Anyone know what this is? Cat Valve

[Shaft]

I posted this pic in my 'show & tell' moped project thread, but I wondered if I might get a better response here:

https://img69.imageshack.us/img69/3286/artycopy.jpg


I have very little experience with modern bikes in general and scooters in particular, so this has got me stumped.

The armoured hose appears to run to the airbox, so I'm guessing it's some kind of emissions gubbins, but there's no electrical connections, so whatever is in that box must be heat/pressure operated.

I was planning on changing the exhaust, but would removing this alter the way the bike runs and what would I do to rectify it?

Sorry if I'm asking the bleeding obvious, but I've not come across anything like this before.
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[Fisty]

Its a very rare platinum powerband.
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[Shaft]

Ho bloody ho
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Things get better with age; I'm close to being magnificent........
20 RE Interceptor, 83 Z1100A3, 83 GS650 Katana
WooHoo, I'm a Man Point Millionaire! https://www.bikechatforums.com/viewtopic.php?t=234035

[heehaw]

well, it was...
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Retro Rider Bicycles: CB125TDC, CBR400RR, BSA Bantam.

[Shaft]

Eh?


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Things get better with age; I'm close to being magnificent........
20 RE Interceptor, 83 Z1100A3, 83 GS650 Katana
WooHoo, I'm a Man Point Millionaire! https://www.bikechatforums.com/viewtopic.php?t=234035

[N cee thirty]

it might be a emmissions thing that sends cool air from the airbox in to the exhaust to lean it out abit

the box probs has some sort of diapram in
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[Shaft]

[Pete.]

It's a valve for pumping fresh air out of the airbox into the exhaust to supply oxygen for burning off any un-spent fuel. Has no effect on engine performance.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Shaft]

Thanks for the explanation Pete, the only thing I've seen like it is on old Yank car engines, where they used to fit all sorts of Heath Robinson contraptions, usually with devastating effects on performance.

If there's that much fuel in there, I might tap it for a spark plug
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Things get better with age; I'm close to being magnificent........
20 RE Interceptor, 83 Z1100A3, 83 GS650 Katana
WooHoo, I'm a Man Point Millionaire! https://www.bikechatforums.com/viewtopic.php?t=234035

[stinkwheel]

Aye. Also called a passive air valve. Bleeds air into the exhaust to reduce emissions.

They sometimes have a vacuum takeoff from the carb to open and shut the valve. Remember to blank this off if you remove it or you'll run lean.
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