YZ400/426/450 exhaust interchangeability??

6 replies to this topic
  • Big_B

Posted December 17, 2008 - 08:33 AM


Just bought a '99 400 to play around on. It has a White Bros system on it that is just too loud. So I'm looking for a stock system.

By chance does the exhaust from the 426/450 fit??


  • grayracer513

Posted December 17, 2008 - 09:16 AM


The 426 exhaust bolts directly on. Some exhausts for the '03 -'05 YZ450 can be made to fit with reasonably little work, but don't count on the stock one fitting an earlier bike very well. The snag is that the muffler is welded to the midpipe.

Also, unless your WB is the round R4 with the big ol' hole in the back (which is barely quieter than no muffler at all), the stock 426 exhaust may still not be as quiet as you'd like. They were in the neighborhood of 99-101 db as I recall. If you really want quiet with reasonably good performance, look at an FMF Q4, or a used Q2.

  • jayh300

Posted December 17, 2008 - 09:24 AM


correct.... as usual gray.
my 99 400 with the wb E and 4 discs would hit 100db with any throttle at all.
I bought a used 426 stocker and it bolted right on, but was still 92-93 db at idle. My ears would not ring for days after riding it, but it was still pretty loud.
I have a db meter, sound guy, and that is with it sitting on the seat of the bike. And remember, as far as a db scale goes, every 10 db increase is twice as loud. so 100db is rated twice as loud as 90db in "spl" sound pressure level.

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  • frankllynn

Posted December 17, 2008 - 09:01 PM


My stock 98 400 exhaust is louder than my Pro Circuit exhaust.

  • MuDPoUNdeR

Posted December 18, 2008 - 04:29 PM


You know I just recently got a Stainless T-4 for my 426 and it came with a silencer in it and makes the bike pretty quiete. When you take the silencer out of the pipe its just as loud as the FMF Q pipe but much better performance.:thumbsup:

  • divebobber

Posted December 19, 2008 - 10:18 PM


This discussion seems like a good place to ask this question. I have a 2000 426 with a White Bros pipe on it. I took as many plates as was recommended (down to 4) and it was still too loud. I was going to go to Carnegie for the first time a few weeks back and was worried it might be over the db limit. It has a solid plate spark arrestor over the end so I tried something that's kind of Joe McGee. I took about a half of one of those stainless steel pot scrubbers and stuffed it into the end of the pipe. It couldn't come out because it would get blown out and compressed against the inside of the spark arrestor. Depending on how much of the stainless steel wool I put in I could quiet it down to a very mellow four stroke sound. It reminded me of how my old Honda XL 250 stock muffler used to sound. It definitely softened the power but not terribly. I'm starting to think about going back to that, both for the decrease in noise and the fact that the mellower power might keep me healthy longer (4 rides...two injuries). The question I have is, do any of you more experienced folks see anything this could do to hurt anything?

  • MuDPoUNdeR

Posted December 20, 2008 - 12:51 AM


Heat and power. By choking it you will build up heat! There is heat tape on the back side of my number plate on my 426 to help from the plastic melting. I couldn't tell you how hot it may get though ... Of corse since you are choking down the bike you will loose some power, but I'm sure not enough that you will notice unless you really pack that stuff in.

I personally wouldn't do it. Just my feeling about it. I would look for another technique for dampining the noise. FMF has the super bomb will help a little bit and combine that with a Q pipe I think would make for a decently quite system and some good torque :thumbsup:

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