Best High Octaine to Run

[Tsani]

I would say you got it.

[76shuvlinoff]

..... so therefore if a motor does not need higher octane you are sacrificing miles per gallon (efficiency) by using it unnecessarily

... correct?

[takwolf]

Correct Shovel!

[Little Al]

i was taught too many years ago to remember that the "best" gas to use (in any vehicle) was the lowest octane that didn't cause detonation (ping)

[harley1450000]

B.P.  93  about the best where i live

[barny7655]

i have a 44 gal of av gas 100 octane ,use it to clean the lawn mower out, and add it  to the bike , what you dont use goes out the exaust , it will clean the combustion chambers dries them out, then using the water injection through throttle body you have nice clean pistons , it does take longer to burn a high octane fuel but on high CR motors, its what it needs to complete that burn,but alass it cant be got every where so go with out the higher octane , you do notice that the oil is cleaner on changes using a higher octane fuel , like using propane  gas on a car ,clearer, and alot cleaner, like the old days when we had leaded fuel around 98 octane , good post cheers  BARNY

[Bruno-Katz Fokkerpilot]

Didn`t actually mean that 99 octane will make the bike faster, as stated by other guys here, it gives a much more efficient burn in the head. This, i`ve found does give a much smoother acceleration and far more comfortable cruising than our standard 95 octane. At 65 or 70 mph, i`ve cocked my head to one side and listened to the exhaust note and i can hear a noticeable difference and feel a stronger running engine when i fill up with 99 octane as opposed to our 95.
I had no idea that octane ratings are different around the world, all i`ll say is that 99 octane gives me the impression that the bike runs much better and feels more alive than when i use 95.
Maybe i have an over active imagination but the physics of the thing, dictate that the engine should run better with higher octane fuel.

Please don`t move here just to try this theory out.........you`ll die from Swine Flu. 

[Phu Cat]

Maybe i have an over active imagination but the physics of the thing  Now yer on to somethin Pilot!  I wondeer if that isn't how many myths get started.  A guy reads or hears a statement but sees the physics of it just slightly differently in his mind's eye and next thing ya know a new 'old wives tale' has been created.

Little Al had the answer actually:  Higher octane simply cuts down on a fuel's likelyhood of premature ignition from something other than the spark plug.  Higher octane does not add extra power.  In fact, more octane than you need slightly! reduces the available power.  Higher octane does not run cooler, burn faster, or ignite more easily.  I realize this is now second hand information being given to you but it was given to me by the engineer in charge of gasoline blending when I was in the industry.

PC

[ejk_dyna]

<<I've never seen octane make anything faster.>>

<<Higher octane does not run cooler>>

While these comments are true for the majority of builds...they are not true for every build.

An example of this is a "bleeding edge" high compression build which has to have major ignition retard and possibly richer than optimal fuel to eliminate detonation.  This build runs well and produces decent power using 91 octane gas.  Now change fuel to 100 octane unleaded and retune (more advance, less fuel) and you will definitely make more power, run cooler and probably get better mileage.

[Phu Cat]

change fuel to 100 octane unleaded and retune 

Is that a fair comparison?

PC

[apendejo]

Just for the heck of it I once filled my tank('03 Ultra) with 76 Union 104 race gas. Got about half a block down the road and the motor started running rough and lumpy It also felt like it was 8 stroking at stoplights the way it does when the motor is too hot.
I got it home and pulled the plugs and they were all sooted up, on the verge of fouling out.
I drained the gas, went and got a couple of gallons of 91 and the motor and plugs cleaned right up.
Learned my lesson. I gave the race gas to my gardener.
AP

[ejk_dyna]

<<change fuel to 100 octane unleaded and retune>>  

<<Is that a fair comparison?>>.

OK I see what you are saying.  I agree that a well tuned bike with fixed ignition timing using 91 octane will not benefit at all from higher octane fuel by simply changing the fuel and could actually run worse due to the burn characteristics if the octane differential is large.

I was just commenting that it is not absolute...but a retune to take advantage of the higher octane would be necessary.