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Fuel

11329 Views 81 Replies 40 Participants Last post by  mkosirog, 
S
Fuel: I just got back from a 1,000 mile run yesterday and "putted" around a hundred today picking up a few things... Spending a little time on the "open road" revealed something interesting which I am attributing to different fuels.
First off I run nothing but 87 Octane since that is what the bike runs best with. When I am "home" I usually fuel with Chevron or Union 76... both good fuels.
I am "fairly" particular about my engine and the state of tune that it is in... I tune it for the way I ride and it runs pretty good... besides running fairly "healthy" I can also hear what it "doing" through the open Rineharts with no problem.. I listen all the time.

I had one run of about 40 miles where the speed limit was 55 and I was doing around 55 to 60 all the time on that stretch (real speed, not indicated). I was noticing a sound that I didn't like at that speed and it was coming from the combustion chamber.. sounded like poor detonation.. I checked it out on a return stretch and noticed the same thing... touched up the A/F mix a bit thinking maybe I was "a little fat" because I run a tad on the fat side.. not "real fat", but just enough to dust off "things" when passing.

Well this minor adjustment affected my performance more than I was willing to accept and the "sound" of poor detonation had not been helped any.. I retuned and set the bike up for "good running again", and the sound was still there... Next day I headed back to the same route and could still hear the "sound".. performance was "OK", not up to it's "usual", but "OK" -- I fueled with Mobil in the town and made the next leg of the trip to 29 Palms (from Parker Az.).. lots of open/desolate road... I was cruising around 75/80 most of the run.. took it to 55/60 for some of it and couldn't hear the noise.. bike was running "pretty good".

Fueled in 29 Palms with Beacon Fuel and headed towards Morango and Hwy 10.. noticed a "little" of the sound at 55/60 about 60 miles out of 29 Palms, but it was diminished... bike running "OK", not too bad. Ran it on the freeway into the San Fernando valley and fueled with 4 gallons at a Shell station and continued another 35 miles to "home".
TODAY I made a few trips on the freeway (about 100 miles total) picking up a few things and noticed the engine is running "great" in all areas of performance and the "sound" is totally gone... the bike even sounds "healthier" at idle (probably that final "tweek" I did to the A/F mix the other day), but the bike is definitely very healthy running on the highway and accelerates for passing with a very authorative "jump".

The fuel I was using when I noticed engine changes I had fueled with twice at the same station... good fuel, but of unknown ethenol mix.. that is what I am attributing the changes too.. I know the station.. they sell a lot of fuel and it and the tanks are clean.. it had to be the "mix" because the fuel itself was "fresh"...

For those that have been chasing the "tune cycle" and attempting to fine tune and having mixed results or results "less than your buddies", CHECK YOUR FUEL -- Fuel is a big deal if you are a "nit picker"... it was my Rineharts that first alerted me to this because I KNOW that everything is "on" engine wise, but there was some "sound" in there that I couldn't get ride of totally with tuning and when finally getting some "quality" fuel into the bike the whole world changed.

I'll be making a 300 mile run tomorrow on "business" (still on vacation)... eat your hearts out... I should have plenty of miles by the end of the next couple of weeks...

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R
You've got too much time on your hands Scars. But you are right. It is hard to find a fuel that is consistantly of the same mix. The stations around here buy from so many different suppliers it is hard to know what you are getting unless you set up your own portable laboratory!
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dirtdobber
I was having problems keeping my mpg constant. I know that 87 oct. is what the X is designed for. My mpg was jumping from 38 mpg to 36 and a few times to 32 mpg. I went to the middle grade and I am constant at 42 mpg
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E
I run nothing but 93 octane, and I get a consistant 47mpg. Also, I know that it has been said over and over that the 1300 runs best on 87 octane, but after trying 87 I went right back to 93 because "I" could tell a difference in performance. Also, if you remove your seat, there's a sticker on the rear fender that says 91 RON MIN, I take that to mean 91 octane minimum, so I use nothing but 93. I Know the owner manual says 86 or higher, but we all know that things been wrong before, besides, over 4.8 gals of gas the difference between 87 & 93 about $1.00.
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S
Update: Made a 280 mile run today.. pumped in 89 Octane.. "combustion noise" was gone... bike ran great... mileage on 87 Octane had dropped to 40/41 sometime back (used to be 45/50) and today it was 45/47... I'm thinking the fuel manufacturers have screwed up the fuel... bike used to run so good on 87 Octane.. it's been over a year since I tested fuel... 89 is so good I am going to try some 91 Octane next time and see how it does... down with ethanol and tree huggers. :stirpot::nono:
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Big-X
Hummm, it's time for a fill up also, I may try a different grade and see if I can tell a difference.
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B
Scars said:
down with ethanol and tree huggers. :stirpot::nono:
Click to expand...
Smart tree huggers know that ethanol made from corn isn't all that great for the environment, anyways.

