What Octane to run?

[Jim/Maine]

Interesting read guys, and way above my pay grade. I am curious that compression ration has not been mentioned?
I have always attributed the relatively low compression R3 to working well with lower octane fuels. And my seat of the
pants cannot seem to get more out of higher octane and I never have knocking. Ethanol is another
matter -- total bs in all ways. I use a stabilizer which, theoretically, modifies the Ethanol, with every fill up. I do not recommend
use of aviation fuel which is 100 octane, 100LL (low lead) which is anything but low lead. Obviously the lead is incompatible with
catalytic converters but I have heard that it can also not work well with modern engines, valves mostly, designed to run with no lead.
My choice of gas is usually to use a busy station with lots of volume to preclude stale gas, and I usually go mid range as that, I
think, is a mix of the lower and higher octane tanks. Seems to be the case especially where it is obvious there are three octane
options but only two tanks. But the above is with a -- so far -- stock engine.

 

[Tripps]

Bob Carpenter, when I asked about octane, said it would run a little stronger with 87 octane. Parallels a test which someone did on the GSXR forum I used to belong to. They are tuned for 87 octane stock, a guy did back to back dyno runs with regular and premium, , the premium dropped 2 or 3 horsepower from the regular.

 

[teraeric]

Bob Carpenter, when I asked about octane, said it would run a little stronger with 87 octane. Parallels a test which someone did on the GSXR forum I used to belong to. They are tuned for 87 octane stock, a guy did back to back dyno runs with regular and premium, , the premium dropped 2 or 3 horsepower from the regular.

this is because lower octane gas burns faster... you get best performance out of fuel that's right at the edge of exploding (which is just burning a little too fast) so higher octane than required saps (potential) power...

this has been gone over and over, but a low compression, large volume cylinder motor like the r3 is made to run on low octane gas... there's a reason they run 2 spark plugs (another physics lesson in itself as to why that's not a good thing) and low octane - they need all hell to break loose (well, juuuust short of all hell) in order to make as much power as possible from the given configuration...

i always burn the lowest octane my vehicle will run... lots of it...

 

[vanguard138]

For purposes of my annual bonus, I'd prefer you all to buy V-Power in large quantities...but it really doesn't help the bike, and typically decreases fuel economy on a low compression engine. Across most brands of fuel, the additives are the same across their range, except the octane booster. NEVER buy "unbranded" gasoline for any vehicle (generally seen at large grocery store or department store parking lots). There is typically little or none of the additives (detergents) and they're pretty helpful.

MarvinM

never ceases to amaze me that you will have a Shell or BP station on a corner (branded fuel) and a Speedway, or grocery store station on the other corner (unbranded fuel), and the price is the same and the uneducated buy the unbranded fuel.

 

[Pres10]

this is because lower octane gas burns faster... you get best performance out of fuel that's right at the edge of exploding (which is just burning a little too fast) so higher octane than required saps (potential) power...

this has been gone over and over, but a low compression, large volume cylinder motor like the r3 is made to run on low octane gas... there's a reason they run 2 spark plugs (another physics lesson in itself as to why that's not a good thing) and low octane - they need all hell to break loose (well, juuuust short of all hell) in order to make as much power as possible from the given configuration...

i always burn the lowest octane my vehicle will run... lots of it...

You're exactly right. That's also a main reason for quick burn combustion chambers in modern engines. Any way to speed up the combustion process is a benefit. On our bikes it's the dual plugs. Because of this many modern engines run higher compression without the need for as high an octane as was needed, say back in the 60's and 70's.

I don't have any trouble finding alcohol free fuel out here. Normally I run 87 in my stock Rocket. When riding in the mountains above 6500 ft. I often run 85 octane fuel. Never any problems and the 85 does give a little better fuel economy.

Next spring I am planning on my bike requiring premium fuel. Plan to do a Carpenter 240 on it this winter.

 

[Tripps]

fuel economy.

Next spring I am planning on my bike requiring premium fuel. Plan to do a Carpenter 240 on it this winter.

Bob Carpenter recommends 87 for his 240 package.

 

[Pres10]

Bob Carpenter recommends 87 for his 240 package.

Maybe I won't need premium fuel next year.

 

[Rick McC.]

I run 90 octane in my bike, boat (and lawn mower, generator, pressure washer, etc.) because the store four miles from here sells it, and it's ethanol free.

It's called "Rec 90;" for use in recreational vehicles, mostly boats, which ethanol wreaks total havoc on.

The state of Fla. requires that fuel for vehicles operated on the roads down here contain 10% ethanol as an "environmental" benefit.

What a total load of crap!

The Rocket (and previously my Bonneville) sure runs great on it!

Rick

 

[txaggie]

My dealer said to run 91 octane. I don't think he owns a gasoline company, but maybe he does.

 

[Rick McC.]

My dealer said to run 91 octane. I don't think he owns a gasoline company, but maybe he does.

My 2012 R3R Manual notes the fuel requirements as "87 octane minimum."

Rick