Thought this was interesting?
I have noticed that sometimes after 
refuelling my 1999 Hayabusa doesn't run so good. Its been tweaked and runs a Power Commander so maybe its a bit more sensitive to the difference in octane? You're talking about one litre of fuel left in the hose, which I suppose could make a difference?
don't think its a big deal - more of a curiosity item?

I have a motorcycle with a typical three to four gallon gas tank. I ride where fuel stations are farther apart, so I fill up when the tank is still half full. The bike requires premium fuel, and doesn't run well on lower octanes. If the previous customer was pumping regular fuel, I assume the refueling hose is still full of regular fuel, perhaps a couple of gallons. This would mean I'm initially getting a mix instead of pure premium fuel. Is this a genuine concern, or does the system have a mechanism for evacuating the gas pump hose between uses?

A: It is a genuine concern, but one that motorcyclists tend to appreciate more than car drivers. According to the American Petroleum Institute the gas-pump hose typically retains about one third of a gallon of fuel. So when you pump a couple gallons of 93-octane premium after the previous customer pumped 87-octane regular, your fuel load would be diluted (not to mention overpriced).

This is more important to motorcyclists because bikes have smaller fuel tanks and a lower tolerance for low-octane gas compared with most cars. I have found that high-performance motorcycles designed to burn premium fuel run poorly on regular. They generally do not have the complex engine-control systems that allow cars to run on fuels of varying octane ratings.

I don't think diluting your premium fuel with a little regular will harm your motorcycle, especially if you always select the highest octane rating available.
However, next time you're filling up you may want to get in line behind the driver with the highest-performance car in the station.

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Not an issue in Australia. We don't select which fuel comes out of the one hose like foreign pumps do. There is a hose for every fuel type, so three or four hoses per pump.

According to a conversation I had many years ago when I was working in the fuel industry as to why it's like this, it's for this very reason! There are very strict laws about fuel delivery in Australia and if you're paying to 98RON premium fuel, all your fuel must be 98RON.
Live free or die!
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Thanks mate!
obvious when you think about it. 
I’ll rest easy now!
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In my early days of riding motorbikes (1960s) many servos had two stroke fuel as well. The pump had a selector for the oil/fuel ratio and I could fill my premix two stroke bike without having to guess at the amount of oil required for however much fuel was left in the tank. Those pumps also had the problem of different fuel left in the hose depending on the previous customer.

I lived in Yass in those days and I think we had two stroke available because of all the fishing on Burrinjuck Dam. The only two stroke pump I see these days is on the wharf at Brooklyn on the Hawkesbury where my brother on Dangar Island fills up his tinny.

On the other hand, I try to avoid pumps that include a diesel hose. That stuff seems to spill all over the place and it's too easy to slip when getting the bike up off the stand.
Cheers, Kim.

From Woodrising (no, nobody else has heard of it either)
Rides a Springfield Dark Horse
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