So the battery has some capacity, have you ever left the battery in the bike for a few days but not connected, was the battery still charged when you reconnected it. You said earlier in your post that your charger would not work while the battery was still connected? Something to do while you wait for the battery to charge, measur the resistance between the battery +ve lead and chassis, no battery connected, should read infinite. Then turn on ignition switch should read low ohms.

The charger finds it hard to charge the battery while the alarm is connected up. With the alarm disconnected but everything else connected it charges fine.

Haven't ever left the battery out the bike not on charge, so don't know if it self discharges. Would be worth checking I guess.

Do you mean do all the resistance tests you just mentioned with the battery out, or put the battery back in for the one where I turn the ignition switch on?

Leave battery out of the bike, connect one multimeter lead to the +ve battery lead and the other to chassis. With ignition switch in off position resistance reading should be infinite. Make the same resistance reading again but with ignition switch on the on position and you should get a resistance reading of some ohms.

Done that, got infinite from positive lead to frame ignition off.

Got 19.1 ohms from positive lead to frame ignition ON.

What I would expect for a satisfactory result. Infinite resistance says there is no leakage current when ignition off, just as indicated when you measured zero current. 19 ohms is not a true indication of the switch on resistance but confirms a change in resistance.

In an earlier post you said that you noticed the battery was flat when you went to move the bike, how long had it been before that moment since you last tried to start the bike or the battery had been charged.

About a week I believe.

EDIT: I did the last load of tests i.e the battery load tests and the positive lead to frame ignition on and off resistance while the alarm was disconnected, as I hate connecting and disconnecting that thing.

More history questions:

1. bike came with a battery that was suspect because it would not hold a charge so you kept in charged up,
2. could you start the bike with this battery without having to charge it up first.
3. you bought a new battery before you had the alarm fitted but did not use it, just kept it charged until after the alarm was fitted.
4. after the alarm was fitted you still get a flat battery when leaving the bike for how many days?

1. yes
2. I was able to start the bike for about a week after buying it, but I suspect the dealer had it on charge right up to when I went to buy it etc, after a week the battery needed charging about every week before it'd even turn over the engine.
3. yes
4. about 5-7 days

Just to confirm that your multimeter is reading current correctly, place the charged battery in your bike. Leave the -ve battery lead disconnected from the chassis and connect the +ve lead and -ve leads to the battery. Set you multimeter to 10A and put probes in the COM and 10A sockets. Connect the +ve multimeter lead to chassis and the -ve multimeter lead to the end of the -ve battery lead. With ignition switch in the off position there should be zero current as before. Now turn on the ignition switch, your neutral and oil pressure lights should illuminate and the multimeter should have a reading.

Right done that, first test I did was with the alarm still disconnected.

Reading when Ignition OFF = 0

Reading when Ignition ON =0.32

Then I plugged the alarm back in and tested the same again.

Reading when Ignition OFF = 0.01

Reading when Ignition ON = 5.32

EDIT: Here's a picture of the alarm wiring diagram, I managed to find the installers manual.