Effects of high octane fuel

Hi All,
Been fighting my 82 550 as of late - just having some issues getting the carbs dialed in perfectly. I had a thought this morning though...
I have an 09 Fat Bob that runs 91 octane...I had a fuel pump regulator act up, so I had to drain some of the fuel out to work on it. That fuel went into my gas can in the garage. I ended up forgetting it was 91 octane and put it in my 550.

Now, the good part is there is no ethanol...but I am not sure the effects high octane would have on the 'ol 550. I'm not worried it'll ruin anything per se, but what would be the effects of having this higher octane fuel in an old bike that I believe prefers 87 octane (per the manual)?

Your bike should love it. I always run 93 octane in my KZ650. Ed

General rule of thumb is to use the lowest octane fuel that doesn't cause knocking. If that's 87 then run that. Using higher octane fuel won't hurt but it won't add any value either. Pretty much just a money waste.

crap.
I was hoping you'd say that the higher octane would have a slower burn, causing the timing to be a little off and not run quite right

apbling wrote: crap.
I was hoping you'd say that the higher octane would have a slower burn, causing the timing to be a little off and not run quite right

As I understand it, higher octane does burn slower. That's why it suppresses knock. It actually has less heat energy than regular fuel. Regardless, the fuel won't cause your timing to be off. However, with high octane fuel you can advance the timing a little compared to regular fuel without causing detonation.

Nessism wrote:

apbling wrote: crap.
I was hoping you'd say that the higher octane would have a slower burn, causing the timing to be a little off and not run quite right

As I understand it, higher octane does burn slower. That's why it suppresses knock. It actually has less heat energy than regular fuel. Regardless, the fuel won't cause your timing to be off. However, with high octane fuel you can advance the timing a little compared to regular fuel without causing detonation.

That's why I almost always mix 89 silver and 93 Gold for a mix that comes out to around 91......... was surprised after using high oct all my life reading that it had a little less energy over reg and if you don't need it your wasting money and getting a little less performance.

KZB2 650 wrote:

Nessism wrote:

apbling wrote: crap.
I was hoping you'd say that the higher octane would have a slower burn, causing the timing to be a little off and not run quite right

As I understand it, higher octane does burn slower. That's why it suppresses knock. It actually has less heat energy than regular fuel. Regardless, the fuel won't cause your timing to be off. However, with high octane fuel you can advance the timing a little compared to regular fuel without causing detonation.

That's why I almost always mix 89 silver and 93 Gold for a mix that comes out to around 91......... was surprised after using high oct all my life reading that it had a little less energy over reg and if you don't need it your wasting money and getting a little less performance.

Then why do they use racing fuel 100 octane in race bikes & cars, if you get less performance , ? :huh:
Pete

Pete - I think he meant that if your engine isn't set up to take advantage of the higher octane you'll get worse performance?

I think IF there was EVER a day my 'ol 550 would have seen the track, its long long long ago lol.

pete greek1 wrote:

KZB2 650 wrote:

Nessism wrote:

apbling wrote: crap.
I was hoping you'd say that the higher octane would have a slower burn, causing the timing to be a little off and not run quite right

As I understand it, higher octane does burn slower. That's why it suppresses knock. It actually has less heat energy than regular fuel. Regardless, the fuel won't cause your timing to be off. However, with high octane fuel you can advance the timing a little compared to regular fuel without causing detonation.

That's why I almost always mix 89 silver and 93 Gold for a mix that comes out to around 91......... was surprised after using high oct all my life reading that it had a little less energy over reg and if you don't need it your wasting money and getting a little less performance.

Then why do they use racing fuel 100 octane in race bikes & cars, if you get less performance , ? :huh:
Pete

Because race bikes/cars have higher compression, boost, or nitrous.

The drag racers on the newest 'busa's and liter bikes and stock engines actually get better times when the retuned for 87 octane. "Premium" doesn't necessarily mean better. You run the fuel your engine needs.

pete greek1 wrote:

KZB2 650 wrote:

Nessism wrote:

apbling wrote: crap.
I was hoping you'd say that the higher octane would have a slower burn, causing the timing to be a little off and not run quite right

As I understand it, higher octane does burn slower. That's why it suppresses knock. It actually has less heat energy than regular fuel. Regardless, the fuel won't cause your timing to be off. However, with high octane fuel you can advance the timing a little compared to regular fuel without causing detonation.

That's why I almost always mix 89 silver and 93 Gold for a mix that comes out to around 91......... was surprised after using high oct all my life reading that it had a little less energy over reg and if you don't need it your wasting money and getting a little less performance.

Then why do they use racing fuel 100 octane in race bikes & cars, if you get less performance , ? :huh:
Pete

First of I wanta say I'm not even close to a expert just stating from a "limited amount" of reading I have done on it (and talking to a old racer)..... and Apbling's right I was talikng more on a stock 9 - 9.5 to 1 engine with stock timing and small stock cams ....... I agree the 98 to 100 octane fuel is needed for a 12 or 13 to 1 motor advanced 2 to 4 degree's with cams..... In the old days you could get 101 octane Sunoco at the station for 35 to 40 cents a gal and I ran more than a few tanks of that through my Chevelle, GTO and 57 Chevy ......... the Chevelle really needed it cause it had 12.5 to 1s and a zl1 cam. :woohoo: ....... I also wanta say I've bought more than a few gals of racing 100 octane gal around where I live for my 650 too and it ran exc so I'm not cutting it down at all.

tachrev wrote:

pete greek1 wrote:

KZB2 650 wrote:

Nessism wrote:

apbling wrote: crap.
I was hoping you'd say that the higher octane would have a slower burn, causing the timing to be a little off and not run quite right

As I understand it, higher octane does burn slower. That's why it suppresses knock. It actually has less heat energy than regular fuel. Regardless, the fuel won't cause your timing to be off. However, with high octane fuel you can advance the timing a little compared to regular fuel without causing detonation.

That's why I almost always mix 89 silver and 93 Gold for a mix that comes out to around 91......... was surprised after using high oct all my life reading that it had a little less energy over reg and if you don't need it your wasting money and getting a little less performance.

Then why do they use racing fuel 100 octane in race bikes & cars, if you get less performance , ? :huh:
Pete

Because race bikes/cars have higher compression, boost, or nitrous.

The drag racers on the newest 'busa's and liter bikes and stock engines actually get better times when the retuned for 87 octane. "Premium" doesn't necessarily mean better. You run the fuel your engine needs.

Your comparing a new busa which the motor was built to run on unleaded fuel to our old bikes which were built to run on leaded fuel, racing fuel is leaded & I remember back in the 80s we would put the Purple Martin race fuel in our stock bikes every once in a while if we were going to race some one on the streets of Chicago & it made a difference
Pete

Octane is octane. If you aren't detonating, higher octane won't make more power by itself no matter what the vintage or engine design.

Lead in fuel was an octane booster and a lubricant or sorts.