96db question

[MN_Paul]

I have an 05 WR450 and I will be riding it in some events that do a sound test (96db) before you can ride. What options are available to achieve this with the stock exhaust?

Thanks

[Ramcc4x4]

I just had my 2006 WR450 tested this weekend at Hollister Hills. I had a total of 27 miles on the bike so the packing was basically brand new and with the Pro Moto Billet insert in the stock pipe and Utah skidplate I tested at 94.5 db. I mentioned the skidplate because some people feel the skidplate can cause a higher db reading depending on the conditions.

[JRAMBO]

I would just pull the little insert out and run it like that it will be under 96dbs I have an after market White Bros.E-2 and with new packing it comes a little too close to 96 for me.Which is supposed to be a 96 dbs pipe.

[1BLUEsky]

I did a hare scramble on my 03' using the stock pipe with the GYTR insert from Yamaha and If I remember right I was around 95 db. The muffler had about 700 miles on it.

[JSanfilippo]

I just had my 2006 WR450 tested this weekend at Hollister Hills. I had a total of 27 miles on the bike so the packing was basically brand new and with the Pro Moto Billet insert in the stock pipe and Utah skidplate I tested at 94.5 db. I mentioned the skidplate because some people feel the skidplate can cause a higher db reading depending on the conditions.

I don't think the stock WR pipe has packing. Just 3 evenly spaced baffles, the spark arrestor, and the end cap insert. Someone correct me if I'm wrong

[Just_a_trail_rider]

I just had my 2006 WR450 tested this weekend at Hollister Hills. I had a total of 27 miles on the bike so the packing was basically brand new and with the Pro Moto Billet insert in the stock pipe and Utah skidplate I tested at 94.5 db. I mentioned the skidplate because some people feel the skidplate can cause a higher db reading depending on the conditions.

How does the skidplate make your bike louder?

[JSanfilippo]

How does the skidplate make your bike louder?

Instead of the sound waves caused by the engine noise going down to the ground it bounces off the skid plate and is redirected up towards the rider.

[pkcof]

yes, i would call it a mechanical baffle (similar in theory to the staintune - but obviously not up to scratch) although it does have a thin packing 'skin' as an inside layer to help dampen the vibration/resonating effect.

Considering the demands put upon Yamaha (and others) to comply with varying levels of noise acceptance from around the world (and the lowest common denominator usually wins) it is a reasonable compromise - luckily it is not overly difficult to 'modify' within reason !