Is there anyway to silence my YZ400 exhaust.

I mean is there an end cap that I can buy/use to make it less noisy.

Its just too loud and i don't like how the WR exhaust looks like.

Any ideas?

Check out, they have a spark arrestor with optional quiet end cap for about $150.00.

I have not heard of anything else. I have been looking for my friend who also has a YZ400. Drilling and riveting required with the pmb system.


I have a funny suspicion that your silencer is in dire need of repacking. When's the last time you drilled out the rivets?



Point taken. I'll repack it and see what happens.

Will new packing really help to soften the sound?

Anywhere near the WR exhaust?

I hope so..

the difference in sound can be quite drastic w/ a fresh re-packing BUT you will NOT achieve the noise output of a "CORKED" WR exhaust.

To lower your noise, prepare to lose some performance.

What about the looks of a newer WR exhaust? I know the older ones are black, but the newer ones are Stainless and look pretty good I think. Not sure how the fit is on a 99 YZ however...

I believe that i WILL have to LOSE POWER to keep the exhaust quiet but can i get more power but with less noise?


Keep in mind that i want to use my YZ exhaust.

Looks much better and does not get too close to my side plastic and burns it up.

I too have a YZ muffler on my WR400 (98). After a 6 month storage, starting it up revealed exhaust coming out of the front of the muffler (toward the motor) around the outer casing between the rivets. Since it was smoking due to the oil in the cylinders, this was easily seen. Any clues on that one? I haven't drilled the rivets out, but wondered often how you would repack it...anybody have experience on that they'd like to share? I'm sure it's simple, but the experience from someone already familiar with it saves lots of time.

Yeah I will take a stab at that one. There is no packing left and the exhaust gasses have a straight exit point at the rivets. Get a repack of silencer packing and drill out the rivets. You'll be surprised at how much packing is missing. The bike will run alot crisper with a new repack.


Just out of curiosity, is it necessary to drill out the forward and rear rivets, or just the rear ones? I assume to reassemble, you simply re-rivet the case back on, right? Sorry for the basic questions....

I bolted my FMF powercore of my 2002 yzf on a yz400 and it fit fine, the powercore comes with an extra quiet end cap, you can switch end caps whenever you need, the quiet cap does rob some power but that cant be helped

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