Sprint choke trouble

[series111]

For the last couple of years, I have been having trouble starting my sprint with the choke ( HS 6 SU's ) I pull the choke out fully and try to start the engine after a few cranks it will fire but will not run on the choke and I have to push the choke in, to keep it going I have to blip the throttle if I pull the choke out the engine just dies, once the engine is up to temperature the engine runs and drives nicely so today I had a look to see if anything is wrong, I could not see anything untoward, choke cable operates and the jets drop down the dampers go up and down the carbs nicely with no jamming there is oil in the dashpots and the throttle discs move a tiny bit ( how much should they open ).

Any Ideas would be welcome.

[Shaun]

I had similar issues with poor running on choke, rebuilt the carbs which improved things but still not quite right. Turned out to be air leaks on the carb mounts, purchased some of the clubs alloy mounts and now runs very well.
Are they properly balanced and set up?

[Carledo]

It's very possible that air leaks (name your source, there are several possibilities) have, over time, caused the carbs to be set excessively rich to compensate. thus rendering further enrichment by the choke redundant.

Try starting from cold with only enough choke on to engage the fast idle (about 1/4 choke) if it starts like this, it's safe to assume the basic tune is way on the rich side. Then it's time to go looking for the causes.

Steve