Topic: 1981 CB650 Fuel leak

[MaxwellTheMalinois]

Been plaguing my brain after doing a rebuild of my carburetors and fuel seems to be leaking out of the rear reference holes. The video shows what's going on. I'm aware the vacuum line on the automatic petcock aren't correct, however even with them in the correct position the carburetors still leak. I've tried just about all I can think of. I'm not knowledgeable with these. I've never had any problems with carburetors like this before. The carburetors are VB44A with the automatic petcock. No idea what exactly is the culprit. Unless there's supposed to be a little black rubber plug in the bowls in one of the 3 holes. Otherwise I'm stumped and out of ideas.
https://youtube.com/shorts/zQhVPKqywYw?feature=share
Link to the video.

[newday777]

Welcome to the forum Maxwell
Did you put in aftermarket float valves in the carbs?

[MaxwellTheMalinois]

I did as my original ones had been messed with. But the issue was happening with the original ones too.

[fizzlebottom]

I suspect floats or float valves. If you have aftermarket floats, put the originals back in if they're still in spec or replace with new expensive ones from Honda if the originals are not in spec. Aftermarket float valves are mostly fine in these carbs as they're rubber tipped. I've never had problems with them, but that's just me. They do require clean and undamaged seats though, so make sure your seats are both clean and undamaged.

The last thing is you 100% should remove that vacuum petcock. It isn't going to fix your leaks, but it will cause headaches down the line. There is a diaphragm inside which is completely out of production, out of stock, and not a single aftermarket producer makes. If it is damaged, it is done for. Get rid of it now and never worry about it again.

[MaxwellTheMalinois]

I wanna get rid of the vacuum shutoff, the seats are clean and undamaged. I got basic OEM style replacement. But would the adjustable ones be worth it? Cause I think it's just the lack of adjustment. Unless you have a link to the floats from Honda.

[scottly]

Been plaguing my brain after doing a rebuild of my carburetors and fuel seems to be leaking out of the rear reference holes.

I believe those "rear reference holes" are actually the accelerator pump discharge nozzles? Did you do anything with the pump during the rebuild?

[MaxwellTheMalinois]

The accelerator pump goes through the little brass fittings poking from the front of the carb throat.

[MaxwellTheMalinois]

It's leaking from the hole above the choke shaft

[scottly]

It's leaking from the hole above the choke shaft

Thanks for pointing that out; it's hard to see from the camera angle. Do a "clear tube" test, which will show if the fuel level is too high in the float bowls. If it is too high, there must be a problem with the floats or float needles/seats.

[MaxwellTheMalinois]

Could you get an example video of that? I've never done it.

[scottly]

 Basically, you attach a piece of clear tubing to the float bowl drain, and hold it next to the carb body. The fuel level should be about 3 mm below the seam where the bowl meets the carb body. Reply #320 in this thread will give you an idea how it's done.
http://forums.sohc4.net/index.php/topic,82012.msg2219234.html#msg2219234