So to avoid small amount of water pooling around my exhaust valve (slight reversion because of the cam) I want a way to bypass the exhaust risers and instead dump water through the transom on command. For example, after idling for a long while on my way back to the launch, before docking I can switch from water cooling the exhaust to bypassing it, let it idle for a minute or 2 maybe rev once or twice to clear water out, then shut down the engine so no water is being left in the exhaust port until the next weekend.
Has anyone done this? I was thinking a system of 2 diverting valves, one in each manifold hose that once switched would shut off water to the exhaust, and send it through a transom dump. I can't seem to find a 12v electric valve like I'm imagining however.
I want to hear your thoughts

What kind of exhaust do you have now?

X2

Everything stock including exhaust? I see where your coming from however I'd think seriously about a different cam or two if twins. The slightest little bit cold Lake Huron water on a hot exhaust valve can turn a picnic turn into a really bad day. Just a thought.

I don't know how long any rubber component in the exhaust system could run dry before burning up. I would think it would be less than minutes.
Are you getting condensation?

Current exhaust is EMI thunder with silent choice risers, there really isn't so much a reversion problem as a moisture problem really. The whole inside of the manifold is just wet, and a little pools at the bottom.

I wouldn't be running anything dry, except the exhaust. All water into the engine exits through the exhaust, my idea would be to bypass that circuit by flipping a switch and dumping water out the transom instead, just to clear the exhaust before shutting down for a while.

I wish a flip of the switch could solve all my problems. Good luck with all that.

You MUST run water through your exhaust 100% of the time. Even dry exhaust systems have water running through them 100% of the time. The water is still flowing between the inside and outside walls. What you are proposing doing is fire hazard. You should just get longer risers and ditch the silent choice or switch cams.

Shutting water off to the exhaust for 30 seconds at idle will not cause any fire hazard...

It may be easier to just drain the exhaust after shut down, you could plumb in 12V solenoid to do this, even if you divert the water away from the exhaust dump it will still be hiding some. Granted it will warm up and reduce the condensation but the rubber connectors in the system will suffer every time it is dry even for a short period.