I've stuck with 89 octane since I bought the bike and haven't had any problems at all. I may go with a higher octane on the next fillup just to see how it changes performance.
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D
the barometric pressure effects the engine note too, eh? but really man you got it bad, see a doctor.
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Buda_jim
My uncle is a retired Vice President for Humble Oil (Exxon) and once confided in me that because there are only a few refineries producing gas for so many companies lots of different gas stations are actually pumping the same "brand" of gas. If you were to park across the street from a gas station for a month you might be very surprised to see the different corporate logos on the tanker trucks that drive in and fill the station's underground tanks. The biggest station names (like Exxon and Shell, for example) will not normally receive gas from a competitor company, but when you are buying gas from most stations you have no way of knowing what company name was on the tanker truck, and it might be from a different source next time. This information was confirmed for me a few years ago by another guy I know who owns a small, family run convenience store and gas station.

Buda_Jim
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P
The book says 86 or higher, nobody wins at the racetrack on regular. If you normally use low octane fuel, change 1st to hi-test in a machine that you use normally under load. Lawnmower (rider preferably) or weed whacker, will do nicely and you will quickly see and feel the difference the higher octane makes.

Your X will gain Mileage, Performance, and Power with the change. And I'm certain ya'll will discover there is no monetary advantage to using low octane fuel.

A simple test: Pour a pint of regular on the ground, then chunk a match at it. Then do the same with hi-test, then ponder the advantage at start-up, and accelleration with high octane.
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pmack said:
The book says 86 or higher, nobody wins at the racetrack on regular. If you normally use low octane fuel, change 1st to hi-test in a machine that you use normally under load. Lawnmower (rider preferably) or weed whacker, will do nicely and you will quickly see and feel the difference the higher octane makes.

Your X will gain Mileage, Performance, and Power with the change. And I'm certain ya'll will discover there is no monetary advantage to using low octane fuel.

A simple test: Pour a pint of regular on the ground, then chunk a match at it. Then do the same with hi-test, then ponder the advantage at start-up, and accelleration with high octane.
Click to expand...
I AGREE 100%!!!!!!:cheers:
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F
Unfortunately, that's wrong. The bike performs best with 87 octane. It was made for that. Putting in a higher octane will not only do nothing to affect performance and gas mileage, but it will decrease the engine's life, due to the higher combustion temperature that the engine wasn't manufactured to deal with.

However, tomorrow, just to prove my point, I'm going to fill up with 93 octane, and check the gas mileage.
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Funkmon said:
Unfortunately, that's wrong. The bike performs best with 87 octane. It was made for that. Putting in a higher octane will not only do nothing to affect performance and gas mileage, but it will decrease the engine's life, due to the higher combustion temperature that the engine wasn't manufactured to deal with.

However, tomorrow, just to prove my point, I'm going to fill up with 93 octane, and check the gas mileage.
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I hate to burst your bubble, but I've already done the 87 vs 93 octane test and I noticed a big difference in engine smoothness and performance. As for the bike being made to perform the best with 87 octane, you can believe that if you want to, but if you remove your seat their's a sticker on the fender that gives a few specs, spark plug gap etc..., and it also states 91 RON MIN. I know the book says 86 or higher, but the book has been wrong before. I have always run 93 octane in all my vehicles and they have all performed well, but to each their own I guess.
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Funkmon, at 41 years old, and living in the "motor" city, you should know better!! Go ahead and make your "test", you'll be pleased with what you discover, especially in your northern climate. Me and Ewing invite everyone to try, and learn from their practical experience, and take the "1'st" story you hear about "anything" with a grain of salt.
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BG-Pete
Needless to say, I go by the book and run 87 in mine. That's what Honda recommends and that's what the dealer recommends. There has to be a reason.

