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Discussion Starter · #1 ·
Went from my worst tank to my best back to back.

Worst- 43.12 mpg. Cold snap (for Seattle=upper 20's for morning commute), all city, short trips, hills. Not good.

Next tank is best- 71.44 mpg :shock: Whidbey Island perimeter tour with buddy, temps in mid 50's, mostly level terrain, speeds typically between 35 to 45 with short blasts to 60.

I checked the math a few times ( I usually figure it out at fill-up) and even looked down the filler when the pump shut off the first time. No lie. Followed with a tiny top off.

How is that for rangy?

PS- Lifetime avg to date @ 2200 miles=51 mpg.
 

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i usually find i get much better mpg on the highway than in the city.

though not near as bad as yours in the city.

jason
 

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There are just too many variables ... I was city riding the other day and got 58 mpg ... I usually get low 50's on the highway and high 40's in the city. The difference I think was the area I was in had longer stretches between lights and I got almost all the green lights. Also, the cars in front of me limited my acceleration so I was forced to take it very easy on the throttle. I guess it kind of makes sense anyway.
 

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Discussion Starter · #4 ·
I've noticed that extended cruising above 5000rpm (around 60) drops the mileage down a little; it seems happiest in the 4000-5000 range, with 45-50 being the optimal zone. This tank seems to support that, but YMMV, I guess.
 

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I just returned from a weekend beach trip and discovered something that goes against what I had believed to be true about this bike. I used 87 octane fuel going to the beach and ran two tanks through the bike...mileage average about 53 mpg. Temperatures in the low 90's and of course I was riding with the prevailing winds going to the beach. Coming home, I used 89 octane and got an average of about 58. Again temperatures in the low 90's and this time I was AGAINST the prevailing winds but got better mileage by a good 10%. So, the lower octane fuel has more BTU/gallon than the higher octane fuel and I was going uphill and against the wind going home and I still got better mileage. The only reason I can think of for this to have happened that way is that the extra octane allowed the engine's computer to run a more aggressive ignition advance curve and help the mileage that way. That used to work in the old cars where you could set the timing. The only other explanation is I finished breaking in the engine going to the beach and that helped it do better going home....anyways, thought some of you might be interested in trying your own test with different grades of fuel to see what works best in your bike.

Cheers!
 

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I don't believe lower-octane gas contains more BTU/gallon--I was under the impression that all gasolines contain roughly the same amount of potential energy, except possibly gasohol where the ethanol concentration lowers the overall content since ethanol is less energy-dense. But with gasohol, the concentration of ethanol is usually 10% or less, so it's still not significant (although I noticed the slight ~2mpg difference when I drove out to the midwest a couple years ago; everything west of Pennsylvania was gasohol)

Getting higher fuel economy with higher octanes might mean that your engine was knocking under regular octane, even slightly, either way 87-octane probably wasn't the "ideal" rating for your engine.

What is the general recommended grade for the Majesty?

PS- A whole horde of information about gasoline is available at the Gasoline FAQ: http://www.faqs.org/faqs/autos/gasoline-faq/part1/

Of interest is Part 3, which begins with info on antiknock ratings and such:
http://www.faqs.org/faqs/autos/gasoline-faq/part3/
 

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Yeah. High performance (read high compression) engines require high octane. But running high octane in a regular engine does nothing but cost you more.
 

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Are you saying the Majesty has a high enough compression that the higher octane fuel should help, or are you saying it isnt high enough that it will make any difference??? Plus there was one other variable...all the fuel I bought coming back home had ethanol in it...and should therefore have given me worse mileage. The whole thing is confusing...the results dont agree with seems to be common knowledgee and verifiable physical characteristics of the fuel, the terrain, or the bike itself.
 

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It's entirely possible that the Majesty benefits from premium gas in your case. As every engine is different, it's hard to say whether the lower energy of ethanol was outpaced by the antiknock qualities, plus there's also the factor of measurement error--did you fill the tank to the exact same point in all instances? Also ethanol burns leaner since it carries a small amount of oxygen with it inside the molecule, maybe that factored in here somehow. I'm not up on how the Majesty's fuel management/emissions system works (got my shop manual coming in hopefully by the time I get the Maj :D)

My experience with gasohol in my car (2000 Nissan Maxima 5-speed) was that gasohol gave me slightly (well, on the "butt dyno") better performance, but slightly poorer fuel economy. The power felt like it began to drop off around the 2nd fillup on non-ethanol-enriched fuel back home, along with a return to higher fuel economy. But then a 3.0L V6 is different from a 0.4L single-cylinder, so it might be different.
What does the owner's manual for the Majesty recommend? (I don't have my Maj yet, should hopefully arrive this friday :D :D)
My Maxima has a label on the inside of the fuel door that says "PREMIUM FUEL RECOMMENDED FOR MAXIMUM PERFORMANCE" and I have verified this--87 or even 91 octane gas produces a measureable drop in fuel economy, usually no more than 1-3mpg but the subjective "butt-dyno" definitely detects the extra sluggishness during heavy acceleration...
 

