TOPIC:

The ports on 1 - 3 are vents and ideally should have some tube on them looping downwards to prevent muck getting in.
The 4 yellow tubes from the float chambers to the brass fittings in the venturi look like a power jet set up for increase top end fueling but it's not clear from the pics.

Thank you Zed, and I believe that is correct on the four lines. Back in the late 1980's, I sent these carbs to be taper-bored, and an extra fuel circuit (power jet) was added also. That as you say only comes into play at full throttle-top end. They look to be some kind of pilot jet ?

Yes! they certainly do look like pilot jets that are being used in reverse.
The redundant holes in the pipe stub would have been the air bleed holes when used in their original application.
Obviously cheaper and easier to repurpose an existing mass produced jet rather than manufacture one offs.
I was going to ask if the carbs had been bored as I had a suspicion that those pipes were the 5th fuel circuit that Maxibore used to offer.

Interesting. Shouldn't there be some kind of check valve on each bowl?
Steve

My guess is that a check valve is not needed because the jet is in a place where there is very little velocity until the slide is fully open and the rpm (air flow) is really high.

That is wild...never seen that before.

Kind like the power valve at the bottom of my Motorcraft two barrel carb on my 69 F 250. At WOT it lets extra fuel enter the main circuit. I doubt it's needed on a street bike.
Very cool though.
Steve

Thank all you guys for your input, very helpful. And yes Zed it was Maxibore Co. in Southern California that I had sent them to. The memory banks are a bit hard to access after 30+ yr's. And yes the motor was built as a drag-race motor while keeping it street-able for back in the day. The last time that I raced it or even drove it was at Maui Raceway Park, mid 1990's. Gotta get her back on the pavement !!!