Took my refreshed 85 K100 out for a maiden voyage. All was super for twenty five miles, then crap.
The bike started running rough. As long as I stayed in low rpm it did ok. But put it under load and it appeared to be running on half the cylinders.
Limped home. It would start back up, but run poorly.
I let it sit for a few hours. Started fine, ran fine for a couple of miles and then crap.
I'm thinking bad coils (original black ones). Does this seem like a logical conclusion?
If the coils misbehave when hot, will a check of the ohms while cold reveal a problem?

The hall sensors are known to play up when hot, worth checking them (I don't know how, but others will)

As I was thinking.

POST FROM C.F.

Running poorly under load says coils to me as the Hall sensors tend to just stop working when the heat from the engine gets to them and then when cool will work fine. I would check the coils especially as they are the old grey type.

Just got back to town from trip on R850R. Starter problems urrrgh!

Thanks for replies.
Checked coils . I get 10.62 both front and back. 2.6 both front and back. I see that the old model coils run about there, with the newer ones in the 12-13 range. So it looks like the next stop is my ignition trigger (hall effect).
I have an 87 that I can pull one from and try on the 85. Will alignment be an issue going from one bike to the other, or is it only a matter of not putting it on 180 degrees out?
Also, with the LT will I need to undue the tank trimmings or can I possibly unhook the wire under the tank in a more clever way?

You cant get it 180° out because it is turning at crankshaft speed and if the V shape cut out and half moon cutaway are alligned all will be OK and within 1°.  Trust me I am NOT a politician.