Loud Snowmobiles

Tech Shorts September 15, 2007 1
One of the false stereotypes our industry continues to fight is that of noise. The occasional piped-sled with open stingers or burnt-out packing in...

One of the false stereotypes our industry continues to fight is that of noise. The occasional piped-sled with open stingers or burnt-out packing in their mufflers makes non-snowmobilers think that all snowmobiles are this loud, but we all know that to not be true.
Nationwide, there is a backlash against loud recreational vehicles. This includes resentment against the sharp increase in loud motorcycles. Riders install loud “pipes” on their street bikes, and produce noise levels that far exceed that of snowmobiles. Law enforcement agencies and legislators are hearing from the populace that “enough is enough”. So why all of the attention with snowmobile noise when motorcycles are so much louder?
Nowhere is this “double-standard” more evident than in Yellowstone National Park. While snowmobiles can not enter the park unless they meet noise regulations that are far more stringent than for the rest of North America, loud motorcycles pull into the park relatively unchecked and unrestricted. So, how is that fair? It isn’t.
All new snowmobiles are manufactured to pass two intense sound test procedures. They are certified by a third-party, internationally-recognized testing agency which administers the two rigid sound tests. First is the SAE J-1161, which is a steady-speed pass-by test, and the second is the SAE J-192, which tests the vehicle in the most extreme operation condition; wide-open throttle acceleration.
When following the SAE J-1161 test procedure, the machine can generate no more than 73 decibels at the steady speed of 15 mph. When following the SAE J-192 test procedure, the machines at full throttle can generate no more than 78 decibels at a distance of fifty feet, with a 2 dB allowance afforded for variances in environmental conditions. So, in effect, 80 dB at fifty feet is as loud as a “certified” stock sled can ever be when measured at fifty feet. Remember, this is at FULL THROTTLE.
Curiously, many road vehicles emit a higher amount of noise than snowmobiles when the J-192 procedure is followed. Some vehicles, like trucks and motorcycles, were measured at levels up to SIX TIMES the legal limit for snowmobiles. Again, a double standard?
The SAE, working with other government agencies, has recently developed a special “in-field” test procedure titled SAE J-2567. This procedure is aimed at allowing enforcement officers to test a machine in a stationary position. The most important thing to remember is that a noise limit should be applied equally and fairly across the board. None of this lifting the hood and declaring a sled in violation simply because a modification has been made. Stock or not, each sled should be subjected to the test without bias, and if it passes, so be it. If it fails, so be it. Because, a good number of sleds that were supposedly “compliant” at the time of their manufacture are no longer in compliance due to deterioration of their mufflers. And, a number of “modified” sleds will prove to be as quiet, and quieter, than some of the stock sleds.
The bottom line here is to eliminate the truly loud snowmobiles from the public trail system, which causes user conflicts and ultimately is used against us in land closures and access issues. Loud sleds have no place on the trails of 2008, and now enforcement agencies have a legal method of keeping the noise to an enforceable limit.
It is only a matter of time before this same principle is applied to the loud motorcycles that are disrupting the highways across North America. An exhaust that rumbles is one thing; outright loud and obnoxious machines are simply rude and demonstrate disrespect for the privilege to ride.

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