Paul Goff http://www.norbsa02.freeuk.com/goffyelectrex.htm lists 5 ohm coils also.
As I always hate it when someone starts a thread and then never bothers to give any results, I thought I had better update my query about a pink spark. Timetravellers post about the variable gap spark tester reminded me that I too had one in my toolbox, so I conducted a series of tests with it. With and without suppressed plug caps, with kickstart or electric start, old ignition switch or a separate new switch, you can all imagine the permutations. The end result was that one of my coils was consistently weaker than the other in every test. I have accordingly ordered two new high performance coils. When they arrive, a new series of tests will be carried out. Watch this space.....
Paul Goff http://www.norbsa02.freeuk.com/goffyelectrex.htm lists 5 ohm coils also.
I am a great advocate of generous heat sinks fitted to both ends of any Jap type coil. Certainly the old Lucas Rita system mis-firing was cured with these objects.
Cheers, ET43