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Post by fenz on Oct 2, 2007 0:51:12 GMT -5
Starting to think about a megaphone muffler for my track bike.
Does any one out there have a tried and tested design???
I have a long slim tapered muffler that came from an xs250 (i think )and i was going to cut this up and attach a reverse cone to the end.
Header will be long swept down type with the reverse meg mounted at a pre determined length.
Bike is going to be used for track days (non competition) so hopefully noise wont be an issue.
Looking to make the pipe as light as possable so trying to stay away from a baffled/packed style exhaust.
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Post by curly001 on Oct 2, 2007 5:27:54 GMT -5
Fenz,
You need to speak with wizz954(Rick) he runs a reverse cone on his SR track bike.
Curly
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Post by wizz954 on Oct 2, 2007 7:40:51 GMT -5
Reverse mega works pretty well, but very noisy. Someone put a noisemeter on the end of mine and at 4000rpm it was reading 118DB. I'm sure this was not a legitimate way of testing/measuring but it's definitely one of the loudest bikes out there now.
Mine is straight through pipe without baffling of any sort. Depends on whether the pipe you have is straight through or baffled whether a reverse cone might help or not.
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Post by fenz on Oct 2, 2007 16:12:23 GMT -5
Pipe will be straight through.I will post a pick of what i have got soon as i dig it out of the parts bin.
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Post by colinjay on Oct 2, 2007 17:28:01 GMT -5
Fenz,
I have made some reverse cone megaphones over the years and have some patterns for them. HOWEVER, I doubt very much that any open megaphone would pass the current MA noise test which has a max limit of 102dB and is set to drop to 96dB as of Jan 1st 2008. I would recomend that you might as well setup a small supertrapp muffler that is tunable, as that way you make it a bit quiter if the noise nazi get you.
CJ
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Post by colinjay on Oct 2, 2007 17:30:23 GMT -5
I forgot to add in the above post, that most trackdays organisers have to abide by noise restrictions/limits and generally use the MA rules as their reference.
CJ
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Post by wizz954 on Oct 3, 2007 7:23:41 GMT -5
Yeah, I've been reading about the new noise levels on the PCRA forum and I don't see how any race bike will pass the new test. I will have a small problem quietening mine up.  |
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Post by milkman on Oct 3, 2007 10:15:35 GMT -5
What did you rate on the weekend Rick, 118 db?
Thats a fair amount of muffling needed.
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Post by fenz on Oct 3, 2007 18:21:23 GMT -5
Might have a talk to my local muffler shop guy and get some perf tube to run through the guts of it with glass packing around the tube.
Should be able to sort something as he is into bikes also.
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Post by wizz954 on Oct 4, 2007 6:04:44 GMT -5
Mine will take a lot of muffling, even taking the noise reading properly would still be up there, I'd say. My pipe used to have a muffler on the end of the reverse cone, until it was "removed" after getting squished at Eastern Creek in March, then it became an eyesore..
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Post by colinjay on Oct 4, 2007 17:25:20 GMT -5
Fenz, I had a look thru my shed and found one of the old reverse cone megaphone that I made back in the days of my anti-social past, see pic below.  Basic dimensions are; overall length 240mm, max diameter 100mm, outlet diameter 80mm. I used to run one of these on my SR on the road, and it sounded brilliant, however, it was VERY LOUD! You can add a muffler section onto the end of the megaphone which would quiten it down a bit, but it would still be LOUD. If you PM me your postal address I will post you a set of paper templates that will let you make up the cones for the megaphone. CJ |
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Post by fenz on Oct 5, 2007 0:01:58 GMT -5
Hell it sounds loud just looking at it.Will PM you postal address..
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Post by caferacercarl on Dec 3, 2007 2:40:18 GMT -5
With the bore/stroke ratio of the SR,and the cam timing lobe centres, they always perform better with a perf core muffler [ stainless washing up thingies for packing] and step up the diametres in the direction of flow, all Dyno proven, Madaz in melbourne will make you up a lovely muffler if you want. regards Carl, [never use a supertrap]
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Post by milkman on Dec 3, 2007 3:24:41 GMT -5
Never use a Supertrapp?
I was just about to, no good?
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Post by curly001 on Dec 3, 2007 3:47:40 GMT -5
Don't panic milko! If you don't want it I understand. But it got a perforated core. That's why I brought it.
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