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In 1971 in effort to fight noise problems, MIC adapts slogan; “Less sound = more ground.” Cant find the old Kent Howerton ad for it though.
Well if you can see the need for lower sound levels on the pro and AM side of our sport idk what to tell you. Unless you want to embrace e-bikes which is not something I want to do.
Same picture just bigger - easier to see header. The Vital IG post 2nd picture has a better closeup.
And from Vital's IG
, ithtemporary icreaes someEven Laguna Seca has sound limits in place for races. Sad but true. I like the sound of bikes or cars screaming at high rpm, but I'd rather have a quieter race than no race at all.
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Noise doesn’t add like that. There are marginal increases with multiple sources, but it isn’t simple math of “100db x 22 riders = 2200 dB”
Those resonators are doing more for sound mitigation (especially in regards to what they're designed to do; eliminate/reduce specific frequencies, also note they're different lengths) than the length of the header pipe. The length of the pipe has more to do with moving the power characteristics around.
As a kid I had an 84 KX 80 with a worn out silencer. It must have been at just the right frequency. People miles away could hear me and those were country miles I’m talking about. In hindsight I feel a little bad for the neighbors.
The bikes make plenty of power nowadays. No reason not to quiet the exhausts.
If you do an indoor event, it's not super nice noise levels. So brining it down helps. Experience for casual fans and kids having to sit with ear muffs, not great. Heard this from multiple friends with kids. It's the same for me if arena is with roof and it's covered, need to use NC headphones and you can't speak to the friends without screaming.
I don't think that's the biggest reason, but it is a reason. Of course outdoor MX is the big topic, and why would we have two different rules? Would only benefit factory teams having resources to develop dual setups. I don't think even them wants it, if it was possible.
I get that. I would be curious what the actual difference between 1 monster truck vs 22 bikes inside and outside the stadium.
Anyways I have no idea why pro bikes are being muffled for pro events meanwhile local stuff is wide open. I think it should be backwards. OEMs, FMF, PC, etc. should focus on making better packing and designs for consumers and the professionals should have factory parts.
Difference is notable just between 1 and 22 bikes running. 22 bikes you have constant full gas on a few bikes so noise level builds up quickly since it's also bouncing in the stadium. During a sprint lap with a single rider like in Paris, or WSX, you have no issue talking to people around you. Impossible in an indoor Stadium (also difference between size of stadium of course and what level you are sitting at.)
Even if a monster truck would be peak louder, there isn't a constant high level like for a 15 or 20min SX main.
You want answers?! 🤣
Come on man....the only thing backwards here is you...you've had your questions answered here and in the other thread you ruined...move on FFS...
I think you just might be the most downvoted member of the board...congratulations on that!
Wouldn't one reason for sound be to limit/modify horsepower?
It feels like the twilight zone on this forum sometimes.
Only one person is in a twilight zone and it is you….but of course a narcissist like you would only assume everyone’s opinions are wrong except theirs…
Articulate my perspective back to me.
(Thanks for the psychiatric diagnosis too)
You guys know that sound reduces dramatically over distance right? The average is 6db loss over each 3.3 ft or (1 meter) away from the source. The closest rows available sit at any stadium are row 6. That's 40ft (12 meters) away. Now simple math can show you clowns how large the sound decay is and why sound testing should be eliminated for Professional Events. AMA's sound test db limit is 112db pre-race, 113db post-race. So lets say 112db - 6db every 3.3 ft = 39.28db you actually hear at 40ft (12 meters) away....That's a 72.72db reduction. Sound is a non issue and infants still wear earmuffs just in case. AMA needs to cut the bullshit with the ridiculous sound violations they've been giving out as well.
Pit Row
Downvotes dude downvotes….if that doesn’t clue you in I can’t help you….
It’s obvious Owen here is your local Unlimited C/D hero, rev bombing his YZ250F with blown out muffler packing all by himself on the starting gate while everyone shakes their heads.
I’m just ready for this whole ICE thing to be over with. Can we just go electric already?
Funner. Quieter. Less drama. Less maintenance.
When we are all on electric bikes the sport will grow more. Less tracks getting shut down. More tracks opening up. Everyone will be happy. 😃
Airbox intake, engine mechanical noise also contribute to overall db. When I worked at supertrapp/kerker we needed to be at 72db on one project. We could make the exhaust output quiet and flow well but the airbox and engine noise was something we couldnt address. Perf tube hole %, length, volume of the can and the type of packing are the only thing that will dampen the exhaust pulse wave.
Actually, it is the manufactures that are pushing for reduced sounds (executive level staff), not the AMA as most people would assume. That said, it has turned out to be more challenging than originally anticipated and those the subsequent need to push the new sound requirements from the original 2026 implementation to 2027. From a bottom-line standpoint one might surmise that lower sound translates into better PR and ultimately increased bike sales. So... unless there happens to be executive level staff on this forum you probably will not obtain a formal vetted answer to your question.
Ok you've had experience building pipes and I'm interested in what they are doing here. Besides the resonance chambers, they have obviously added a lot of length. So much that if it were a front center port like a Honda, that can would be at least two feet past the fender. So, let's assume they are trying to break up the pulse wave, wouldn't that also cancel scavenging or using pulse wave for tuning? They went through a lot of trouble to NOT make a better muffler.
He was told that 10 times in the other thread…this guy is nothing but a useless troll…
I remember the first time I got behind a yz250F after the first turn of a race back in 2001. It was a full gate and I came into the first turn in 3rd behind 2 of those things. I thought my ears were going to explode.
Crazy how 25 years later I can be around 40 of them and it not bother me. Although, I am partially deaf in one ear these days. I wonder how that happened….
Why do you post shit like you know it before googling it?
Using the 113 db sound limit post race and using “your” math you are telling me that inside of a stadium at a supercross race we are only hearing approx 41db? What is an example of 41db? When I search for this information it ranges from light rain-babbling brook-average home noise- computer hum… my experience says that you can only communicate by yelling at the person next to you. That is far from a non issue.
Exactly, guy is delusional thinking people in row 6 are only experiencing 40db.
Direct injected car engines use foam on the engine cover to quiet chattering, im honestly blown away we dont have them on our fourstroke heads. Guaranteed its some decibels. Cheap, easy and light. The mechanical noise is a big factor with valves not just the intake and exhaust. Let alone the benefits for dual sports, it is said the tires they select are specific to noise issues for that certification as the bike actually rides by the tester on pavement. Point being, a sound deadening cover for the head like cars likely would help.....probably help the fuel not boil too lol.
Oh man pro circuit and fmf hurry up and take my money. My model is a 2021 but this will work with all 2014 up models most likely. Also duh duh duh- can tuck the muffler in even more hopefully. Longer headers typically have very little down side beyond weight. And guys need some type of new tech, this is a very smart team. Get the heat away from next to the cylinder/under the throttle body too. Brilliant
Someone download the NIOSH sound level meter on their phone this weekend and let’s see
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