轉貼 自
http://www.dirtbikeworld.net/forum/archive/index.php/t-52383.html
Battered Sav
18-12-2008, 10:15 AM
Some more, hopefully helpful, info. :)
EnviroRider (Roger Pitt) and Simon (Simon White) from the DSE Trail Bike Project conducted voluntary noise testing prior to the ride. The noise testing process used a digital tachometer to verify engine rpm and a digital sound level meter to measure noise emission.
The legal maximum is 94dB(A), but it's better to be under, especially in view of the fact that the test rpm is very low, much lower than what you're typically riding at, so noise output is always going to be higher than during the test. Here are the results:
Wombat State Forest Sunday February 3, 2008
KTM 525 87 dB(A)
KTM 125* 84 dB(A) (Official test rpm 3500)
KTM 520 98 dB(A) (Non-standard muffler end-cap, needed repack)
Suzuki RMX 250* 84 dB(A) (Official test rpm 1750 which is unrealistically low)
Gas Gas 300* 89 dB(A) (Official test rpm 4150)
KTM 520 89 dB(A)
KTM 250 90 dB(A) (Akrapovic muffler)
Yamaha TTR 230 95 dB(A) (Standard system, baffle removed)
KTM 450 96 dB(A) (Pro-Circuit muffler)
KTM 400 88 dB(A)
Suzuki DRZ 250 91 dB(A)
Honda CRF 230 82 dB(A)
Yamaha TTR 250 101 dB(A) (Staintune muffler - standard is 79 dB(A))
* 2 stroke
The noise test is conducted with the Sound Level Meter 500 mm (0.5 metre) from the exhaust outlet, at the same height, at an angle of 45 degrees to the side.
The test RPM is set down for each bike and is 50% of the RPM at which that bike develops maximum torque. There are some apparent oddities which I am investigating further, eg. in the 2008 Yamaha 250 range a WR250 F is tested at 3250 rpm, a TTR 250 is tested at 3500 rpm, and a WR250 R is tested at 5000rpm. For comparison, a Honda CRF 250 is tested ar 4690 rpm, and a Kawasaki 450 at 3000 rpm. Note that these figures are all supposed to be 50% of max. torque.
The sticker is affixed to every new bike and is titled Stationary Noise Test Data. It shows the required test rpm and the decibel level with the stock exhaust. On most bikes it is on the frame near the engine or on the headtube. On Hondas it is on the side of the plastic rear guard.
Roger Pitt
Trail Bike Project Manager
DSE
EnviroRider (Roger Pitt) and Simon (Simon White) from the DSE Trail Bike Project conducted voluntary noise testing prior to the ride. The noise testing process used a digital tachometer to verify engine rpm and a digital sound level meter to measure noise emission.
The legal maximum is 94dB(A), but it's better to be under, especially in view of the fact that the test rpm is very low, much lower than what you're typically riding at, so noise output is always going to be higher than during the test. Here are the results:
Wombat State Forest Sunday February 3, 2008
KTM 525 87 dB(A)
KTM 125* 84 dB(A) (Official test rpm 3500)
KTM 520 98 dB(A) (Non-standard muffler end-cap, needed repack)
Suzuki RMX 250* 84 dB(A) (Official test rpm 1750 which is unrealistically low)
Gas Gas 300* 89 dB(A) (Official test rpm 4150)
KTM 520 89 dB(A)
KTM 250 90 dB(A) (Akrapovic muffler)
Yamaha TTR 230 95 dB(A) (Standard system, baffle removed)
KTM 450 96 dB(A) (Pro-Circuit muffler)
KTM 400 88 dB(A)
Suzuki DRZ 250 91 dB(A)
Honda CRF 230 82 dB(A)
Yamaha TTR 250 101 dB(A) (Staintune muffler - standard is 79 dB(A))
* 2 stroke
The noise test is conducted with the Sound Level Meter 500 mm (0.5 metre) from the exhaust outlet, at the same height, at an angle of 45 degrees to the side.
The test RPM is set down for each bike and is 50% of the RPM at which that bike develops maximum torque. There are some apparent oddities which I am investigating further, eg. in the 2008 Yamaha 250 range a WR250 F is tested at 3250 rpm, a TTR 250 is tested at 3500 rpm, and a WR250 R is tested at 5000rpm. For comparison, a Honda CRF 250 is tested ar 4690 rpm, and a Kawasaki 450 at 3000 rpm. Note that these figures are all supposed to be 50% of max. torque.
The sticker is affixed to every new bike and is titled Stationary Noise Test Data. It shows the required test rpm and the decibel level with the stock exhaust. On most bikes it is on the frame near the engine or on the headtube. On Hondas it is on the side of the plastic rear guard.
Roger Pitt
Trail Bike Project Manager
DSE
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