One factor to getting a nice idle on your four stroke is finding the right plug. The nicest plug I ever found for my Saito 45 was the Champion VG-2. It's a 50's produced item, but you see them NOS on ebay fairly often and the price isn't much different from a modern premium plug. The VG-2's are quite hot, so the idle is excellent. And I think they must have been made before manufacturers learned how to make them more cheaply, because they seem to last forever.

Abu, if you can tolerate a 14" prop on your Snipe the greater diameter will make for a more reliable idle as well as a more efficent power transfer.

Dick