650 oil light

So... I have posted a few topics lately as I am desperately trying to get a 1978 kz650 running which has sat for about 5 years. I finally have gotten it to crank up and it needs some minor tuning but the oil light stays on continuously when running (I have only let it run for about 15 seconds) which concerns me none the less. The manual doesnt really say say a whole lot from what I have seen except for the electrical diagram to the Oil Pressure Switch (located in the oil pan?).
I have drained the oil and added approx. 3.7 quarts but the oil window is either clogged or something. I think the oil pump works because when the filter was off I would kick start it slowly and some oil would trickle out. Wondering why it is on and if I should be worried.
Which also kind of leads me to another question:
The oil window on this bike is like my other bike... small circle window with some metal behind it and a gap running between the metal. However on my other bike (same year) the gap runs horizontal and worked... this bike the gap runs vertically and no oil will show. Wondering why it is vertical? Why no oil will show in her?
Thanks for any replies for all will be appreciated

Vertical is the way it should go and the oil must be seen when the bike is on the center stand, engine at rest.

kzcsi

The window on my 650 is so dark I can't see the oil either, I'm going to clean it during my winter fix up. The oil pressure switch is behind the points plate on the right side of the engine. My light goes out when it is cranking. Take the points plate off, check that the wire is connected correctly and not shorting out on the switch or in the cavity somewhere, especially check where it goes through the grommet. If the wire is grounded any where along it's length up to the bulb the light will stay on, if it stays on when you take the wire off the switch it is a grounding problem.
Also,, remove the switch and crank the engine a bit, oil should come out of the hole this could get messy. Check that the hole in the bottom of the switch isn't clogged with sludge, it's happened before.
If oil comes out when cranking, there is no shorts to ground in the wire and the hole is clean replace the switch.

Awesome! I saw exactly where the switch is located....
However my itch furthers to get this bike running and yet leads me to another question.... (hopefully you guys haven't gotten too frustrated with me just yet).
Upon further check up on the oil window I see that it is clogged about 3/4 of the window but the unclogged 1/4 is at the bottom. The clog is a murky brown color which almost looks like mud. As I said the bike sat for a long time and I changed the oil 3 times already... and it was the same color as the clog 2 times....
The oil looks pretty good these days but if there is a clog there.... where else? Wondering if I should start the bike and let her run once I find out there is sufficient oil pressure.. and then change oil... or will this be dangerous? Should I run some additive through and try and clean out whatever it is....
Dont really know where to start on this one...

That muddy clog is probably from water collecting in the engine, oil and water mixed looks like mud. Do the oil switch test and get the light working so you know you have pressure. Then start it up and let it warm up good, then drain the oil again and see how it looks. It's a good idea to have a fan running by the engine so it gets some cooling air.
Ride safe

I would not put any additives in the oil, (1) it could affect the clutch plates causding them to slip or worse (2) if the additive breaks it loose there is a good chance of it plugging up the oil pump, and then it will get way ugly.
If you think there is a lot of sludge in the pan, pull it off and clean everything, a new gasket is cheap and a few hours of time will save you a lot in the long run

I agree with you BSKZ but I think some SeaFoam in the oil and warmed up would help clean things up? Then remove pan for cleaning.