Octane Rating

I have heard of several FJR owners mention that they use regular octane gas in their FJR. I wanted to see what the majority are using.

Interesting to find out more, so bump.

I use the foreign octane. Works great in my FJR.

Baaaaaaad toecutter! Just can't let a poor dead dog lie? Huh?

The book says to use regular, so that's what I use.

Since the octane rating of regular varies by region, perhaps the survey ought to be rewritten 'regular', 'mid-grade', 'premium' or 'super'.

bramfrank said:

The book says to use regular, so that's what I use.
Since the octane rating of regular varies by region, perhaps the survey ought to be rewritten 'regular', 'mid-grade', 'premium' or 'super'.

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Very good point, Since the higher elevations have a lower octane rating. Parts of northern Arizona and New Mexico offer 85 octane as regular

If it makes you feel good, use the most expensive petrol you can find and buy the $10 quart oil and eat at Morton's every night in your Armani suite etc etc. You can live successfully without all that and so can your bike. The manual says no need so I resist the temptation to treat my bike like I treat my dog who gets the very best no matter what!

I noticed a sticker on my bike the other day that specified "RON 91 Min." which I have come to learn is 87 in US values.

I'd like to hear from TWN, who claims a regular 45-50 mpg, on what flavor of Ca gas he's running. I get 36-40 with my riding habits and full up (with Skyway spacers) V-Stream on 87 octane. It does remarkably better with Nevada petrol.

I have a good friend who's always said, "The best is good enough for me."

Can't answer the poll accurately because I run two different octanes, depending on the season.

93 April-October, 89 November-March.

This is a hot and humid climate during summer and I err on the side of higher-than-necessary octane to avoid any chance of detonation/ping.

The winter mix of gasoline in this region truly sucks, with mileage suffering as much as 35% against the same brand/octane in summer.

I noticed a sticker on my bike the other day that specified "RON 91 Min." which I have come to learn is 87 in US values.

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Not my words but posted here for others.

The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel through a specific test engine with a variable compression ratio under controlled conditions, and comparing these results with those for mixtures of isooctane and n-heptane
In most countries (including all of Europe and Australia) the "headline" octane that would be 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, sometimes called the Anti-Knock Index (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2. Because of the 8 to 10 point difference noted above, this means that the octane in the United States will be about 4 to 5 points lower than the same fuel elsewhere: 87 octane fuel, the "regular" gasoline in the US and Canada, would be 91-95 (regular) in Europe.

Gasoline pumps typically post octane numbers as an average of two different values. Often you may see the octane rating quoted as (R+M)/2. One value is the research octane number (RON), which is determined with a test engine running at a low speed of 600 rpm. The other value is the motor octane number (MON), which is determined with a test engine running at a higher speed of 900 rpm. If, for example, a gasoline has an RON of 98 and a MON of 90, then the posted octane number would be the average of the two values or 94.

High octane gasoline does not outperform regular octane gasoline in preventing engine deposits from forming, in removing them, or in cleaning the engine. Octane requirements are based on Compression Ratio

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BTW, manual calls for 87 Octane and the FJR Compression Ratio ~ 10.8:1

Octane - Schmocktane - fillerup and ride

FJRottie said:

BTW, manual calls for 87 Octane and the FJR Compression Ratio ~ 10.8:1

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And there's a lot more to octane requirements that simple compression ratio: size of cylinders, water- vs. air-cooling, carbs vs. FI, camshaft timing, ambient conditions. I don't know about the current one, but my old R6 had 13:1 compression and run just peachy on the Yamha-specified 86.

This is a tired subject and just like there are people who believe fuel magnets really work, there are folks who are going to believe their stock engines run better on higher-than-specified octane. But if the engine isn't pinging, more octane does absolutely nothing.

- Mark

And there's a lot more to octane requirements that simple compression ratio

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Yes, I wasn't going to get into it.Just simply put, the manufacturer's manual will let you know your requirements.

But if the engine isn't pinging, more octane does absolutely nothing.

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+1

markjenn said:

This is a tired subject .... But if the engine isn't pinging, more octane does absolutely nothing.

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Yes it is (that's why they call it N-EPRT) -- but, nonetheless it's sort'a important (why else would they go to the trouble to state it (octane rating) on all gas pumps?

And....many don't know if their engine is pinging or not.

FJRottie: BTW, manual calls for 87 Octane

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That's minimum....

Some manufacturers have gone to switches that (you) select the octane you're using and the switch selects an appropriate ignition advance setting. Mo betta, may be?, a very high compression ratio (usually a good thing) along with a 'knock sensor' that will back-off the timing for cheapskates.

That way, we could all get by w/smaller engines -- might be hard on sales, tho....?

"85 octane or lesser?"

I burn 85 when available, but where does one get 'lesser'? South o the border maybe?

According to the API

(a decent read)

there is "... no practical way for the consumer to identify gasoline with a higher" octane

and "...there can be even larger differences in" octane "... between batches ... from the same refinery, between summer and winter ... or between brands..."

so -- per this vote -- Im in the minority here running 89 in the winter, 91 in the summer in all but the Aprilia which gets premi all the time.

Rickster said:

According to the API(a decent read)

there is "... no practical way for the consumer to identify gasoline with a higher" octane

and "...there can be even larger differences in" octane "... between batches ... from the same refinery, between summer and winter ... or between brands..."

so -- per this vote -- Im in the minority here running 89 in the winter, 91 in the summer in all but the Aprilia which gets premi all the time.

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While's its true that octane varies a bit from batch to batch, its also true that the octane requirements of an engine vary all over the map with load, ambient temperature, humidity, ambient pressure, air density, heat soaking of the engine, etc. 99% of the time, the FJR would run fine on 80 and less. So if you buy extra octane as "insurance" against subpar gas, it's not like your engine is going to start pinging dangerously the instant it drops below the mfg's recommendation - that recommendation has some built-in headroom for conditions that aren't very common. And engines can stand light pinging now and then without any problem - in fact, before FI and knock sensors, the car mfg's were advertising that light pinging now and then was a sign of "optimal performance".

Most motorcyclists can detect even a hint of pinging in an engine - the sound is quite distinctive. If you don't have a feel for this, then maybe paying an extra $.20 a gallon is not bad insurance. But I've owned five or six late-model Yamaha 4-cylinders and have never heard them ping unless they're really abused by lugging away from a stop with a ton of throttle and low revs. My assessment is that the Yamaha's recommendations already have a fair amount of headroom on them - the FJR engine is really in a fairly low-state of tune.

Air-cooled BMW R-twins are just the opposite - feed them the highest octane gas available, and almost all of them will ping under load if you get them really hot. I've heard the same about harleys. Big air-cooled pistons typically need all the octane you can muster.

Knock sensors are coming to bikes big time, so we'll all shortly be able to feed anything we want to these beasts and they'll compensate, like most cars do now. I've always been quite surprised at how primitive motorcycle electronic engine controls are compared to cars. (You get VVT on the cheapest Kia these days, but we're just now seeing it on the first bikes - the Concours.) I expect knock sensors to be commonplace in five years.

- Mark