Author Topic: Exhaust Rapping  (Read 745 times)

Offline Yasser

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Re: Exhaust Rapping
« Reply #15 on: 15.09. 2020 17:00 »
Hello everyone.

I really appreciate your fast and sincere anwers. In Spanish we have a say "For different tastes, different colors" maybe that's why I love this sound...

20 years ago, I was ridding a two stroke motorcycle. This sound I am describing your made me fall in love, and it was produced by a Road Rocket BSA.

Unfortunately I could never get one of this, but a Norton Dominator. And after years I also love my Norton, but my heart still love this sound.

I Cuba there is no need to care about this loud sound, if you like it you can go with it.

The red light is what we call chisperos. Have you every had a fouling plug? Try to put the high tension cable some mm far, it will make the spark stronger and maybe your plug will come back to work. Let say this is a "professional" chispero. My friend installs it just for fun.

So. After all explanations. Do you think that making an insertion at the end of the exhaust that reduces the diameter by some mm I should get more air speed in order to make the O2 reach the hot zone of the exhaust and them explode?
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Online Greybeard

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Re: Exhaust Rapping
« Reply #16 on: 15.09. 2020 19:29 »
The red light is what we call chisperos. Have you every had a fouling plug? Try to put the high tension cable some mm far, it will make the spark stronger and maybe your plug will come back to work. Let say this is a "professional" chispero. My friend installs it just for fun.
*doubt*
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Online RDfella

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Re: Exhaust Rapping
« Reply #17 on: 15.09. 2020 19:36 »
Reminiscent of the Norton 'spark intensifier'. Have one in my spares drawer.
Reminds me of many decades ago when I was working in a garage. One of our customers had 50's Bedford trucks and those models would foul plugs if left idling for any time. One of their trucks was particularly bad, so I cut all the HT leads and inserted buttons from old overalls in such fashion that the spark had to jump across the button centre. Worked a treat, but the boss was none too delighted when one day he lifted the bonnet and saw what looked like a firework display. I pointed out that it worked so he closed the bonnet and walked away.
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Online RichardL

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Re: Exhaust Rapping
« Reply #18 on: 15.09. 2020 22:29 »
So, TT, would you call it a good thing, a bad thing, or harmless fun?

Richard L.
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Offline Yasser

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Re: Exhaust Rapping
« Reply #19 on: 16.09. 2020 15:08 »
No harm at all, it is useful. This is wide used on two strokes machines, where gas is contaminated with oil, lowering is combusting properties. Of course, with todays high tension coils, electronic ignition systems and platinum point spark plugs there is no need of it. So if you use a Boyer Bransden or so, forget about it....if you have an original Lucas magneto it will help for sure....

Now...

Back to the topic.

Yesterday I made my final test..

I reduced the end of the exhaust pipe...the result was a killer DB with a kind of whistling sound..SO, I started testing lengh from let say 30 inches of overall lenght until I get the rear axle and BUM....there is a point where the rapping is very loud and deep...

My conclusion..

Depending on your compresion, and cam and carb...there is a moment where unburned gasoline is trapped between the head and the first part of the exhaust pipe...the correct lenght of the pipe will make a return source of fresh oxigen reach this "dust of gas" that is actually very hot...So combustible+oxidizing+temperature BOOM, an explotion happens in the pipes and is amplified by the pipe itself.

So I am very happy with the result. Now I can ride smiling with my BSA fellow!!!

Thank you so much for your support.

All the best

P.D Triton Trasher, you nailed it!!! Thank you so much
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Offline Zander

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Re: Exhaust Rapping
« Reply #20 on: 16.09. 2020 15:54 »
Can’t say I’m keen on wrapping, but each to his own.  I consider my Gold Flash to be a bit loud and reckon the pipes are straight through, so has anyone had success in repacking silencers? TIA.
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Offline mugwump

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Re: Exhaust Rapping
« Reply #21 on: 16.09. 2020 17:21 »
Whers's your youthful spirit George *smile* *smile*. I have a reverse cone mega on my ariel and it sounds great.
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Offline Zander

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Re: Exhaust Rapping
« Reply #22 on: 16.09. 2020 18:26 »
My 15 year old youthful spirit is still in the bottle, John *smile*
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Online muskrat

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Re: Exhaust Rapping
« Reply #23 on: 16.09. 2020 21:33 »
G'day Yasser.
I've been away for a few days.
My A10 Cafe sounds very similar. I love the sound when backing off and going down through the gears for a red light. Mine is a combination of big carbs, big valves, 357 cam and reverse cone megas. There is nothing inside from the exhaust valve to the end of the pipe.
A saying down here is "loud pipes save lives"
Cheers
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Offline Yasser

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Re: Exhaust Rapping
« Reply #24 on: 17.09. 2020 12:04 »
Mr. Brown Muskrat

Can you share this sound?
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Online groily

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Re: Exhaust Rapping
« Reply #25 on: 17.09. 2020 16:51 »
"loud pipes save lives"
With you on that one Musky! . . . Even if it's a bit hard on the ears of anyone too close behind!
Like most things round here, owner included, the beast in the pic needs a bit of a clean - but the Big Black Hole is fun, and living in the sticks it doesn't upset anyone else. I'm not really an anti-social sort of barsteward, but I do like to hear where I'm going.
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Online RichardL

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Re: Exhaust Rapping
« Reply #26 on: 17.09. 2020 18:17 »
My stock silencers aren't particularly loud, but as an aging audio guy, I protect my remaining hearing when I can, so I often wear earplugs when I ride.

Richard L.
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Online Greybeard

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Re: Exhaust Rapping
« Reply #27 on: 17.09. 2020 18:20 »
I have standard looking cigar shaped replacement silencers. They have a nice sound. I don't think there is very much baffling inside. They don't have that over-run crackle though.
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Online metalflake11

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Re: Exhaust Rapping
« Reply #28 on: 17.09. 2020 21:13 »
Only straight through will do.

Get the air in, blow it up, and get shut as soon as possible without any messing about.

They're not that loud anyway burbling about in town, and on the motorways and A roads there's no one to annoy.
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Offline Jules

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Re: Exhaust Rapping
« Reply #29 on: 18.09. 2020 02:23 »
You guys sound like you need a Harley without silencers, or maybe that is your "other" bike LOL  *smile*, where I live they come "cracking" through the hills every weekend, not a good sound IMO, the standard Harley sound is good (and patented!), while the open exhaust "crack" is way too offensive.....
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