one or two petcocks?

Joe...I got the same setup...aluminum plate in the back of the tank. I drilled it and tapped it for a 3/8 pipe thread...then threaded in a barbed adapter....3/8 pipe on one end...various barb sizes available for the other end. McMaster has them.

Be warned...the drilling can be tricky...3/8" pipe thread requires about a 5/8" hole. And that can get kind of nasty. I thought for sure it would rip the metal plate out of the tank...but the tannermatic tank took it just fine.

You could probably get away with smaller than 3/8 easily. Not sure why I went that large. Remember to clean the shavings out of the tank.
JohnnyB

I use the middle one...have it on a couple of bikes. Pretty nice quality too.
Not sure about the whole 200cc rating...I've seen that in the catalogs but the day my 200 can use all the fuel that can run out of this thing I'll be a happy man. Hell the passages are larger than the inlets on the OEM petcock.
I've used them to drain my tanks before leaving that track, can drain out a gallon in a few minutes...that should be enough for most bikes. Maybe they meant a 200cc two stroke?
Anyway...not sure if they still come that way but the ones I've bought almost exactly like the one in the middle except they have a mount like a toggle switch...put it through a hole and tighten down a nut. The quality is surprising...the one on the left...piece of crap, I've tried them too.
JohnnyB

Frank...maybe I've never gotten the right ones but whenever I use those quick disconnects, after a couple times on and off they are a real bitch to plug in and pull part. I used to have to keep putting grease on them.
JohnnyB

Roger.

JohnnyB