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Quiet Exhaust

By randall996,
in WR400F/426F/450F

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Grand Master

Fryboy

Posted
Posted

The best way to quiet down your WR?????

Turn it off ? I couldn't resist.

I am sure in the next month or two we will see many posts regarding quieting our bikes down. Not sure what my solution will be but for right now if I need to be quiet I insert the baffle. I am waiting for the pipe manufacturers to get on the ball with new designs. Also want to make sure what will pass and what won't with the lame inconsisten test they will be performing. I don't think the testing will be scientific.

Good luck and keep us posted if you find something that works without sucking up all the power.

Fryboy

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Proficient

trailriderjoe

Posted
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I have a WR exhaust on my YZ. To make it well within the Michigan specs (94 Db) I put my own version of the Vortip baffle in.

98YZ400F stock no mods (yet)

tested with calibrated B&K analyzer per SAE J1287 at 4500RPM

Factory WR uncorcked @ 103.1 (no impact to power)

Factory WR with factory insert @ 89.0 (total waste of power)

Factory WR with Vortip insert @ 90.8 (marginal impact to power)

Factory WR with perforated Vortip tubes @ 92.0 (marginal impact but hisses like stock insert)

My advice would be to put a Vortip in and forget about it.

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SFO

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Just a FYI,

I was tested by the Stoneyford USFS this weekend with the CRD quiet exhaust and it did not pass the 96db check.

They also said that it is not uncommon for the Q pipe to fail as well.

Hope some quieter pipes are coming...

Jan 1st is almost here...

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Experienced

neWRiver

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I've tried a Vortip and a BG Quiet core system and both compromised power too much in my opinion and the BG Quiet was not not quiet at all. The Vortip was fairly quiet, but I had a hard time jetting it and never felt good about the power it produced. I've not tried either the FMF Q or CRD yet.

I ultimately just ran my BG in race configuration (loud) and got very good power and gave up on trying to quiet it down. But, I wrapped the header to keep from burning my leg and the excess heat warped and flattened the head pipe to the point that I need to replace it now. Just recently, while running my unplugged stock exhaust I tried a simple turn down tip made by a local guy here in AZ. Basically, it is a variation of home made tips that have been described on TT a few times. It reduces the exhaust outlet diameter slightly, but otherwise is unrestricted.

I've been running this exhaust tip a few weeks and it has been the best compromise of noise and power I have tried. I know it would not pass a 96dB test, but here in AZ we don't seem to have quite as strict sound rules yet. The last local enduro tested at 101db I believe. The primary reason I have been trying to quiet down my bike has been out of respect for public land issues and because I personally don't like really loud bikes.

This simple turn down tip does accomplish a surprising sound damping effect and does not seem to effect power very much. I wouldn't call it "quiet" but it has quite noticeably less "bark" than without. It's about as quiet as the Vortip at lower rpms and only a little louder at mid and high rpms.

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cnacc

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SFO, which CRD pipe do you have? I just got the power II, and it seems louder than it is supposed to. What did your bike test at? I haven't had mine tested yet, I can run at 99 or lower for the local track, and I am curious as to the DB level. ?

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Dan_from_HB

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One of the most overlooked issues is fresh packing. One reason two bikes with identical setups can have different readings is the freshness of the packing. We will likely have to re-pack very often to pass sound levels for '03, even with quiet silencers like CRD and FMF Q.

Another reason, in my opinion, is human error in testing. I realize it is supposed to be to a specification, but it still leaves room for too many variables that affect the outcome. If you can, have them test away from trees or vehicles where echo can play a role.

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StuZ

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cnacc,

I'm running the CRD Absolute Power on my '99 WR400 and it tested at 97.5 - 98 dB at the 49er Enduro in CA 3 weeks ago. They made it a point to tell me that as of 1/1/03, I would not be able to race at that sound level. I have a message to Ligne Racing to see if they have any idea how to gain 2 more dB on that system. It's not the Power II, as you have.

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SFO

Posted
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I am running the absolute power as well.

It has about 5~6 hours on it so I wouldn't think it needs to be repacked quite yet.

I was tested at Stoneyford by Ranger Matt, probably one of the most experienced sound checkers our USFS employs.

I was testing 96~97, BTW.

The Ligne advertisement says 91db.

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SPUTTER

Posted
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I think the vortip compromises the WR250 but not the big bore 400-426. The big bikes don't seem to have have the rejetting problems either (mine works perfectly without rejetting). I've read a lot of posts from people who like the vortip - I'm one of 'em - more power off-bottom with a very slight loss on top - if you ride mostly tight stuff it is mucho good - inexpensive and quiet too.

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