But the one thing I have noticed is fuel color. I have been filling up at Mobil and never thought anything of the fuel...it looked like gas...slight amber color. As I was running on fumes the other day, I pulled into a BP. Still used 87 octane, but the gas was as clear as water. After finishing this off, I noticed that my mpg increased by almost 10%...same driving I always do.

After doing a little research, the amber color can be caused by 2 things, old gas or "dirty" gas. Since this Mobil is considered a high volume dealer (at least according to local news), I have to assume they are buying "cheap" dirty fuel and selling it at a slightly higher markup. Needless to say, I don't stop there any more for ANY fuel.

But check the coloration, see if you notice a difference.
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Shutterbug
Since it's just a few pennies more, I'll try the 89 octane stuff too.
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P
Gasoline often leaves the refinery in only 2 grades, that's low, and high octane. The local bulk distributor blends the mid-grade (grades), then delivers to the retail pumps (stations). Regular and Hi-test are the fuels we purchase direct formula from the refinery, the octane rating on the mid-grades could be anywhere in between.

Therefore only a measurement of performance between regular and Hi-test,
will be the only comparison that might remain consistant. Be sure and get the "good stuff".
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Charlie D
I run 87 and it runs ok, with the higher grades I seem to run smoother

on my 1300s on the back fender under the seat there is a sticker, says 91min, it also shows all the specs you need to know
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ibified
P-MACK Said: "A simple test: Pour a pint of regular on the ground, then chunk a match at it. Then do the same with hi-test, then ponder the advantage at start-up, and accelleration with high octane."

P-Mack: you DO know that 93 octane fuel is LESS combustable than 87, right? Just checking. The reason a high compression engine will knock less with higher octane fuel is that, since it's less combustable, it doesn't pre-ignite. preignition is what causes the "knocking" noise.

As for octane ratings:

RON: Research Octane Number
MON: Motor Octane Number

What goes into your tank, if you read whats on the label at the pump, is actually neither of these. Fuel from pumps (at least in the US) uses the (R+M)/2 formula, which means that they take an average of the two. Typically, your RON is about 8-10 points higher than your MON is. What this means is that fuel with a RON of 91 is actually going to be equivalent to somewhere between 86 and 87 {(R+M)/2, with R being 8-10 pts higher than M, is going to give a yield between 4 and 5 points down from R} I would guess that the RON posted on the body is for people in Europe and Austrailia, since that's where RON is the "headline" number listed on fuel there.

Octane itself is simply a rating of a fuel's resistance to autoignition. if you want a further explanation of it, read on:

Octane is measured as a relative mixture of isooctane (which is 2,2,4 trimethylpentane, an isomer of octane) and n-heptane. a fuel rated at 93 octane, for example, has a 93% mixture of isooctane to 7% n-heptane. The proportions of that mixture may not be precise, but the resistance to autoignition will be the same as if those were the exact proportions.

I can't give a definitive answer of what runs better, and nobody else can either. At least not for everyone. Ideal octane for a motor is going to vary based on atmospheric pressure, temperature, relative humidity, compression ratio, timing, and numerous other things. The best thing to do is to try each for yourself, check your mileage, and listen to what your butt is telling you. As for fuel mileage, additives are going to play a FAR greater role in fuel mileage than will the octane rating.

If you don't want to take my word for it, that's fine. After all, what do I know? I'm just an automotive engineer...
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ibified said:
I can't give a definitive answer of what runs better, and nobody else can either. At least not for everyone. Ideal octane for a motor is going to vary based on atmospheric pressure, temperature, relative humidity, compression ratio, timing, and numerous other things. The best thing to do is to try each for yourself, check your mileage, and listen to what your butt is telling you.
Click to expand...
Yep - I may switch off between 87 and 89 depending on the seasonal blends....(seems to run better on 89 Fall and Spring)......but I think "ya'll" who are touting 93 as some sort of "performance mod" - pure foolishness.
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