85 Octane in The FJR

[Bounce]

No refunds on your tuition into the school of life. But at least you learned it in only 1 summer.

 

[FJR Bill]

Topic has already been covered very well. Key point: if it doesn't knock, it's OK. If my memory serves me, back in the 50's and 60's gasoline commercials were advertising their higher octane ratings inferring the very false impression they delivered more power. Me thinks this is what started the myth.

Bill

 

[LAF]

Amarillo TX, and Oklahoma City, OK has 86. I used it! Bike did not explode! 575 miles of just blowing gas through at 75-85 miles an hour. How could it matter?

Just strange traveling and seeing the various gas octane available. Here in Oklahoma at the station I stopped at they looked at me like I was crazy when I mentioned ethanol. He said the Shell uses that stuff, but we dont.

 

[MajBach]

No issues with lower octane unless there is. It's an thing within fuel to prevent pre-detonation (knock). If you don't have knock with the lower octanes then there's no need to spend more money on the higher ones. The benefit is that the octane works to resist detonation, so that means it's harder to set off in the combustion chamber the higher the rating. Some (like you noted) get better mpg from lower octanes than higher ones. So... better mpg, lower price, no knock: the only reason to buy higher octane if if the motor is a higher compression combustion chamber that requires it.

for years i was mislead into thinking that higher octane meant more "power" when it's nearly the opposite. a gallon of one has no more energy than a gallon of the other. it's also not "better". it simply resists pre-detonation at higher compression ratios. so why spend more for something you don't need?

i even bought a tank of 101 octane PUMP gas when in OKC once (there's still one place on the north side that sells it). the reason? so i could mention it in threads like this. it got no better or worse mpg in my 2008 Subaru STi than the 93 octane its high-compression, turbo, stage 2 motor was tuned to use (ie: it doesn't knock at 93 octane, so it also won't knock at 101 at twice the price). meanwhile it cost me more than $6 a gallon for the bragging rights.

I agree with everything you stated here and want to add something (without reading below if someone already has). I too, as a teen many years ago and when there was still leaded gasoline ran hi octane believing it was worth the extra $$$ and you more than made up for it with improved fuel efficiency. Being the geek I was (as I am sure most here can relate ) I meticulously compared mileages from a tank of regular to a tank of high octane and saw no difference. This disappointed me obviously as I now felt like I didn't know what I thought I knew that no one else knew, ya know? More research on the topic revealed in a nutshell that adding octane to a car that doesnt require it is like taking too many vitamins.

But there is an exception.

Back in the day - where cars were mostly naturally aspirated, ignitions had coils and there were no computers in your car, it was pretty easy to tell when you needed more octane in your fuel by the tell-tale 'ping' ( or a hole in your piston ). But, with today's anti knock sensors, such is not the case. This was made all to apparent to me when I used a mid 90s Honda Accord to tow a boat far to heavy for it. With my older (and simpler car) that normally ran on low octane gas, when I towed with it I could hear the pinging when going up hills. This was eliminated of course with hi test gas. I never heard this with the newer Accord - because it was changing the timing to protect the engine. The result - on my usual very hilly road to my favourite fishing hole - was very poor fuel economy. That is, until I ran higher octane gas. The increased mileage was incredible. However, had I not done the math at the pumps, I would have never realized the advantage of the better gas in that scenario.

I dunno if the FJ'er has antiknock sensors..or if you'd even be able to hear when you're running to low an octane gas. I'll leave that up to you guys to ponder. I just always run high octane from Shell so I never have to worry about it. (And yes, it IS different here and NOT as waste of $$$. Super gas from Shell CANADA has no ethanol in it and it DOES improve performance and mileage. I travel south of the border often enough to notice the difference). :blind:

 

[Bugnatr]

Both times I filled with 85 in Utah by mistake(I grabbed the reg, pump) my bike ran like crap off the line. Once I was moving it was fine but I did burn off half a tank and add prem. to get it back to normal. Of course this is with the mighty powerful Gen I, most likely those slow gen II's it would not matter.

 

[RadioHowie]

Both times I filled with 85 in Utah by mistake(I grabbed the reg, pump) my bike ran like crap off the line. Once I was moving it was fine but I did burn off half a tank and add prem. to get it back to normal. Of course this is with the mighty powerful Gen I, most likely those slow gen II's it would not matter.

 

[Bugnatr]

Both times I filled with 85 in Utah by mistake(I grabbed the reg, pump) my bike ran like crap off the line. Once I was moving it was fine but I did burn off half a tank and add prem. to get it back to normal. Of course this is with the mighty powerful Gen I, most likely those slow gen II's it would not matter.

Yep, those poor gen II guys.

