[Roadsters] Choking [was: How to warm up a Roadster?]

[John F Sandhoff]

> Opening the choke does not lean out the mixture, it richens it.

> If you open the choke fully as soon as it's running and use the throttle
> to keep it running you are running lean (hot).

SU or Solex? :-)

The SU does not have a choke in the normal sense. The knob we
tug on is really a 'fuel enrichment' knob. In reality, nothing opens
or closes.

On a 'standard' carb such as a Solex, there's a physical air restrictor
plate that reduces the air admitted. Same fuel, less air = richer
mixture. "Closing" the choke richens the mixture by suffocating
air flow.

On an SU, pulling the "choke" knob drops the needle seat, effectively
opening the needle opening, increasing fuel flow. Air flow remains the
same.

Don't know if any of this helps the discussion...

-- John
     John F Sandhoff   sandhoff at csus.edu   Sacramento, CA