Had a discussion with a guy about gas from the pump. He said when you buy gas at a pump that has 3 different grades but only 1 dispensing hose, your first 1 to 1 and ½ gallons is actually whatever grade the person bought who last used the pump. His reasoning is the grade of gas the last person bought remains in the pump plumbing and the hose after the pump is shut off. I always fill up near home with 93 octane ethanol free gas. But usually my bike will only take 2 to 3 gallons. If what he said is true, half of the gas I put in my bike could be 87 octane 10% ethanol formulated gas. He said the only way to prevent this is to find a pump that has a separate hose for each fuel grade. What do you think?

 

More like 1 to 1 1/2 CUPS.............not enough to make a difference.

 

I believe that it was cHarley who posted on this subject many months ago and stated that the amount in the hose is very minimal. My bike at 10.5 to 1 compression ratio is very susceptible to gas quality but has never run any different on the single hose gas.

 

Anywhere from 1 cup to 1.5 pints depending on pump design and hose length.
You have a 4.5 gal tank, filling up early when you only need 2-3 gallons only increases the low octane ratio.
Assuming you fill with 4 gallons of 93 and the hose has ~1 pint of 87 octane left in it, the effective octane in your tank will be about 92.75.

 

I buy all my gas at Chevron and they have a dedicated 94 octane nozzle and line.

 

I prefer to fill up at 3-hose pumps, but a few years ago I did a calculation on the capacity of a typical gas pump hose (and associated interior piping to the pump) and it wasn't a lot of gas...maybe 1/8 gallon or so. Still, my Ironhead tank only holds 2 gallons, so I'd rather have straight 93 octane in it.

 

What Mich said.

 

Yeah, unless forced differently (tank capacity clue), I always try to go where they have dedicated line for premium gas (91 octane around here), and use Chevron preferably.

 

When I was a kid, before self serve stations, I knew a guy that let me go around and lifting the hoses to fill up my bike just before he closed for the day.

 

Slightly off topic but I'm pretty sure my dealer told me to use 87 octane..... Is it better to use 93?