 

[not2shabby]

I run 85 octane and I have had some engine knock at low rpm in 2nd and 3rd gear. Nothing that an upshift wont fix, but it is there.

I think you meant downshift, didn't ya?

 

[SkooterG]

I run 85 octane whenever it is available (at the higher elevations) with no difference whatsoever.

 

[A41Billy]

I would rather run lower octane and save money. If you want ethanol free gas around here it has to be premium and only a few stations have it. How many of you are avoiding ethanol?

 

[garyahouse]

I dunno if the FJ'er has antiknock sensors..or if you'd even be able to hear when you're running to low an octane gas. I'll leave that up to you guys to ponder. I just always run high octane from Shell so I never have to worry about it. (And yes, it IS different here and NOT as waste of $$$. Super gas from Shell CANADA has no ethanol in it and it DOES improve performance and mileage. I travel south of the border often enough to notice the difference). :blind:

I don't believe the FJR has knock sensors. Reason being, mine will knock on 87 regular when it's good and hot, running at really low rpms and a lot of throttle. When I let the clutch out too fast in stop and go traffic, thus lugging the engine, if I give it too much throttle will produce knocking every time. The cure? I don't give it a great deal of throttle under those conditions.

Gary

darksider #44

 

[SkooterG]

The FJR most definitely does NOT have knock sensors.

 

[Full House]

Before ethanol, the general consenses was that the lower octane fuels stayed fresh longer than the higher octane fuel. Now ethanol doesn't stay fresh without stabilizer. I use Sea Foam, best I have found.

 

[GPRIDER]

The octane is not the problem, it's the ethanol. All my vehicles would get better mileage without it. I've been running all octanes from the lowest to the highest over the last 25 years or so and could tell no difference. It will not give you any extra hp.

GP

 

[tcfjr]

I got a tank-full of 85 in Tonopah, Nevada yesterday -- a town Skooter is familiar with, at 6,000 feet -- and had no problems running at "central Nevada pace" down into Baker.

 

[garyahouse]

Before ethanol, the general consenses was that the lower octane fuels stayed fresh longer than the higher octane fuel. Now ethanol doesn't stay fresh without stabilizer. I use Sea Foam, best I have found.

Sea Foam: I always thought ya used that stuff to clean out the injectors. Do they make more than one product, or do you use it as a stabilizer over the winter months... just like many use Stabil?

Here's an interesting question: if alcohol is so detrimental to performance, how is it that it makes so much more power than gasoline at the dragstrip? Anybody out there know the details about compression ratios and fuel/air mixtures for pure alcohol? I'm a little rusty, but I believe the rate for gas is around 14 to 1 by weight, and alcohol is around 8 to 1. Though alcohol doesn't pack as much punch per ounce as gasoline, it's proper fuel/air ratio requires a lot more of it during each burn cycle. Simple math, just under twice as much fuel going into the engine produces more power per stroke. However, if you're measuring by the gallon, forget about mileage. And if your engine is set up for gas, forget about mixing the alcohol at it's optimum ratio. Net result? Less power and less mileage.

Gary

darksider #44

 

[RadioHowie]

Here's an interesting question: if alcohol is so detrimental to performance, how is it that it makes so much more power than gasoline at the dragstrip?

Gary

darksider #44

Gary, just a guess here, but I'm speculating alcohol is used at the dragstrip since those cars are running MAJOR compression with superchargers...probably around 20:1 compression ratios, and that alcohol works MUCH better than gas at preventing pre-ignition due to the high compression ratios. It's all in preventing supercharger launching off the top of motors.

Plus, since they suck down about 13 gallons of fuel in a 1/4 mile run, I don't think the BTU-per-gallon efficiency is an issue.

 

[art miller]

Like most of the posts, I use only 85 octane or regular gas. I have been to 11,000 elevation and hard throttle with no negative effects. Octane determines at what temp the fuel ignites. Depending on the compresson ratio and tuning of the engine octane level is specified. Computerized fuel injection compensates for the altitude variation. Don't be fooled by the hype on 91 octane.

 

[stealth1]

I have personally never seen an owners manual for any vehicle that recommends 85 octane gasoline. Around here every station has it and I have never noticed any difference in performance or mileage when using it in my cages but have been reluctant to run it in the FJR.

I live at 5800' elevation. Rides frequently vary from 3000' to 11,000'.

 

[Greg 03]

I've also been burning premium gas in all of my toys, dirtbike, four wheeler, bandit, etc. to avoid ethanol. I've been told "E" is horrible for motorcycles. The one thing I couldn't glean out of this thread was if higher octane gas hurts the FJR or not. If not I think I'll still try to avoid putting corn in my motor and leave it for feeding hogs like it should be used.