My old 03 wr450 was the coolest sounding bike ever! Full custom titanium pipe to a titanium slilencer. It was like some evil helicopter! I miss the sound.

'08 YZ450F Stock setup, tested three times: 116db, 108db,109db. I don't know why the first one was so loud, maybe a fluke?

Hi,

Just to clarify, the 450 mx bikes with stock exhaust systems failed sound testing?? Also does no spark arrestor mean that you are not able to race?
Thanks