kelabar
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Post by kelabar on Aug 4, 2020 23:25:19 GMT 10
Looking to make up a quieter exhaust for a 600cc 4-stroke single. The current exhaust is LOUD. There is only one baffle inside with two holes in it. Anyone made up a bike exhaust? What are the main ways to reduce exhaust noise?
I assuming the exit hole on the muffler needs to be the same size as the current one due to getting rid of 600cc of exhaust for each firing. What about inside? Do multiple baffles reduce noise? As a rule of thumb I guess the size/area of the holes in the baffles need to be roughly the same as the area of the exit hole to allow unrestricted flow of the gases, but can be multiple holes as long as the area is the same. Sound right? Steel construction (current one aluminium). Quietness is more important than weight so is thicker steel quieter? Flyscreen inside reduces noise but isn't durable enough. TIA.
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bug
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Post by bug on Aug 5, 2020 9:24:39 GMT 10
Find whatever the 'bikies' on their fart bikes do, and do the opposite...
I'd be a bit careful playing around with an exhaust like that. Surely there's a commercial exhaust that is quieter?
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kelabar
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Post by kelabar on Aug 5, 2020 10:13:17 GMT 10
Surely there's a commercial exhaust that is quieter? Sure, but I don't learn anything that way. A basic understanding of how to keep engines quiet could be handy ATSHTF. Plus sometimes it would be nice to get off the bike and not have my ears ringing!
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Post by spinifex on Aug 5, 2020 18:35:38 GMT 10
When you want to make a station genset quieter ... or a gun ... you vent the exhaust gas into a larger volume receptacle. Stick a big Milo tin on the end!
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bug
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Post by bug on Aug 5, 2020 20:07:47 GMT 10
There was one of those dickhead loud exhausts on my car when I bought it. Mechanic swapped it for a normal one for free.
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kelabar
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Post by kelabar on Aug 5, 2020 20:32:59 GMT 10
I wouldn't ride a quiet bike on the road. Ever. Car drivers are dangerous enough as it is. I always give it a 'blip' if they don't know I'm there.
Looks like there are a couple of addition options. A baffle that slips into the exhaust outlet reduces noise but probably not enough for what I'm looking for. This is just a short length of pipe with a heap of small holes in it. Can add another muffler after the existing one. Once mounting had been sorted this would be a quick way. Or a 6 ft length of flexible metal conduit in a coil attached to the outlet hole will quiet an existing muffler apparently.
Also point the outlet of the exhaust to the ground. Helps but the noise is still there.
Can't find anything on baffle numbers or configuration and how it affects noise. Quite a few references to packing them with fibrous matting but this isn't a long term solution. The quest continues!
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