Larini valved rear boxes

[mjheathcote]

What's the physical difference between the valved and non valved rear boxes...is it just the addition of the valve on one of the pair of tail pipes?...so when closed the exhaust gases exit from one pipe only...and when open the exhaust gases exit from both pipes, hence louder?

I've purchased a pair of second hand non valved boxes, and was thinking about the possibility of making them valved.

I work for an engineering company, and we do stainless steel pipework fabrication so if I bought some valves it would be no problem to get them TIG welded into position.

A quick google indicates that electric exhaust butterfly valves are available. The pneumatic vacuum ones, how are they controlled on the GS or when retro fitted to the 4200? Where is the vacuum supply taken from?

Cheers
Mike

 

[Mr.Cambio]

on the GS they are controlled via the SPORT button. There is on the market a vacuum kit for making standard boxes, valved ones and it's powered by the cigarette lighter inside the cabin.

 

[rossyl]

Hi Mike
Did you get any further with this or manage to valve a 4200 exhaust?

 

[mjheathcote]

I phoned Larini and they informed me that the exhaust routing was different inside the box with the valved version and the non valved box could not be retro fitted.
Whether this information is true, or they simply didn't want to retro fit, or for me to retro fit with the information, I don't know.
Personally I can't see what difference they could be inside the box, there is no mechanical flaps inside, I just think if one outlet is closed, it is quieter!
I guess the easy way to tell is to shove a bit cork up one outlet on both sides and see if it is quieter!

 

[allandwf]

I think they're right, seem to remember a thread somewhere that showed the insides , I am sure it was routed through a small pipe and silencer material inside the back box when valve closed.

 

[rossyl]

Would be great if we could find thosepictures as maybe Mike might be able to get a few ideas and produce something?

 

[Fossy]

If your handy with a TIG torch, you can easily fabricate two like this. Its what i'm going to do, then wire it in to a relay sighted in the battery compartment, and connected to the signal wire from the sport button.

 

[lozcb]

Most of the valves are Vacuum operated and use a solenoid to open and close , there is a how to thread somewhere that shows quite clearly how they operate , where everything is located


regards loz

 

[VEDE]

Fossy, your design looks like the Kressieg system... i'll be keen to hear how it works out

 

[rossyl]

Is the bottom exhust stopped/allowed to flow by an electronic flap?

 

[lozcb]

Is the bottom exhust stopped/allowed to flow by an electronic flap?

the majority of exhaust valves are vacuum operated by an electric solenoid



regards loz