TEN THINGS ABOUT THE AMA'S NEW SOUND TESTS

Yesterday at 12:30 PM

(1) AMA rule. The sound requirements for pre-race inspection are set at a max of 112 dB/A and for post-race inspection the max is 113 dB/A. However, the AMA deducts 2 dB/A on each test for “corrections” in their sound meter, which really means the rule is 114 dB before and 115 dB after racing. They also allow the bikes to be an additional dB louder when ambient temperature is below 50 degrees.

(2) Round down. The AMA has tightened things up for 2025, taking away the “round down.” Previously, a 114.9 dB/A reading was counted as a 114.0 dB/A, which was then counted as a 112.0 dB/A with the deduction, but now, they’re holding the line at 114.0 and more riders are failing to pass sound testing than ever.

(3) Future rule. The 2025 AMA rulebook warns that the sound restrictions for 2026 and beyond will go down to 109 dB/A for pre-race and 110 dB/A for post-race inspection. This is a massive reduction in sound from the current 112 dB/A; however, it’s unlikely this rule will go into effect next year. The MXGP series dropped from 114 dB/A to 111 dB/A in 2025, and they plan to go to 109 dB/A in the future.

(4) Purpose. You might be surprised to know that it’s not the stadiums, cities, tracks or even the AMA that is asking for this rule change; it’s the OEMs. After all, Feld hosts Monster Jam in the same stadiums as Supercross, and monster trucks are much louder than dirt bikes. The manufacturers know that tracks are closing at a rapid pace around the world, and in Europe, noise is one of the driving factors for track shutdowns. In the U.S., insurance lawsuits are the primary cause of closing tracks, but the OEMs think that quieter bikes will help tracks stay open worldwide. When you add in the fact that the OEMs currently have to make exhaust systems that are quieter for the European market, they want one universal sound regulation to lower costs. 

(5) Privateers. Thankfully, the AMA doesn’t plan to lower the sound requirements below what the stock OEM bikes produce. They don’t think it’s fair for a privateer to buy a brand-new 2025 Yamaha YZ250F and take it to Supercross only to fail sound testing on the first try. 

(6) Power. Making a bike quieter can sometimes rob some horsepower, but it almost always hinders throttle response. Kawasaki was the first manufacturer that intentionally sabotaged its new four-stroke engines to make them quieter. The 2024 KX450s and 2025 KX250s are quieter, thanks to their choked-up airboxes. Peak horsepower on the dyno didn’t suffer as much, but throttle response and engine excitement did. The other OEMs are currently developing bikes to meet the 109 dB/A standard, but they don’t want to release them to the public until all of the major OEMs agree to stick to the new sound rule. Aftermarket turners and exhaust companies will benefit from the new sound rules, because the OEMs will have to “choke up” their stock exhausts and ECUs, leaving more power to be made in the aftermarket. 

(7) Testing procedure. The 2-meter-max test measures the sound levels of the bike with the engine going quickly from idle to wide open. The sound meter is set on a tripod on the right side in a 45-degree position from the centerline, 79 inches behind the motorcycle and 53 inches above the ground. The AMA conducts these tests for every rider on Friday before a Supercross, and they randomly select riders to test on Friday before the races at the Nationals. 

(8) Tricks. You might be surprised to learn that reverberating noise from the airbox is sometimes louder than noise from the muffler. On many bikes, including Ken Roczen’s RM-Z450, mechanics have to close off the vent to the airbox on the right side of the bike to keep sound away from the meter. 

(9) Cheating. Putting a rag in the airbox or creating special maps are two common cheats. New for 2025: The minimum rpm for the 250 class went from 12,500 to 13,500 rpm, and for the 450 class, it went up from 10,000 rpm to 10,800 rpm. It’s easy for tuners to make specific maps that retard the ignition to make the bike run quieter while in neutral; however, rules have evolved to ensure the mechanic puts the bike in gear and pulls in the clutch during the test. 

(10) Penalties. The AMA allows an extra 1 dB/A in a post-race test. Penalties include your fastest lap time being taken away after qualifying, or subtracting three points from your score after a race. Jordon Smith failed the sound test in both qualifying and after Moto 2 at the 2024 Southwick National. His fifth overall remained, but he lost three points.