Exhaust flapper valve??

[wayne]

This is not from an early model but possibly a one-off or limited production as the original owner was an "anointed" one among people in the Suzuki business (not a Board member unfortunately).

I have sectioned a pipe in the past and not seen any evidence of this valve. But here it is. Deep inside the inner stainless pipe, on the top and approximately below where the passenger foot peg is. See link below for photos of a sectioned pipe:




SECTIONED EXHAUST

[Framitron]

Very interesting. How is it actuated? Gas pressure?

[wayne]

It seems to have no spring tension, just held by its own weight. Presumably at lower rpm the exhaust flows through the baffles and as gas pressure rises, the flap is lifted allowing a certain amount of bypass and less restrictive flow.

More HP? I know some modern bikes (VFR1200) had a flapper valve at the end of the exhaust but I believe it was more for noise/power balance. At lower city street rpm the bike was fairly quiet but when you gave it a fistfull, the flapper opened at the tail of the exhaust- more power, more noise but presumably you're not in the local cul-de-sac.