Topic: High, Medium or Low Octane?

[Imago]

I know NOT to use ethanol, but what's the consensus on octane for a 1978 750F Super Sport?

It's FINALLY time to ride here in Saskatchewan!

[Bankerdanny]

Trial and error is the best way to figure it out IMO. There are lots of variables that impact how sensitive a bike is to octane.

I would run full tank of each starting with regular and see if you notice any change in performance. The stock engines don't have unusually high compression, so premium (high) octane shouldn't be necessary. 87 or 89 octane should work fine.

[cosmicvision]

For what it's worth, my 550 seemed to really respond better when I tried 92 octane; I get 93 when I can find it. Smoother pickup, and would go more like 110 miles rather than ~100 before hitting the reserve.

Could depend on a lot of things though. Heavy hand with the throttle, traffic riding vs freeway cruising, etc. Could all be placebo, I'd like it if it was. Paid over 4 bux for a gallon of the liquid gold yesterday. I have yet to run regular after cleaning carbs, etc...will try soon & post results.

[Muckinfuss]

Octane is octane, whether there's ethanol in it or not.  Anything under 10:1 compression won't benefit from anything other than regular.  You use higher octane to obtain slower burn rates for engines with higher compression, turbo, supercharger etc. because you are stuffing more into less and you don't need explosions happening.

[flybox1]

old topic.
http://forums.sohc4.net/index.php?topic=34103.25

non-ethanol 87
there are only 2 stations in my area, but i top off whenever i get the chance.
http://pure-gas.org

[bollingball]

On a stock motor 87 is all you need IMO. That is all I use I tried them all with a full tank and could not tell a bit of difference no pinging nothing. That is 10%eth. and with no eth. that I try to use
Ken

[TwoTired]

I know NOT to use ethanol, but what's the consensus on octane for a 1978 750F Super Sport?

It's FINALLY time to ride here in Saskatchewan!

What measurement method is used on the pumps you frequent?
RON, MON, AKI, or PON?

The owners manual for my 77 CB750F states:
 Use low lead or regular gasoline with a Research Octane Number of 91 or higher, or a Pump Octane Number of 86 or higher.

Higher octane gasoline does not contain any more energy per volume than lower ones.
The high dollar outlay does often lead to placebo effect, though. (I paid more, I must be getting more.)

[70CB750]

flybox beat me to it - check the web page if you have a station with real gas in your area.

[iron_worker]

Just as an aside ... it's been riding weather for at least a month! What have you been waiting for?!

IW

[Lostboy Steve]

old topic.
http://forums.sohc4.net/index.php?topic=34103.25

non-ethanol 87
there are only 2 stations in my area, but i top off whenever i get the chance.
http://pure-gas.org

hahaha NJ isnt even on their map. This #$%*ing state blows more every day.

[Jim Harris]

I asked the same question a couple of months ago and got a very helpful and knowledgeable response from bbi.

See response posted by "bbi", dated 3/31

[Bailgang]

 All octane means to any of us who are not chemists is a number that gives a value to how stable (key word is stable) a fuel is and shouldn't be confused with how fast it burns. In a cylinder that's firing like it should with a controlled burn (no detonation) then 85 octane gas wont burn any faster than 91 octane pump gas and if the engine runs just fine on 85 then it won't see any HP benefit running 91 octane either. Sunoco Maximal 116 and 117 octane race gasoline is the highest octane gasoline Sunoco makes, it's also the fastest burning gasoline they make so higher octane/slower burn theory doesn't fly.

[Retro Rocket]

Use what ever makes it run its best, avoid any fuel that causes "pinging" or 'Knocking" under load, contrary to what TT says , i have run higher octane fuels in older vehicles with good results, i had a 6 cylinder car that pinged under load, it not only ran better and didn't ping with higher octane, it also got better fuel economy. Use what ever makes your bike run best.... I also avoid ethanol, it absorbs water and helps rust out your tank, it gets worse economy and if left in the tank and carbs for any length of time causes other problems as well....

[Jerry Rxman Griffin aka MuthaF'er]

If you use pump gasoline you will be fine regardless of what octane. Sometimes higher octane is advertised with more 'beneficial' additives. If you feel that extra cleaner might help then spend yer dough on it. This needs to be turned over to Mythbusters 

[Xnavylfr]

iF YOU really WANT some octane boost , go to a small local airport and buy 5 gallons of AVGAS=110/115 octane LL , for every 5 gals of 87 octane add 1/2gal of AVGAS , trust me YOU'LL notice the difference. this combo come out to be about 100 octane. I used to run this combo when I ran my Z(1100cc) on the 1/4

Xnavylfr(CHUCK)

[Stev-o]

Running 93 makes me feel better but honestly, I can't tell the difference.

I hate ethanol but have no choice in my area.

[Lostboy Steve]

If you use pump gasoline you will be fine regardless of what octane. Sometimes higher octane is advertised with more 'beneficial' additives. If you feel that extra cleaner might help then spend yer dough on it. This needs to be turned over to Mythbusters 

Agreed. I have 100 octane unleaded here at a local sonoco, I can also get 110 112 ect, leaded from the local race track. I'm starting to think 87 may be the way to go. I bet the 87 now a days is closer to "gas of the day".

[goldarrow]

I've been using 91 since engine, clocking at about 35 mpg 60mph average speed on the last weekend GZ ride 300 miles.  May be I should try 87 octane in hopes of better mpg?

[desertw0lf]

We have no stations in Las Vegas that sell gas without ethanol blended into it. That makes me sad for my future build's health

[70CB750]

Running 93 makes me feel better but honestly, I can't tell the difference.

I hate ethanol but have no choice in my area.

I would think that's funny - considering you live in Texas 

The area of Metro DC is totally without pure gas, but further you go to rural VA, more luck will you have finding it.  I just discovered Ma and Pa shop 18 miles from me that sells ethanol free gas.  I will be going there a lot.

[trueblue]

My 650 doesn't like anything less than 96RON.  On anthing less it pings its head off when I load it up .

[matt mattison]

old topic.
http://forums.sohc4.net/index.php?topic=34103.25

non-ethanol 87
there are only 2 stations in my area, but i top off whenever i get the chance.
http://pure-gas.org

hahaha NJ isnt even on their map. This #$%*ing state blows more every day.

NJ= Pay more, get much less and like it!!

[bollingball]

A good place to find no ethanol fuel is a boat dock or a bait store.
Ken

[Stev-o]

A good place to find no ethanol fuel is a boat dock...

Took my boat out on Memorial Day, the pump nearest my boat dock had a label on - 10% ethenol, I was bummed.

My boat has a 496 V8 with fuel injection, started right up after sitting for 8 months, so it doesnt seem to mind the crap fuel.

[750K]

I run premium but only from chevron or shell locally, their premium blends are ethanol free around here. I used to run reg but switched once I found out about the ethanol free ones, that's the only reason I pay more.