DRZ-E and WR426 Sound testing completed.

Uechi45

Member
Dec 11, 2000
44
0
I finally did the sound testing on my DRZ-E and my Son's WR426. I tested both bikes 3 ways.

1. Pure stock
2. Custom made exhaust cap
3. Exhaust restrictor (cap) removed.

All testing was done with a Radio Shack analog meter set to "A" weighting, 20" away at a 45 degree angle. The 1/4 trottle setting is just an estimate but all testing was done at the same setting.

Lets talk about the DRZ first. The custom cap consisted of a plate with a piece of 1.5" i.d. thin wall tubing 2" long welded to it. The spark arrestor is stainless steel screen welded to the inside. The air box snorkle was removed and jetting richened up.

Stock at idle = 84 db
Stock at 1/4 throtle = 96db

Custom cap at idle = 85 db
Custom cap at 1/4 throtle = 96db

Stock cap removed at idle = 93db
Stock cap removed at 1/4 = 102db

The WR426 gave very interseting results. The custom cap (actually an insert) is a plug with a 3/4 inch hole drilled thru and retained by the stock restrictor screw. Stock jetting and stock air box.

Stock at idle = 83 db
Stock at 1/4 throtle = 116 db

Custom insert at idle = 85 db
Custom insert at 1/4 throtle = 110 db

Stock restrictor removed = 92 db
Stock restrictor removed at 1/4 throtle = 116

I can't understand why the stock insert and no insert gave the same reading. They have a different sound, but the little stock insert is very loud in a different way. I suspect that the frequencies are different to our ears but the meter can't tell the difference? Tests were run several times to make sure of the results.

Any way, that's what I did. Any suggestions or comments are greatly appreciated. I will post this at Thumpertalk as well.
 
Oct 30, 2000
53
0
wot - no one's replied??

most 426s i've come across have, not only been loud, but (if you stand where the meter would have been) goolie ganglingly loud.!!

prob has someting to do with the massive diff between idle noise & revving noise (83db to 116 db).
 

techman

Member
Feb 18, 2000
95
0
Go to thumpertalk, in the YZ250F forum there's all you need to know to get straightened out about sound testing correctly. Doing it right will probably fix your results vs what you expected.
 
Top Bottom