D28 B&B Side Draft Carburetor

[Aussie Don]

Gday All. I have a couple of question regarding a D28 B&B side draft carby.
I can’t see any size markings on the body, have measured the internals and have the following dimensions. Slide hole 0.920thou, outlet venturi is approximately 0.740thou and the mount spigot is 1”.
I made a new slide for it as the old one gas completely worn out.
# 1. Should the Slide fully uncover the venturi? Only opens 2/3 then hits the cap. The new ones is an accurate copy of the old of course. See photos for fully open and fully closed positions.
#2. Does anyone know what size the pilot jet size should be., I know they are sized by flow but I need a starting point. As you can see from the photos there was no idle jet just a needle?
 

[Odd Bob 66]

Hi Don.

Found this site useful for jet sizes and general info regarding B&B carbs:  https://www.barnstormers.co.nz/147/brown-barlow-carburettors-bb/

Slide not opening fully can't be right, as it may as well just have a smaller choke diameter. The B&B on my EW is vertical, but around the same size as yours, and the slide(s) definitely open all the way.

Cheers, Paul

[eddie]

Maybe someone, at some time, has fitted a slide from a different carb. A similar situation exists with later Amal carbs - the series 4 and 5 carbs have identical slides except the 5 slide is longer overall than the 4 slide, so wont give full throttle if fitted in a series 4 carb.

  Regards,
                Eddie.

[cardan]

#2. Does anyone know what size the pilot jet size should be.

The main jet was probably about 0.031".

Leon

[Aussie Don]

Thanks for the information, ill check out that B&B jet Data.