I have a problem with my XJ 750. The plugs are all totally sooted up in 100 miles.

I got to thinking that it is the coils. The manual says that I should get about 13K ohms across the secondary winding (plugs 1&4 2&3). I am gettng 22K ohms but 13 without the caps.

so my question is, although the diagram in the manual shows with caps, should I measure with or with out them?

I am getting 4K ohms through each cap alone. Should I try to get non-resistored caps or are my coils breaking down or am I barking up the wrong tree?

I always read it as without caps.

caps come in two flavours 5 ohms and 10 ihms. the 10 ohms give a weaker but longer spark, with the 5k strong but short, depends on the bike specs really.

Thanks Drewpy. Looks like my problem isnt my coils then. The HT leads were heavily oxidised where the cap screwed in. Cutting them back did help a little.