83 kz440 problem starting

I am rather new to biking and know relativly nothing about them however i have worked on cars for a while so i am a little experienced with machines. Anyway on to the topic. I just bought a 1983 kawasaki kz440 ltd. It has been running great except for today i went to school and parked it, took a test for 2 hours and when i came back out it wouldn't start. i looked into the other posts about starting, but couldn't find anything similar. Heres what i know. I put the key in and turn it, everything comes on, headlights nuetral light etc... but when i push the start button nothing happens. no clicking nothing. the lights dont dim and its not the battery. i tried shifting into different gears and holding the clutch to start but nothing worked. so i walked across campus and took another final and came back 2 hours later. again no luck at first so i called my girlfriend to come pick me up. while she was comming i kept hitting the start button. i lifted up the seat and checked the wiring down there. i jiggled all the battery wires and the wires comming from the right handle bars but nothing worked. by that time she pulled up and i guess absently minded i still had my hand on the start buttom because when i looked up when she came over it started..... i didnt touch anything different it just went. so i drove to work and turned it off. worked for 4 hours and went out. it started right up. ive driven it for a few days since then and it hasn't done it since. this has never really happened before i can only think of one time and thats when i first got it i killed it trying to go in first gear. i had the owner come out and he flicked the kill switch into off and then back to run and it worked just fine however i tried that and that also didn't work and i also tried messing around with that switch too but it also accomplished nothing. sorry for the long post im just trying to get all the details in so i dont waste time.

Interesting.

If the starter was dying, I would think that when you hit the button, lights would dim, but like you said, they don't.

I wonder if there's a bad ground to/around the starter solenoid. If you have lights, you still have *some* grounds (there are many), but you might want to re-check those things.

I have heard of starters failing dues to heat, but I don't know what symptom they exhibit.

In your memory, was there any correlation to how warm the bike was when the problem occurred?

del

Thanks for all your help. I also was thinking it could be heat related as it was sitting outside on a fairly warm day but the ground idea sounds more promising. Ill try it out this weekend. Also to get to the starter i believe i have to take off the side case where the wire goes in. When i do that is it in with the oil? i guess im asking should i drain the oil out first so i dont have a big mess.
thanks again.