Hi. I’m Geoff. from Sleaford, Lincolnshire. England.
I have a 1987 K100RS that I have owned for a couple of years. I bought it to do a trip to the Picos Mountains in Spain and it ran faultlessly.
I now have an ignition issue that I am hoping to get some technical help to solve.

 Geoff, just ask away tell us how handy you are with the spanners

Hi guys.
Sorry for the delay in responding, been away.
My ignition problem.
After riding about 15 miles bike went onto two cylinders. Limped home and found that plugs 1&4 ok 2&3 wet. Checked wiring diagram and saw that ignition coils are paired so removed appropriate coil and found the casing to be burnt at the bottom and residue from the windings leaking out.
Replaced the coil but still running on two cylinders. Tried two other coils in case replacement was faulty but still no spark. Checked the power supply to both coils and that was ok so now assuming that the problem is further back up the line which could either be the ignition control unit or the ignition trigger unit.
Having had a couple of horizontal twins in the past I remember from the forums that Hall Effect Sensors were often a problem and after researching this further it appears that the poor quality wiring used on the HES ‘s was more of a problem than the sensors.
Any help in tracing the source my problem would be gratefully received. As a retired engineer I am quite happy to carry out any work but when it comes to electronics I get baffled and very frustrated.