How long does it take fuel to move from tank to engine?

[mike42]

Hello All

I've got some old unleaded in my motorbike tank. I plan to siphon it out and then top up with fresh fuel. Once I start the engine and leave it to idle, how long would it take before the fresh fuel hits the cylinders?

I appreciate it its a "how long is a piece of string" but there must be some kind of rough idea. e.g. I was thinking of leaving it idle for 5 minutes would that likely be enough or should it be more like an hour or something? I can't ride it at the moment and I want to get the old fuel out before potentially selling it.

[Super Sonic]

Give it a slosh about to mix the fuel.

[Speed addicted]

Given it’s got to travel about a foot at most I’d fire it up, let it warm a bit and rev it a few times. I’d think it would ge seconds rather than minutes to get the fuel through.
If it’s an older bike with carbs let it warm enough to run without choke, or close the choke before switching off to avoid fouling the plugs.

[Pica-Pica]

Calculate volume between tank and engine work , consider mpg at certain speed and this revs, then miles per litre, then consider revs for that mplitre It's just maths.

[Richard-D]

The answer is very dependent on what type of fuel system your bike has. Is it a single outlet to a carburetor or fuel injection with a return to tank. If very modern it may even be returnless injection.

What is the bike?

[tumble dryer]

13.826 seconds.

Ignore all of the nonsense above.
(Don't)

[Stick Legs]

Why not pull of the fuel supply hose and let some run out?

[ssray]

Get as much old fuel as you can put of the tank, put some fresh in.
If it won't start then try easy start