Can I ride 80km on a bike with no pump and other tooks?

You know Murphy's law? "What ever can go wrong, will go wrong"?

You can ride for a year doing 40 km per day and not need any tools or pump. Then you leave them at home, since you never need them anyways, and get a flat at most inconvenient and out-of-the-way place of your next trip.

You can risk it if you want to, although you'll need to be prepared to walk home or phone for help if you get a puncture or something else goes wrong.

A pump and a basic repair kit (and ideally a first aid kit) won't take up much room.

Not a good idea. You can get a flat tire even after just half a mile no matter the type of road. They make pumps that you can attach to your bike. You can also get a small bag for under the seat to hold a patch kit and other small tools.

Other tooks? Who took what? Oh...other tools!

Several years ago I was roughly 15 miles from home with everything needed to patch a tube & replace a tube - both. Everything except a source of air. And the closest gas station was 2 to 3 miles away.

I haven't been on a bicycle since without EVERYTHING needed to fix a flat and / or replace a tube - including a good frame pump. Don't care if I'm riding 1 mile or 100 miles.

Why not carry everything to need to at least patch a flat, tire levers and have a spare tube. The frame bike pumps are cheap and can save you a lot of walking.

A flat wont help you if it is all down hill.

Sure you can... maybe. You have no idea what may happen over almost 50 miles of roadway. A small frame pump and tire repair kit don't cost much, and may be the difference between completing the ride and walking back. I have a tire repair kit in a very small under-seat bag, and a frame pump. I've not had to use the tire kit, but I have had to use the pump on the side of the road.

You'll also need a LOT of water with you. I have 2 frame mounted cages with water bottles, plus a 2 liter Camelback!

If you have a flat, you won't be riding those 80 km, your ride will be over at whatever mileage the flat occurs. How big a chance you are taking is impossible to tell. I haven't had a flat on the road for quite some time, but I still carry tools, tubes and a pump. Every passing kilometre brings me closer to my next flat

That's not a good idea.

My dad once flatted 3 times over a 50 mile ride. Yeah, you need to bring stuff with. Also important, food and water.

if you are lucky or don;t mind walking

You can; I've seen riders who do it all the time, but as others have noted you're taking a heckuva chance.  If you're going to have a support vehicle closely following you then they can carry all this stuff and you wouldn't need to.  But taking an 80k ride and being followed by a car all the way kind of defeats the purpose of the bike ride, right?

If you are lucky yes if not no.
It is a long walk with a flat tire.
Carry a pump a repair kit and the tools to fix a flat.