Hey guys, I'm a member of this forum. So I was filling up at a gas station with a buddy of mine last night. I was told that its always a good idea to put premium 91 when filling up my bike. But then we had an epiphany, how much premium am I actually getting? Chances are the previous person who filled up used regular 87. When I looked at the hose I noticed its pretty thick, and theres a good 10 feet of hose, and who knows where the location of the pump is. My question is how much of the premium gas do you actually get in the tank? This isn't an issue if your filling up a car, but when filling up a small tank on a bike it is. I think this is a legit question, especially because of the the ridiculous prices here in Cali (almost 4 dollars). thanks for any input you guys may have

 

As you are posting in the F4i forum, I will assume you have an F4i, and I think I can shine a little light on the subject for you...

When I got my bike I had just gotten off a 1000RR which required premium fuel, and everybody I knew, had a bike that required premium fuel, so I just put premium fuel in my F4i assuming every motorcycle made required it. I did this for about a month until I read that part of the manual and saw that it stated use 86 octane or better. From that day forward I only put 87 octane in my bike, here is what I noticed.

My butt-dyno told me the bike was snappier, and, after the first few "test tanks" where I played with the redline all day long, I settled back into my regular riding style and I noticed my fuel economy went up a couple mpg on average. I was all like "WTF MATE?!?!!"

If you read up on what Octane ratings mean, you find that all an Octane rating tells you is that particular fuels resistance to detonation. So basically as long as you dont hear a knocking (premature detonation of fuel) then your fuel is a high enough octane rating for your particular engine. Higher octane fuel does not mean you get more power from the engine, however with higher octane fuel and a tune, yes, you can get more power from the engine. Think of it this way, your bike was designed to burn a fuel that is mixed with air and put under a certain pressure at a certain frequency in a temperature range. if you increase the amount of air, compression, or timing in the equation, you may need a higher octane due to increased pressure and temperature, but until you increase the air, compression, or timing 87 octane will do the job. 91 octane or better will still do the job, it will just cost you more.

I don't know why my bike felt snapier, or why my bike got slightly better fuel economy, maybe its because I was saving 25 cents a gallon by using 87 instead of 91 or better. I do know however, that I will not run a higher octane than i am required.

Hope that helps.

 

I think SPR misread the OP. He is asking how much premium gas actually comes out of the nosel at the gas station. It is not one of those threads debating which octane to use.

To answer the OP, I have no idea how much residual gas would remain in the line but I believe the gas stations would regulate that because they don't want people getting a little bit of premium when they paid for regular.

 

But would that really make any difference, since the previous customer got a little bit of regular when they paid for premium?

 

From The Wall Street Journal:

Q: I ride 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?
-- Paul Kowacki,
Orange Mass.
Associated Press


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.

 

Wow Gint! That has absolutely blown my mind! haha I never really thought about it, but am shocked to hear this. Good information. Thanks for that.

 

fill from stations with 3 different spigots for each grade. Problem solved

 

I was thinking about that too, but the problem is that's an old style of gas station, and they aren't being built like that anymore. So around me they basically don't exist. Still it's a valid point, for those of you that can, do it that way.

 

This. Frankly it's not going to matter unless you tuned for a certain octane.

 

The pumps not giving you a full load of 91 octane is actually doing your bike a favor so stop complaining. Stop using premium octane!!!!!