Carb setup
 

I have an old OS 40 SR that I want to put in a SIG Kougar. Does anyone have any suggestions for initial carb setup?

There is a screw in the center of the throttle arm/barrell. I loosened it thinking that I could change the position of the throttle arm, like on my 40 LA, then I realized that it is an air bleed or low idle adjustment or some such thing. I did not keep track of how many turns I backed it out.

This engine looks new, looks like it has not been run, great compression. I am told it was a hot engine for it's time. It is a ringed 2 stroke.

Carb setup
 

That IS a great engine. Try turning the screw all the way in, then back it out 2 turns. You'll still have to adjust it once it's running, but that should get you going.

Carb setup
 

Thanks for the info!

Is it a low idle screw? What is its function?

Carb setup
 

It is a low idle mixture screw. Low idle screws are very sensitive, so when you set the engine up, turn it just a little bit at a time.

Carb setup
 

yup