The most common spring I replace is on the Briggs And Stratton Classic style engine. It is the longer of the two springs used called the governor spring
Genuine Briggs And Stratton Idle Governor Springs Briggs and Stratton Genuine 691859 Govenor Spring
The smaller governor spring is an Air Vane Governor Spring Briggs and Stratton Genuine 690254 Governor Spring
You can purchase starter recoil springs here Briggs and Stratton Genuine 491889 Spring Rewind Starter
Here’s a video showing how to replace the governor springs.
Please note all parts listed are personally picked and I have gone to the trouble of only selecting genuine parts where possible.
Leave me a comment on my Youtube channel if you can’t find a part. Just post your question in the comments section of any video and I will get back to you.
You can find my channel here https://www.youtube.com/c/MowerMan