Is my middle carb missing a part?

Been fighting my 1977 Johnson Stinger 75 HP with a bogging problem for a while now. I've got a running 1977 Evinrude 70 HP that I've been swapping both ignition and gas parts with no luck (stator, timing base, power pack, carbs, fuel pump, gas tank, etc). Timing should be right, plates are set right, carbs are clean and float set right, etc. Spark jumps 2" gap on all three wires. Engine bored to 3.020 and rebuilt ... 125 psi on all three cylinders.

Last time out during WO bogging and the cover/air silencer removed, my partner looked into the carbs and noticed that the middle carb seemed to have too much fuel and the other two seemed to not have enough. When I got home and removed the carbs I noticed that the middle carb didn't have an extension [straw, pin, rod, restrictor, or whatever it's called] verticle piece to the ceiling like the other two. All pics I can find of other middle carbs seem to have this part. I'm not a carb expert, but I could see where if this piece is missing it might allow too much suction/fuel for it and rob the other two carbs. {When I temporarily swapped the Evinrude 70hp carbs last year it still bogged, but the part numbers are different}

So should my middle carb (387906) have this verticle through piece? If so, what is it called? I see where no kit or diagram refers to this piece! Thanx.

Re: Is my middle carb missing a part?

If this works, here's a pic of the middle carb compared with the top carb plus the rebuild.

Re: Is my middle carb missing a part?

It's missing the idle tube and you need a new carb body as it's part of it.

Re: Is my middle carb missing a part?

That sucks. The mystery missing part
Did the carbs sit a long time while it was being rebuilt? I'm guessing they were torn down during this process being the carb is missing a part? Make sure you have the jets in the right areas and not accidentally swapped around. I did that once on my stinger while cleaning the carbs. Just mixed them up on one carb and it would not rev without bogging down.

Re: Is my middle carb missing a part?

That part had to be missing before I bought it. I put carb kits in all three a couple of years ago, but I didn't take it out and I didn't know enough about it to have a red flag raised. I mostly didn't want to buy another carb for no reason. Thanks again.

Re: Is my middle carb missing a part?

Do your research. Look at Evinrudeparts.com. Check 2 years before, and after the year of your motor. Look at a Clymer manual for your motor, carbs were replaced under warranty some motors Clymers has pns of carbs. OMC service bulletin also has some info. The tube would screw out of some carbs.

Re: Is my middle carb missing a part?

I've got all the older marine manuals downloaded ... that's how I was able to break down the powerhead and rebuild it with new gaskets 2 years ago (last year the local lake closed down so no close-by testing). No doubt I've learned a lot by doing that, but there's still a lot to learn about it all.

I've got another middle carb on the way. What are the chances that this missing idle tube is the root of my bogging at wot? Fingers crossed!!!