Wasting my money?

[dbelch]

Trying to baby the '91..been burning premium..mainly to avoid ethanol.  I realize the higher octane burns slower..bike does tend to drag along until it gets into it's power band.  Does the stock FJ have the compression and timing to make any use of the higher octane?  Do any FJ drivers even experience knock on a hot day?  Do I save my money and burn the ethanol "enriched" lower grades?  Am I going to gunk up my cylinders with carbon on the lower grades? So many questions! 

[E Double]

I always use premium;  Its cheap insurance against pre detonation.  Plus the added octane makes for cooler head temps.  That right there, on an air cooled motor is reason enough for me to use the highest octane readily available.

Just an aside, my bike doesn't "drag along" at anything short of 2.5K rpm, and its an '84 FJ1100 that just tripped 78K miles a few days ago.  And it has 18/39 gears.

Whens the last time you synced/checked/overhauled your carbs?

[mst3kguy]

i've always been of the belief using higher octane than what is needed is a waste of $.  what's my definition of "what's needed"?  the lowest octane you can use that doesn't cause pinging.  that's my $0.02.

[RichBaker]

I've been running 87 octane for years, the Tucson heat does NOT bother the FJ at all.... Never heard a ping or knock from her.

[carsick]

The motor can handle 87 no problem. Higher octane CAUSES more carbon deposits, thus the addition (and marketing) of cleaning agents in the more expensive grades.
My '91 has suffered ping on one occasion. I ran it stop and go all day in a parking lot for a rider course, it was 80ish degrees. It was inevitable because a) tall gearing, 18-38 creates a lot of load starting out slow b) it had 87 octane in it, oops c) 5 degree ignition advance d) I ran it hot enough that fuel was boiling out the carb overflows. Never a problem when on the road though, even 2 up with mucho throttle application.

[FJTillDeath]

I use 95 octane not sure if thats good or bad but that basically all we have here plus the dealer recommended it so

I guess the general motion is to use whatever you feel comfortable with so long as its not too low of an octane. I dont know what the ping or tap is that other experience but what I experience is almost like a rattle a tiktiktiktiktiktiktik sound but I havent really n oticed anything wron with the FJ yet..mind you Ive only had it 2 months so I still have a lot to learn aboiut the bike

[Harvy]

I use 95 octane not sure if thats good or bad but that basically all we have here plus the dealer recommended it so

I guess the general motion is to use whatever you feel comfortable with so long as its not too low of an octane. I dont know what the ping or tap is that other experience but what I experience is almost like a rattle a tiktiktiktiktiktiktik sound but I havent really n oticed anything wron with the FJ yet..mind you Ive only had it 2 months so I still have a lot to learn aboiut the bike

Mate, that tiktiktiktik you hear us what is being talked about - pre-igniton.

get off the throttle and into a lower gear...


Harvy

[roverfj1200]

Here in OZ the ethanol add to the 91 octane fuel lifts the octane to 95.

I have always run E10 10% ethanol in my 88 when I can get it. Up to 120000km now with no ill affects.

I find that running E10 actually increases my mileage (go figure) and keeps water out of the system.

Cheers

[FJTillDeath]

At Harvey, what do you mean by pre ignition and when I actually notice this sound its normally when the bike is hot and normally when I am driving quite slow or reasonably in the low gears with very low throttle.

[Dan Filetti]

c) 5 degree ignition advance

Guessing it's mostly the advanced timing that caused the pinging -the excessive heat certainly does not help either, of course.  My Gixxer, which comes from the factory with advanced timing, requires at least 90 octane -says so right on the tank.  I've added lower octane in a pinch, and gotten away with it but if I were to get it hot as you did, I have no doubt there'd be pinging.

Dan

[andyb]

My Gixxer, which comes from the factory with advanced timing, requires at least 90 octane -says so right on the tank.

Double check that.  They may say it requires a motor octane of 90, or a research octane of 90.  Not the same as the numbers on a US gas pump.  For example, VP's MR12 (which is bad-ass fuel, but at $26/gal it better be...) has a motor octane of only 87, but on a gas pump it'd be marked as 93 (R+M/2, or AKI).  I'd imagine that it's running rather more compression than most FJ's though

If you can run pump 87 in your FJ and it runs well, then use it.  On exceedingly hot days, during stop and go traffic (more stop than go, face it), with massively advanced timing, or if you have a bucketload of miles and associated carbon buildup, you may notice detonation, usually going uphill at part throttle with a passenger would be the first you'd notice it.  Higher octane may help the bike start easier also.  That said, 93 will make less power than 87 will unless you've specifically tuned for it.  If you are using a power adder (forced induction or nitrous) you should definitely be using 93 or above such as C16 (motor octane of 117).

Tested at the dragstrip.  With 87 octane vs 104 octane, I lost a fairly large amount of power, in the range of 4-5% with no changes other than the fuel.

Ethanol won't hurt you, if you're prepared for it.  In fact, rejetting and running E85 will undoubtedly gain a significant amount of power (but the mileage will end up in the toilet!) due to the cooling effect in teh intake tract.  Gains in the range of 2-3% are what I'm hearing from guys at the track using and tuning for it on naturally aspirated bikes.

I would run 87aki pump gas from a reputable source (shell, BP, exxon/mobil) before I would run a "better" fuel from another source (93aki from Road Ranger, Caseys, other generic small gas stations).  And unless it was under the very specific conditions listed above, I'd always use 87 instead of 93, as well.  If your bike runs better on the higher octane, it's either tuned for it or the fuel is perhaps sketchy in your area.  87 is more commonly used by more people because of the cost, and as such it'll usually be fresher than a higher octane fuel in the gas station's tanks.

[FJTillDeath]

From what I have seen here we only have 95 and 93 octane, nothing lower and thats from shell bp caltex engen etc

[mz_rider]

From what I have seen here we only have 95 and 93 octane, nothing lower and thats from shell bp caltex engen etc

Most of the world uses RON rating, US uses AKI which is a lower figure for the same fuel - eg 95RON = 91AKI

Stuart

[Ganboy70]

I'm happy right in the middle at 89 mid-grade; it changes my plug colour slightly (for the better I think) and runs like a champ; my .02

[dbelch]

Thanks for the many answers...I think I'll slide back to a regular grade.  Sounds like the old FJ survived these many years on it to start with, and never seems to miss a beat.  Looking forward to lots of great rides before the sun sets on summer once again.  Is it worth running some carb clean up in it...had the carbs sync'd and cleaned, made a world of difference already.