Secondary Air Removal Plugs

So a friend with a lathe made these for me wouldn't let me make them)
View attachment Secondary Air Blockoff.bmp

He made them out of steel, but I suppose you could use aluminum if you want, but the originals were Steel.
Additionally he used 0.75 material so the over dimension of 0.785 is exact but 0.75 works great.
Be sure to use o-rings the same size as the Honda originals, I just ordered 4 new Honda parts.
It you choice as to the o-rings for the intake horns.
For me just a little grease made them slide right in to the heads ports.
As for the holes left in the intake box, the 3 screws used to hold the now removed Secondary box satisfactorily held with a tiny bit or RTV gasket placed on the threads while screwing in.
The BIG hole takes a 5/16 tap in the hole just fine, though the taper starts too big. Once tapped a bolt fits in real nicely and some RTV gasket material seals it fine.

Very nice! This is just what I wanted to see. I wonder if plastic or some composite materials might serve as well?

I've heard of someone making them out of plastic, but I don't know what kind. Why not just Aluminum or Steel. If you make it out of 3/4 material, you have only two cuts (not counting facind and cutting off). Seems pretty easy. Also I don't think its a big deal if you are a few thousands off.

And you could just cut the pipes off the originals and fill the holes with a metal filled epoxy (JB Weld for example)

I'm not good at caring for shine or steel. Most steel I have is already rusted. Thinking maybe brass or plastic.

Well Honda choose steel so I did. You could paint them black...

I used aluminum, not plastic, because those plugs are exposed to exhaust gas temperatures, I think.

If anyone wants it, I will attach a video of an engine running without the secondary air system (plugged). Seems OK.
:builder:

Pics are good and videos are better :yes:

Removing and correctly plugging the ports has no effect on running, performance or fuel economy. All it did was allow intake air (before carbs) to be pulled into the exhaust. Theoretically mixing air with the exhaust reduces the pollution. This is different that the Slow Air Valve which adds air to exhaust during certain vacuum conditions to allow unburnt gas mixture toi continue to burn thereby stopping backfiring during decelerating.

Plenty of vacuum leaks removed when I did mine!