I have done alittle research on db sound levels, but don't know if I'm heading in the right direction. This is what I've come up with:

104dB with stock pipe
116dB with E-series pipe(12 discs)
And a claimed 5-6dB decrease with quiet core insert placed in pipe.

I love my E-series pipe(great for racing), but would like a way to cut the sound back for trail riding. I don't want to disturb non-atver's.

Would a 5db decrease be noticeable?
Will it hurt the performance of the pipe?

My info: Machine is a 300EX. I trail ride at a meduim pace. The machine is built for racing, so I can sacrafice alittle power for quieter ride.

Thanks in advance.

Chris

 

I bought the quiet core insert for the e-series silencer on my 400EX. It significantly reduced the sound level- it seemed about half as loud with the same number of disks (12). However, I found the new sound very annoying. It was a higher pitched sound and made the silencer buzz and rattle. I took it out immediately without even riding it.

Since then I have talked to the service department a White Bros. and learned that the insert doesn't necessarily have to be installed per the instruction sheet. The instructions sent with the insert said to install it in place of the first disc. The guys at WB said they were experimenting with different locations other than the first disc- with good results. I haven't tried it yet but I can see how that would probably help some, although it would be louder.

In case you were wondering how the insert is constructed: they use a standard disc with a hole cut in the center and a perforated tube is welded to that hole. The perforated tube is slightly smaller in diameter than the perforated tube inside the silencer. The end of the perforated tube that goes in the silencer is flared to fit tight within the silencer's tube. At the other end the disc bolts in place to support the tube. Inside of the insert's tube there are three washers welded in place- one at each end and one in the middle. They look just like 1/2" ID fender washers. Exhaust gases are forced through the small 1/2" diameter holes of these three washers and out through the hole in the disc. Something I've considered doing is enlarging the size of these holes and/or removing one or more of the washers.

 

I had a E-Series Pro Meg and quiet core insert on a 2000 Warrior that I sold to buy my 2000 400EX, and I had the same results with the rattling noise when it was installed in place of the first disc. When I did run the insert I usually installed it in third place with two discs between it and the muffler, with another 8-10 behind it, and it was quieter but not as quiet as a stock system. Any more than two discs though and it just didn't sound right...don't know why but it seemed as if the exhaust was too restrictive. The point I want to make though, is that I was able to get the pipe to an acceptable noise level just by running the minimum amount of discs (four), so I would try that before spending the money for an insert--mine spent a lot of time on a shelf in the garage.

 

Thanks for the advice.
I haven't tried removing discs from the pipe yet. So I guess that's my next step. I've heard that going down too only 4 discs will take away top end, and add too the bottem end of the powerband. I don't want to have to re-jet everytime I play with discs. I have a ton of mods, so I know that the jetting is real fussy. I guess with alittle tinkering I should be able to get the exhaust tone down to a suitable level.
Thanks again for the help.

Chris