@maxtenet:
I had the old Raduga 7M running with 80/20 FAI Fuel this wasn't the problem, even with hand starting (since I had no starter to this time).
The russian plugs are proven to be good, that can't be the problem. The engine should run as it is but they came with an speed carb, no RC Carb like this on the picture above. I think Paulinos Engine is set heavily to fat at idle.

@earl: The russian engines from this time came with instructions that don't even mentioned nitromethane, this stuff wasn't easy to get in east germany and as far as I know in the USSR.

Regards,

Holm