Author Topic: Exhaust Rapping  (Read 950 times)

Online Jules

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Re: Exhaust Rapping
« Reply #45 on: 22.09. 2020 12:53 »
Good looking (the bike not you Musky ha ha), and the sound is very amenable actually, I thought the starting was very good too for the level of tune Musky, well worth the effort of showing, thanks

Online metalflake11

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Re: Exhaust Rapping
« Reply #46 on: 22.09. 2020 14:37 »
I've had a go on Youtube now as well!  *smile*

Straight through pipes....... I did this video 6/7 years ago, to show somebody how the Sparkbright digital voltmeter works, and the charging light behind the carb. People often comment how quiet it is for straight through pipes, but around 70/80mph it sounds 'slightly' different.

 It has 24 (yes four) teeth on the engine, and 21 on the gearbox so it lopes along on the motorway where a lot of my mileage is covered.

https://www.youtube.com/watch?v=i0F54EIHtqo&t=55s
England N.W
1960 A10
England

Online Black Sheep

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Re: Exhaust Rapping
« Reply #47 on: 22.09. 2020 15:28 »
The exhaust note depends on resonance so is affected by the length of the pipe and rpm and of course the silencer/megaphone/trunpet if any fitted. As we all know valve overlap and pressure pulses in the exhaust result in increased cylinder filling at a specific rpm with the effect reducing and eventually reversed away from that rpm. You have a similar effect on the inlet side of course. Anyway, there is a sweet rpm for any engine which will sound good (depends on your definition of good) and there is another where it sounds pretty rough. An example is the Manx Norton which comes on cam rather sharply at 5,200 rpm and at 3,500 rpm is pretty gutless and sounds dreadful. 
2 twins, 2 singles, lots of sheep

Offline Yasser

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Re: Exhaust Rapping
« Reply #48 on: 22.09. 2020 18:02 »
I haven't  seen any engine doing so much rap than the orinaly posted BSA in Cuba. I am convinced there is a trick behind it that the owner knows very well and worked on it to make it easier.

Offline muskrat

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Re: Exhaust Rapping
« Reply #49 on: 22.09. 2020 20:49 »
G'day MF11. Sounds very nice. Now I need to see a vid out in the light of day.
 
G'day BS. Your right of course, my pipes were tuned to the A7SS for 6500rpm. The 357 cam comes in at about 4500. I only took her up to 4000 in the video, we know what happened last time I revved her up to 7000 in neutral  *pull hair out* *bash* *work*. For those that missed it https://www.a7a10.net/forum/index.php?topic=10630.msg79189#msg79189
 
G'day Yasser, yes the one in your video sounds a lot crisper. Open mega's help but it'd probably suffer megaphoneitis till it got on the cam

Ha, just noticed I was wearing the forum Tee shirt and the print on the wall. Now I'm in trouble for wearing a good shirt in the shed.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline Yasser

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Re: Exhaust Rapping
« Reply #50 on: 30.10. 2020 18:01 »
Check out this video and you will understand better

https://youtu.be/9NhtF7A1LZY


Online Jules

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Re: Exhaust Rapping
« Reply #51 on: 31.10. 2020 09:32 »
interesting video Yasser, thanks - spoilt by the rapping exhaust though LOL, sorry  *shh*

Offline olev

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Re: Exhaust Rapping
« Reply #52 on: 01.11. 2020 03:32 »
Gday Yasser,
What sort of bike is that in your latest video?
It can't be a BSA - its not shaking enough.
and you can actually see things in the rear view mirror.
cheers

Offline Yasser

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Re: Exhaust Rapping
« Reply #53 on: 01.11. 2020 13:56 »
The camera is over a Norton Dominator 99 but the rapper is a BSA Golden Flash with a 357 cam