Boxerworks.com

The innards of the carbs and how they work are a big mystery to many, and simple to some.
How 'bout we clump lots of info in here, to unravel that mystique. I'd suggest we leave argie bargie re: tuning elsewhere, as we've done that to death.
Stuff relating to diaphragms, jets, floats, etc, etc, etc...snippets that have been gained over the years.
I'll start.

http://www.omnilex.com/public/bmw78/4.jpg
http://www.omnilex.com/public/bmw78/5.jpg

Kurt in S.A.

Gasp!

One of my subject dissected!

ME 109 wrote:Gasp!
One of my subject dissected!

Lord BING, your time is now!

SteveD wrote:Lord BING, your time is now!

I know who you are Lord MIKUNI!

We BINGS will defend our birthright to be next to the HEAD.

You have been trying to fuel this dispute for a long time!

It doesn't show any needle jet. Anything else they left out?

What is the port to the right of the needle jet?

ME 109 wrote:What is the port to the right of the needle jet?

Trying to put some spark into this thread....an overflow vent?? ...the long port that appears to go to the outside of the carb. See the flipped cutaway below...

The needle jet is above the main jet #3, below the needle #5, rather amateurishly represented here by me....



Here's a shot of the main jet and needle jet assembly. Main jet to the right, needle jet second from left.


I've flipped this pic to resemble the direction of the other diagrams....