He's describing a common problem with saito radials that have a low run time jeff has given some good tips.Apart from setting the needles right,if that does'nt cure the problem then you can try adding 7 to 10% petrol to your glow mix.This will cure cylinder dropout at idle on the cheaper siedal seven and nine cylinder radials as well where you may get three or more cylinders dropping out at low rpm.Try it.