HI Guys,

first off - congratulations on an excellent informative forum.

I have just picked a 1984 K100RT (non runner). The chap I bought it from said that his mate had looked at it and thought the ignition unit under the tank was faulty.

I have had a look at it and this is what I have done/found.
Cleaned all the earth points and changed the fuses
The starter will not turn over when pushing the start button
The fuel pump does not pressure up when the ignition switch on turned on
The fuel pump does work when the starter button is pressed.
If I earth the wire from the starter relay that goes up to the ignition unit plug the starter turns.
I pulled the lid off the starter relay and held the contacts together and the bike runs

Does this point towards the ignition unit or a wiring problem?

Any suggestions would be appreciated.
Geoff

After a quick look at the electrical schematic, I believe that the problem could be a simple as a bad emergency shut off switch. (The red On/Off switch under the starter button)

I'll have a look at it. It is a bit dodgy as it only powers the bike up when flicked to the right (off position). However it does switch the power off and on. I'll have another look at it and report my findings.

Geoff

In that case you should definitely follow the crazy amphibians hint :suspect:

Ok, I've done a bit more checking and I have switched power from the kill switch to pin 10 on the ignition unit and to the top fuse.
I also put a slave wire from the brown connector on the starter relay to earth. The starter motor works on the handlebar button now.
I still don't get the 2 second run on the fuel pump when I turn the ignition on. It does pump with the starter button pressed.
As the brown wire from the starter relay goes to the ignition unit, I am thinking that it is a defective unit. Would a defective ignition unit also cause the fuel pump not to pump for a couple of seconds when the ignition switch is turned on?

The fuel pump is running when you turn the ignition ON only on the 16 valves model. This doesn't apply to yours.

I get confused as I've had 5 BMW's over the years (all without electrical problems thank goodness). I think I'll source another ignition unit and give it a try. I'll let you know how I get on.