Author Topic: D28 B&B Side Draft Carburetor  (Read 382 times)

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Offline Aussie Don

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D28 B&B Side Draft Carburetor
« on: 28 Nov 2021 at 09:44 »
Gday All. I have a couple of question regarding a D28 B&B side draft carby.
I canít 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 1Ē.
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?
 

Offline Odd Bob 66

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Re: D28 B&B Side Draft Carburetor
« Reply #1 on: 28 Nov 2021 at 20:21 »
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

Online eddie

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Re: D28 B&B Side Draft Carburetor
« Reply #2 on: 29 Nov 2021 at 10:15 »
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.

Offline cardan

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Re: D28 B&B Side Draft Carburetor
« Reply #3 on: 29 Nov 2021 at 22:59 »
#2. Does anyone know what size the pilot jet size should be.
The main jet was probably about 0.031".

Leon

Offline Aussie Don

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Re: D28 B&B Side Draft Carburetor
« Reply #4 on: 01 Dec 2021 at 00:24 »
Thanks for the information, ill check out that B&B jet Data.