The HS needle is easier to get to and adjust than the LS one.

When you adjust the HS needle you are adjusting the main fuel flow point, which in turn tends to also modify the LS flow.

So if you richen the HS needle, you are also richening the LS flow as well.

That is why you are advised to set the HS first, then work on the LS when first tuning an engine.


I had a couple of engines where I did have to richen the HS out two to three clicks at the beginning of each flying day, to get them started.

Once warm, this was no longer needed.