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the owners manual states that you should use "unleaded fuel only with a research octane number of 91 or higher"

our standard ulp here in oz, is 92 RON, and the premiums
(there are two different levels, making a total of 3 different unleaded
fuels) are 98 RON , and the newest one we have here is 100 RON.

i have always gotten better mileage with using the 98 RON ULP.
have not used the 100 yet (as i don't think the majesty warrants its use)

jason
 

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In most countries (including all of Europe and Australia) the "headline" octane that is shown on the pump is the RON, but in the United States and some other countries the headline number is the average of the RON and the MON, so you get Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2. This means that the octane in the United States will be about 4 to 5 points lower than what is same fuel elsewhere. Same fuel different rating method. 87 octane fuel, the "regular" gasoline in the US and Canada, would be 91-95 (regular) in Europe. In the US at a BP station the octane ratings are Super unleaded (93 octane); Plus unleaded (89 octane); or Regular unleaded (87 octane) I'm using 87 octane with no problems so far
 

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When I was in the early stages of breaking in the engine, I ran the 87 octane regular we get around here with no trouble. No hint of pinging or knock at all...and that has continued to be the case. I put the higher octane in it just because I was riding at high speed and therefore running it harder than normal and the weather was hotter than normal. I figured the two conditions might warrant a little extra anti-knock for safety. If that is true, then that would certainly explain the moderate mileage improvement. I am sure the engine management system on the Maj has spark retard if the knock sensor detects any detonation, just like a car. Anyway, we'll be running the middle grade for a while and see if the mileage numbers continue to stay a little higher. If they do, then that will tell me what I need to know. My car is the same way, wont run on regular but likes the middle grade.

Cheers...hope everyone is staying cool...it was 97 here today at 5 o'clock
 

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My 2006 owners manual says:

"Your Yamaha engine has been designed to use regular unleaded gasoline with a pump octane number [(R+M)/2] of 86 or higher, or a research octane number of 91 or higher."
 

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I read the manual after I got the bike and ran regular unleaded in it and may eventually go back to it. In the meantime, this past weekend was my first long roadtrip, and it was hotter than usual and I was riding faster than I have for longer periods...I thought the changed conditions warranted a change in fuel. Maybe not...but then again. My subaru manual says 87 octane, but it rattles like castanets on anything less than 89 octane. The bike doesnt rattle or at least I cant hear it if it does...wind noise being a major offender. So whether it was designed for 87 or not isnt really the question...did this bike come with a slightly higher octane requirement??? We'll find out after a few tanks of the middle grade. If there isnt any change then I will go back to 87 and will just shut up about all this. :)

Cheers
 

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I've never run anything in mine, but good old, regular unleaded 87. I have found though that a very small difference in the ammount of fuel in the tank will make a big difference in a roughly 4 gal tank. I always fill mine up into the filler neck where I can see the level, and I consistently get 60-61 MPG. And I can usually get another couple of tenths at least after pump shut-off.

Figure if you're a .2 low on one tank, and then .2 high on the next tank, you've got a .4 gal swing. That's a big difference in figureing gas mileage.

Example. 90 miles / 1.5 gals gives you 60 mpg. But 90 miles/ by 1.3 yields 69 mpg. 90 miles / 1.7 gives you 53. So you see, a very small difference in a "fill up" will give you a big variation in your mpg figures.
 

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I usually run 87 or 89 ... just depends on how sunny it is :?:

Have not noticed any real difference, but it seems to be just a bit smoother with 89 ... could very well be my imagination, though.
 

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Hi Cajunbass,

you are absolutely right about the error...and also unless the bike is in the same position when you fill it each time you introduce additional errors. I try to be as consistent from tank to tank as is humanly possible. Over a period of time, even my human errors in filling consistently should average out and show me whether an octane change makes a noticeable difference or not. Over the course of 6-10 tanks of fuel, I should see a pattern develop that either supports or refutes the notion that my bike needs the additional octane for best performance/fuel economy. After that, I'll compare the overall average mileage with the tanks that came before on regular and we'll see what the numbers tell us. Hope you guys and ladies have a great weekend! We're off to go whitewater rafting today...whoohooo!!!
 

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The engine was built and designed for 87 octane. Higher octane fuel will not do anything for your fuel economy, The higher the octane rating, the slower it burns.
 

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hotshoetom said:
My subaru manual says 87 octane, but it rattles like castanets on anything less than 89 octane. The bike doesnt rattle or at least I cant hear it if it does...wind noise being a major offender. So whether it was designed for 87 or not isnt really the question...did this bike come with a slightly higher octane requirement??? We'll find out after a few tanks of the middle grade. If there isnt any change then I will go back to 87 and will just shut up about all this. :)

Cheers
Tom, you'll find your subaru has a significant amount of carbon build up in the cylenders. That increases the compression ratio and requires higher octane, slower burning fuel. I'd recommendcleaning the injectors if njected and or running a few cans of additive such as BG 44k. Either should do a fairly good job of removing the carbon. Water does a fantastic job as well, but is risky. Have to drop exhaust system, as it'll damage convertor and trickle through at high rpm to prevent hydro-locking engine and related massive internal damage! There's also a small possibility the knock sensor, map/barometric sensor are not functioning as intended too.
 

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For decarbonizing, there's a product you can buy at Advance Auto and probably Autozone called "SeaFoam" that does the job very nicely.
 
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