Putting "Premium" in your bike

Don't want to get into "You're too lean if you're pinging in 87 octane", etc.
Assuming you need to run premium in your bike...
If you have a two or three gallon tank, and you select 91 octane at the pump, how much 91 do you actually get once whatever is left over from the last dude's 87 octane fillup, which is left in the hose, gets pushed into your tank? A gallon?

Fuck knows, but you're probably getting a litre or 2. . I wouldn't own a bike that required premium

Just let the first 1/2 gal. go on the ground, then fill up. Don't screw around, you want straight 91 or not?

^this^

I just pump a quart or two out on the ground.

The capacity of a 100-foot length of 1-inch diameter hose is 4 gallons.
How much line is between the nozzle and the pump's switching valve?

I love old school thinking!


That piston needs a headstone,
Here lies a 91 octane
fed 87 in the hose

I will do my best to remain silent now,
and let the men with white collars,
finish the sermon.

Just an academic query. I don't need or run anything but 87. But as I was filling up last time, I began to wonder just how much of one's requested grade one is actually receiving, given the hose capacity. I figured some erudite FFs here could enlighten me. I was hoping there wouldn't be digression into ad hominem digs at the "necessity" of running premium. I was merely questioning the return on investment when figuring the typical (non adv-dromedary) bike fill up quantity. I don't know how deeply buried in the physical pump lies the switchgear. I would hope for the consumer's sake that it's as close to the nozzle as is practically possible, but I don't imagine that's the case. I was just hoping someone here would know these things.

You ride a KLR? Gotta be------. :huh BTW, if you gear it down to where it's slightly usefull on hard dirt, it helps when you're trolling along on the street checking out the gutters for spare change.

We were just hanging out in the shade at the gas pumps watching you gas up,
when we heard the ding ding in your head.
No one was knocking you like low octane.

Wtf?

I don't ride a klr, and I don't care what you ride. I was asking a question about the mechanical qualities of a gas pump.
Nevermind, I guess.
Ad hominem seems to be the rule, not the exception nowadays....

G money, what's the story on that piston! Was it yours?

No, it wasn't his and it wasn't mine either. I simply found the pic on the 'net. That can happen with prolonged detonation caused by, among other thinks, using gas with too low an octane rating.

We were just having a bit of fun here. You should join us down in the Jo Momma section. It's like a bar where we can have a nice chat while looking at some nice girls.

Well, maybe it's not too late to get this dumb thread of mine sent down to the basement! How do I do it? Post some boobies or tell a scatological joke?
Please advise.

The three grades of gas are all plumbed to the individual pumps. The amount of gas left in a line is all you need to worry about. It has been figuered out before, and the amount is pretty small. Not worth getting all worried about.

http://online.wsj.com/article/SB122944043385810527.html

Even at 1/3 of a gallon you are not going to significantly effect the octane level if you are adding 3 gallong. The 5 points in octane difference doesn't lower the total by a significant amount. For instance, if you have 3 gallons in your tank, that is nine 1/3 gallons. Octane at 87+91+91+91+91+91+91+91+91=815/9=90.55555556 Octane. You lose less than half a single octane level. If your tank is bigger than three gallons, even less. For instance, a GS at 5 gallons is 90.733333.

Jim

I have high performance motors that encourage 93 in both cars and bikes. They all run fine on 87, but don't get as good fuel economy.

Unless you drive them hard it should work the other way around. The higher octane gas just prevents pinging in high performance motors.

http://mn.gov/commerce/weights-and-measures/images/OctaneFacts.pdf

Jim

Definitely the boobies. Would sure help my piston. Go for it!

Not true. Stations usually only have 2 grades of fuel in the ground. Fuel is pumped from both in ground tanks and mixed to the proper octane in the pump and then dispensed thru the hose.

http://ethanolpumps.org/how-they-work.html