quieting down a YZ400

1 reply to this topic
  • MIyzrider

Posted July 12, 2009 - 05:28 AM


Had this bike for 2 seasons, and last year at the dunes I jacked up my muffler which was alway's a little too loud for my liking. So I contacted "Bill's pipes" (the bike has his complete exhaust) to see if they had a replacement. They sent me back what looks like the old one but it say's "Big Gun" on it. It doesn't matter much to me what it is , it worked and is new again except it seems even louder now, even with the new packing in it. In our riding areas we are now allowed to ride into the local towns , so I really don't want anything obnoxiously loud. I've seen some inserts that are supposed to quiet it down but am wondering if anyone has any experience with them. I found one that I can just unscrew the rear cap and it replaces my arrestor screen but it's a reverse shaped cone and the diameter at the tip so small I can barely stick my thumb thru.. I can't see how the bike would run with one of those, then there's the Big Gun quiet core insert for $50. I think that would work the best but I'd hate to spend $50 and find it doesn't. Are there any recommendations other than a completely new exhaust ?

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  • Chief

Posted July 12, 2009 - 10:43 AM


I have a FMF Q2 with stock header pipe on my YZ400F and it works well to bring the noise level down. I'm waiting for a FMF PowerBomb S/X header that is on backorder. (I'm thinking they don't make it in stainless steel anymore, but it was listed in the ThumperTalk Parts store and I'm hoping to still get one. It is still made in a Titanium but costs more than I want to spend on this bike).
The S/X header is said to bring out more low to mid range where the M/X is said to bring out more mid to top end. The M/X is definitely still available in stainless steel.

Before that I tried a White Bros, E series that I got for free and it was terribly loud so I got rid of it.

FMF now has the Q4 available for it and should work even better than the Q2.
Add a Power Bomb header and it'll quiet the bike a little more, plus it makes oil filter changes much easier because the header pipe won't be in the way.

I know you weren't looking for a full system, but for what's still available for the YZ400F, noise concerns and quality, FMF fits the bill.
Plus the Q2 and Q4 are spark arrestors as well.

I looked at a lot of end caps and plugs, silencers with quiet cores that could be added and finally just bought a FMF silencer that solved the problem.

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