KZ750 electric starter problem

Hey guys I bought my 1977 KZ750 about two weeks ago. The previous owner had it sitting for a year and a half, battery that came with it barely held any charge. But when hooked up to the charger everything worked meaning lights, signals and electric starter. So i got the battery tested at a shop, battery ended up not even charging so I purchased new one. After I install it all lights work I kick start the bike ride around for half an hour. When i go to try to turn it on an hour after with the electric start everything shuts off and even the ignition lights are off (neutral light), and bike is no longer even starting with the kick start. Any idea what can be my issue?

Does/did the battery seem to be dead? If so, the you gotta look at the charging system, likely the rectifier. If the lights were good and bright, and pushing the starter button caused instant death to everything, I would look at the main fuse, and search for what caused it to blow.

The battery was running strong and fully charged when i first put it on, and while riding. Until I pressed the electric starter button then its like if the battery was not even there. I checked the main 20A fuse and its good I even replaced it with a spare and still no sign of electricity.

JavierF, a couple things to check,

1) Ignition switch has 3 positions, full left - off, 1st position to right (straight up)- on (ignition and lights), full right - park (ignition off, all lights except tail off). The key can be removed in this location and the rear tail light is on for side of the road emergency parking.

2) There is a shut-off switch on the throttle housing that must be on for power to the ignition.

3) there is a starter interlock switch in the clutch housing that requires the clutch lever be pulled to complete power to the starter button.

Good Luck,
Jim

Ok I went through all the checks and had no luck.
1) no light turns on in any position on the ignition switch
2)The shut off switch on the throttle housing was on
3) and the clutch was being lever was being depressed while trying to engage the starter

I dropped the motorcycle off at American Motorcycles in Paterson NJ they are going to run an electrical evaluation on it. The mech told me that the battery was completely drained and that it most likely had to deal with a problem in the charging system. Ill post up when I find out what the problem is. Thanks guys