Demystifying Spridget/ SU carb choke operation

Here’s some hard-starting help!

We get frequent calls from people who have trouble starting their Bugeyes on cold days. There are lots of possible causes, but too often, incorrect choke operation is the culprit. The jets have to move or the choke will not enrich the mixture, which is required when the engine is cold. In the video below, I demonstrate what it looks like when the jets move during proper choke operation.

Sometimes the jets get gummy, they’re improperly adjusted, or the choke cable is worn, frayed or otherwise can’t operate the jets. We sell a nice reproduction of the original choke cable, which you can buy by clicking here. Another option is to upgrade the whole assembly and make it all new again (shown above). You’ll be impressed to see how nicely a new set of carbs actually works. You can purchase them here (and our kit also comes with a new manifold and heat shield, should you be upgrading from H1 carbs). HS2 carbs are a better design than the the original H1s that came with 948 engines on Mark 1 Sprites. Even the factory agreed that this was a smart upgrade, and fit these carbs on mark 2-948 cars. HS2 have a bigger throats too so you get more performance.

Regardless, check out the video below, I made it for a customer with hard-starting challenges, and I hope it helps you too!

Contact us at or call (203)-208-0980 during business hours