Really interesting conversation going on, I'd just like to add a little simple engineering "maths" on the question of empty tank versus full tank being sufficient to provide enough gravity pressure to feed the carbs.

The pressure in the tank when almost empty is pretty much atmospheric pressure. The fuel level in a nearly empty tank is say 30cm lower than when the tank is full. The density of petrol is approx 0.75 (cf fresh water 1.0). 1 bar = a 10.3m column of water = 13.7m (10.3/0.75) of petrol. So 30 cm of petrol generates an additional 0.3/13.7 = 0.022bar. So the pressure at the bottom of a virtually empty tank is 1 bar, and when the tank is full it's 1.022bar. I don't think a full tank will make any difference to the fuel flow compared with an empty tank. Sorry I can't help as much as the others with the mechanical/electrical diagnosis.

 

Scrambled eggs to me lol!

 

Gronk, - as an "egg-lover", I guess that must mean you like it (???). Haha.

 

I love eggs in any way shape or form no doubt. "Scrambled eggs" is an expression in my neck of the woods that means the subject matter is just skimming over the top of my scalp

 

That holds true for a river. A river is at atmospheric pressure at the surface where most of the flow is and millions of gallons of water flow. The next time you take a drink from a glass, think about your engine consuming that much liquid. Your engine will not be able to consume that much, even at atmospheric pressure.

 

I think Honda did this to make their bikes start easier. My old Suzuki is a pain to start, cause if it sits too long, there won't be enough fuel in the float bowls. I crank it a bit and if it won't fire, I then need to turn the petcock to 'Prime' which just bypasses the vacuum spring to let the fuel flow freely. I count a couple seconds, then turn it back to 'On' and crank the bike a few times til it starts. Honda wanted a reputation for reliability, and having a bike that starts right up on the first or second crank really makes a bike 'feel' reliable. Hence, one of the benefits of a fuel pump is that it 'self-primes', meaning Joe Consumer has one less thing to worry about, and while his buddies are kicking or cranking away, he's already at a comfortable idle

It also would have been useful when they started putting reserve tanks underneath the seat to increase range. Then you actually need a pump to overcome gravity

Looking back, it seems like every old Honda owner liked to brag about how easy it was to start the bike. Runs like a Honda, they said

I think it's an elaborate marketing ploy

 

Confirmed. Problem went away once I blew out the breather hose with compressed air. Put about 500 kms on it, and no more random stalling. The breather hose tees onto a coolant overflow line (really Honda??) and with the bad t-stat long ago in the bike's history, no surprise it had been clogged

I owe you one. Thanks

 

I don't think that was Honda. The breather is just that, a breather. I think some owner before you didn't have a clue and was hooking things up ***** nilly.
Glad to hear she is running well, happy ridding!