What is a typical dead volume on a gas pump fuel line?

[Twisties]

I tried Google and didn't get an answer.  Just curious because moto tanks are small, and the effect of getting some of another grade when a single hose is handling multiple grades s possibly larger than for a car.  My guess is that the volume of the line past the point at which the grade is selected is fairly small, under half a gallon.  But that is just a guess.  Anyone know?  

 

Seems like the best mitigation strategies are to

 

• Run the tank down as much as possible to get the largest fill you can.... but that is not always possible when riding in remote country.
• When riding with others that use the same grade, use the same line sequentially, and switch off who fills first.
• Where possible, use stations that have dedicated lines for each grade.

[Rob Nowell]

18 minutes ago, Twisties said:

I tried Google and didn't get an answer.  Just curious because moto tanks are small, and the effect of getting some of another grade when a single hose is handling multiple grades s possibly larger than for a car.  My guess is that the volume of the line past the point at which the grade is selected is fairly small, under half a gallon.  But that is just a guess.  Anyone know?  

 

Seems like the best mitigation strategies are to

 

• Run the tank down as much as possible to get the largest fill you can.... but that is not always possible when riding in remote country.
• When riding with others that use the same grade, use the same line sequentially, and switch off who fills first.
• Where possible, use stations that have dedicated lines for each grade.

Jan, you are one intricate sunofagun!

[lkraus]

Google common interior diameters for fuel hoses, pick the larger, 1".

Assume a length of about 25 feet (probably much too long, based on how I stretch to reach the far side of my car).

This hose volume calculator says the hose holds 1.02 gallons. A more likely length of 15 feet holds 0.6 gallons.

 

My '06 RT holds 7.1 gallons. A gallon of 87 octane mixed with 6.1 gallons of 93 octane will result in a tank of 92.2 octane. The short hose yields a tank of 92.5 octane.  I'll never notice the difference.

 

The LC R1200RT requires 89 octane and holds 6.6 gallons. Without a knock sensor the correct octane is a little more critical, but even the "long" hose scenario yields a tank of 88.7 octane, the short hose 88.8 octane.

 

The R1250 engine uses 87 octane so hose "leftovers" are not an issue.

 

There's a reason the various agencies that govern weights and measures allow single-hose pumps - the leftovers really do not matter.

 

 

[wbw6cos]

https://www.ksdk.com/article/news/verify/gas-pumps-fuel-customer-st-louis/63-44864c2c-725c-481c-a2ad-e0bd3579fa96#:~:text=The length of the gas,1%2F3 of a gallon.

 

Your mileage kilometers may vary.

[Twisties]

37 minutes ago, lkraus said:

I once researched common interior diameters for fuel hoses, assumed a length of about 25 feet (probably too long), calculated the volume.  If I refilled my tank at the point it went on reserve (~1gallon remaining) and the previous user bought 87 octane before II selected 93, I calculated that I'd end up with tank of about 92.5 octane, or something similar.  So, not enough difference to be concerned about.  

Looks like you are probably right.  I looked up some fuel lines and they were around 0.8" I.D.    Pi(r-squared)120"/61 = 0.98 l  That's area of the circle x 120" for cubic inches, divided by 61 to get liters.  About a liter.  Done worrying about this.

[Twisties]

2 minutes ago, wbw6cos said:

https://www.ksdk.com/article/news/verify/gas-pumps-fuel-customer-st-louis/63-44864c2c-725c-481c-a2ad-e0bd3579fa96#:~:text=The length of the gas,1%2F3 of a gallon.

 

Your mileage kilometers may vary.

Good reference.  About what I calculated above, guessing a 10' line.  Apparently it's not a real concern.

[Rougarou]

Methinks some of you all over analyze a lot of stuff,............a loooooooooot of stuff.

[Bernie]

I think mixing the fuel types at that percentage causes the top speed to drop by maybe 2.5 mph, but it is still within the required range to lose your drivers license and in some states to lose your bike. So don’t worry, you will be fine. 

[lkraus]

1 hour ago, Rougarou said:

Methinks some of you all over analyze a lot of stuff,............a loooooooooot of stuff.

I tried to get the word "oil" into my post, but decided that was just my mean streak at work.

[Rougarou]

20 minutes ago, lkraus said:

I tried to get the word "oil" into my post, but decided that was just my mean streak at work.

 

Ya, sometimes it's hard to fit Rotella into a Michelin thread.

[szurszewski]

8 hours ago, Rougarou said:

Methinks some of you all over analyze a lot of stuff,............a loooooooooot of stuff.

 

 

that's the trouble when you hang out with scienticians. or however you spell that... ;)

 

20 hours ago, Twisties said:

Good reference.  About what I calculated above, guessing a 10' line.  Apparently it's not a real concern.

 

Amusingly, I came to this very same conclusion by a slightly different process.

 

Non Impediti Ratione Cogitationis

[wbw6cos]

8 hours ago, Bernie said:

I think mixing the fuel types at that percentage causes the top speed to drop by maybe 2.5 mph, but it is still within the required range to lose your drivers license and in some states to lose your bike. So don’t worry, you will be fine. 

 

 

How does that affect your tire mileage?

[Rougarou]

1 hour ago, szurszewski said:

 

 

that's the trouble when you hang out with scienticians. or however you spell that... ;)

 

 

I gots some of those PhD clowns at my work, boooooook smawt,.....common sense, meh a few have that.

[Skywagon]

Roug…Well, what if you fill your tires with nitrogen like some shops do. Since its lighter than air, am I in danger of losing traction and floating away… or do I just get better mileage due to lighter overall bike 😁

[Twisties]

I thought this is the place.  You know, analyzing haircuts and of course, oil threads....  :-)

 

[Rougarou]

44 minutes ago, Skywagon said:

Roug…Well, what if you fill your tires with nitrogen like some shops do. Since in’s lighter than air, am I in danger of losing traction and floating away… or do I just get better mileage due to lighter overall bike 😁

 

Is that Rotella nitrogen or Michelin nitrogen,.....makes a biiiiiiiig difference,,......don't let me get Dunlop or Motul involve with that, and Castrol is outta the question because Shinko is much smoother than Mobile 1.

[chrisolson]

12 hours ago, Rougarou said:

Methinks some of you all over analyze a lot of stuff,............a loooooooooot of stuff.

 

 

With apologies to our departed Glenno

[szurszewski]

3 hours ago, Skywagon said:

Roug…Well, what if you fill your tires with nitrogen like some shops do. Since its lighter than air, am I in danger of losing traction and floating away… or do I just get better mileage due to lighter overall bike 😁

you know there’s a whole analysis of using nitrogen somewhere on this site, right? I mean, seriously…now I have to go look for it.