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Offline Belco100

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Second Pipe
« on: October 03, 2020, 05:07:07 PM »
What is that second, smaller pipe for that goes into the silencer? Does it actually do anything?

Offline smithy

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Re: Second Pipe
« Reply #1 on: October 03, 2020, 09:57:44 PM »
*Originally Posted by Belco100 [+]
What is that second, smaller pipe for that goes into the silencer? Does it actually do anything?

All the exhaust gas goes throught it....until the flapper valve opens at ~5-6000rpm , then the gasses go through both. It's a noise pollution thing. Just disconnect the cables and the valve will be open all the time.

Smithy.
« Last Edit: October 03, 2020, 09:58:55 PM by smithy »
When I die, I want to go peacefully in my sleep like my Grandfather....not screaming like the passengers in his car..!

Offline Winger

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Re: Second Pipe
« Reply #2 on: October 04, 2020, 11:45:12 AM »
What folks need to understand poor old BM and all the other bike manufacturers have one arm tied behind their back because of the TUV insisting on both noise and exhaust pollution, as private punters we do not and there’s a whole new world of extra engine performance for those that want it, hence why it will take years for a stock production bike to match what the like of what Smithy and I have now, in fact my money is on BM having to go big bore in the end to matching current engine performance with increasing TUV restrictions.
« Last Edit: October 04, 2020, 12:12:23 PM by Winger »

Online Crosshairs

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Re: Second Pipe
« Reply #3 on: October 04, 2020, 01:04:26 PM »
I would assume it also helps a bit with low end power so leaving it open all the time may not the best idea ....
Or is the cat plenty of back pressure and the valve really is just for noise? ...has anyone done any testing on this ?

Offline Belco100

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Re: Second Pipe
« Reply #4 on: October 04, 2020, 04:38:29 PM »
I doubt if it’s for back pressure, likely to be just noise. Had a similar thing on my 1250GSA, and when I had the ECU flashed one of the things done was to open it up immediately and that worked on the Dyno. Just wondered why all of the S models had the funny second pipe, quite unusual.

Offline orbits

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Re: Second Pipe
« Reply #5 on: October 04, 2020, 07:04:09 PM »
Just curious but what gains can can legally (UK roads) be achieved these days?

I ask as it’s probably 15 years since I did any serious engine / exhaust modding and my carry-over assumption from back then is that once you deviate to a non ‘e’marked can, remove noise baffles, start removing Cat etc then you drift in to the territory of a bike that won’t pass a MOT (friendly testers aside).

Not trying to sound like a wet blanket; I like the gains, but I can’t be faffed with swapping standard kit back again just to pass a MOT, or putting myself in a grey area if I get stopped.

Can you do a ‘worthwhile’ can/fuelling mod to the XR that’s still road legal?  Ta.
« Last Edit: October 04, 2020, 07:05:58 PM by orbits »

Offline Winger

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Re: Second Pipe
« Reply #6 on: October 04, 2020, 07:50:10 PM »
Fair enough questions and technically you are correct about having to swap over for the MOT, it’s also illegal to speed but it doesn’t stop people doing it does it?

If you read the small print...the moment the bike is off the MOT premises the test doesn’t mean a dam thing, Never had the slightest problem having any of mine tested and non of them are remotely stock.

It’s already been said but headers/end can/PC or Rapidbike takes the bike to another level, but important bit...if you can’t twirl a spanner do not attempt to take off and fit the headers yourself it’s a ball ache.

But if you do 12 sided socket for the headers nuts is the best tip I had.

Offline CNC-REPAIRS

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Re: Second Pipe
« Reply #7 on: October 06, 2020, 08:17:43 PM »
I’ve put a full arrow system with titanium end can I keep the baffle in as I don’t want too much noise on mine.The weight saving is ridiculous. I really enjoyed fitting the system it can be awkward and if your not good with spanner's don’t start it!!  After I fitted the system my bike ran like an absolute piece of sh#t. The vibrations through the bars were ridiculous and low end and mid range were terrible. After ECU work the vibrations had gone mid range is amazing. Completely different bike and well worth it.  Also it sailed through the MOT without change. the end can Is road legal stamped although I do believe this is only applicable when on the standard headers
« Last Edit: October 06, 2020, 08:22:34 PM by CNC-REPAIRS »

 



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