You'd have to elaborate in exactly where fuel is coming out. That'll be your problem for sure. Can only imagine a float has got stuck shut? More usually they would fail open though.

Typically if it runs only a short while it's often due to the vent getting blocked. Try again with the fuel cap open.

Edit: would fuel come out the vent if the filter screen in the carb were blocked?

Glad you like it better

Maybe brakes need another bleed since changing the hose, or maybe fluid got on disc/pads while you were bleeding it through? The single disc is OK, in fact it's very similar to a cbr500, but there's plenty of better stuff out there now.

Try the Facebook cb-1 cb400f group, most the traffic lives there now. That's the kind of part you usually get stuck with when breaking a bike. Someone will have one.

You've got me doubting myself now!

But no, writing up. This is general engineering convention, so you can identify a bearing or seal part number for replacement before you remove it.

Try here
https://www.facebook.com/groups/1119747858086718/

Don't cheap out mate. Oil seals, fresh oil, dust seals, bushes. You need the whole lot, at least on the bad fork.

The oil seal has the spring facing down. If you're not sure, put it in the same way round as it came out!

The knob you have looks to be correct. I don't remember the little screw being left hand thread, but since you're holding it you'd know.

Here's a very old pic I did back when photobucket was cool, explaining how to kill the cb-1 speed restriction.

http://i74.photobucket.com/albums/i264/a_morti/innards.jpg

It looks like the silver metal thread you have, should have a brass adapter to fit the plastic knob.

I imagine the top bush has deformed to the point it's sticking in the seal washer, or maybe the bottom one so that it's catching on the lip. They'll definitely want changing.

Start with the obvious question, have you removed the circlip which retains the fork seal?

After that, given the state of the tube, I would imagine the seal has rusted internally and swollen to a tight fit in the lower leg.

More force is called for. Heating can also help release the corrosion bind. This will, if it hasn't already, scrap the bushes.

The leak will be due to rust in the travel area rather than those huge scabs. I'd doubt there's enough material to grind that big scab back to spec, so it's probably scrap now.

There are loads of Honda's with shows 41mm forks. Mostly they'll be compatible but there are all different length, mostly shorter to suit straight bars or clip ons under the yoke.

Remove spark plugs, gap, clean with brass brush and solvent. Cut back 1/4" off spark plug wires.

These bikes don't start well on worn plugs. Replacing everything is expensive, the above often works at least enough to prove the theory.

I'm just running on the theory that fuel in the bowl is seeping past a crushed float bowl seal.

If it were the needles, I'm pretty sure it'd run bad. Otherwise why bother setting float heights at all?

Bike's running fine so doubt it's floats. To be sure, check if the oil level is higher than expected.

Seals can be ok but then fail if disturbed, which op said the carbs were cleaned. That's all it want, new seals.

If it runs fine then the needles probably aren't stuck.

New seals may solve it
https://litetek.co/Carb_Kit_Honda_CB1_NC27.html

Btw, that's a very random engine and frame combo. Any idea why it was selected?