Making it a bit louder

[Dom]

I'd like to improve the exhaust note of my 650B running standard exhausts. I quite like the standard look, so I'd prefer not to mess with what is a fairly rare exhaust but if I swapped the silencer for louder ones I presume I'll definitely require a re-tune? I was thinking it would be great to have them interchangeable

 

[5twins]

Maybe, maybe not. The earlier carb sets were set up richer so you might get away with just one little change like this (I assume you're keeping the stock airbox and filters?) and not have to re-jet. And even if you did, I don't think it would require much of a change, maybe bump the mains up one size. But probably the only way to really tell would be to try it.

 

[Dom]

It came to me with generic non K&N pleated cones but I've got Ramair Pod filters to replace them because they look very small and restrictive. I'm expecting I'll need to do a bit of tweaking

 

[Grewth]

A bit of a black art TBH.
Not like changing the pipes or filters on a modern sportsbike, where a quick search online will give you jet sizes etc, or even point you towards a dedicated jetting kit.
You've got a 47 Y.O. museum piece that wasn't even designed to run on modern fuel.
The 650 was considerably detuned for 1974, due to increasingly restrictive noise and emissions regulations.
So the silencers got bigger and quieter, along with new air boxes and a softer camshaft.
Replace the silencers with something less restrictive, and hopefully you'll gain a couple of horses, but the carbs will most likely need jetting.

 

[WideAWAKE]

The noice level of an exhaust doesn’t contribute to the jetting needed by the carburetor to properly run.

If they flow better (and your swapping from a pleated to foam filter) most likely you’ll need to increase your jetting.

As 5twins said, probably just a small bump.

 

[Dom]

I'll consider keeping my original silencers safe and going to something slightly shorter and less restricted I think.