Help with my 81 kz440!!!

So here's the problem, I'm 3/4ths of the way done with my first cafe build and I started it today and it runs for about a minute then just shuts off. It wouldn't start after so I waited a couple hours while working on the seat. Then later I took it out of the garage and it fired right up. So after a couple minutes I take it around the block. And it was going good at first (besides a couple big RPM jumps) and then halfway down the block it started loosing power and eventually died. So on the way back (only half a block) it decides to start. So I hop on and I'm BARELY getting any power out of it. With the throttle pulled way back it's barely crawling. Then it dies again and just won't start. Any ideas? I'm running 20w-50 and the back light and turn signals where off if that matters.

Sounds like it runs out of fuel. Make sure the fuel line is not pinched and that the petcock strainer inside the tank is clean. Oh, and make sure you have fuel in the tank. Believe it or not some folks have worried about why their bike wouldn't start or run only to eventually find out it was out of fuel. Ed

Thank you that's a very basic thing that slipped my mind (not the having gas but the kink in the line) I'll look into that solution tomorrow and see what comes from it

Still no luck. Also does anyone know where the mixture screw is located?

The idle mixture screws are sealed off.
They are set at the factory.

well that sucks. ill have to look into another adjustment method. do you think itd be worth re jetting?

The symptoms you describe are typical of gas cap not allowing air to escape. Try starting it with the gas cap off and see if it still dies after a few minutes. If it still dies then it is something else. If it doesn't then you've found your problem.

As soon as the battery's done charging I'll try this. Wouldn't that be something if it was as simple as that

My 2 tips have already been posted by 650ed and diggerdanh. Make sure you have fuel and the tank can breath.
Good luck

P.S.
You can drill out the mixture screw caps if you need to but unless youve stripped the carbs for sonic cleaning or something like that they should be ok as they are.

Talking of which,would the difference between 'sonic cleaning' and 'ultrasonic cleaning' be the size of the hedgehog?

Okay so now it won't start at all. I took out the plugs and the right one was wet and fouled and wouldn't spark. So I changed it out with the old one and now it'll spark. And it looks like the right spark plug is putting out a bigger one than the left. It's fat and blue, and while the left one is strong and consistent it's a dull yellow. I can smell the gas on the plugs but now it just won't fire

I had this prob on another bike of mine and it ended up being the coil firing on one side then breaking down completely. I would let it sit for 10mins it would fire back up with weak power then shut down again. I put new coil and wires on and haven't had the prob since.

Awesome! Any idea where and how much one for my bike is?