What Octane?

[stormi]

Hey!

Reading the manual for the Bandit, it says that it wants 91 octane.  The manual for my CB900F says minimum 86 octane.  This surprised me, so I asked the Honda dealer about it, and they said just run regular. that it's not a performance engine?!?!  I'm thinking, it's more performance than the Bandit is, so why does it require less octane?  Which brings me to my question.

What Grade of fuel does everyone here use in the B4?  And does anyone fill up with any "alternate" fuels, such as Ethanol blended, etc?

[erik]

I just use 91 octane.

[duane]

The manual spec 91?  Oh....
In the past, I thought the Bandit ran great on regular gasoline.  My VFR800 specs regular.  (what is regular anyway, 87 89?)  Isn't the octane dependent on compression ratio and timing?

[b4cruz]

CB900F 10.8:1
gsf400  11.8:1

i use 91 in my b4, and i get power and mpg
crappy &/or dirty gas gets a bit lower power and lower mpg

[Red01]

I'm thinking, it's more performance than the Bandit is, so why does it require less octane?  

The Hornet engine is >2X the size of the B4    

It requires less octane because it is a detuned version of the CBR engine.
While the B4 engine is a detuned GSXR4 motor, it's not detuned nearly as much as what Honda did with the CBR/919 (and Suzuki did it similarly with the 600 & 1200 Bandits from their GSXR kin).

[stormi]

I'm thinking, it's more performance than the Bandit is, so why does it require less octane?  

The Hornet engine is >2X the size of the B4    

It requires less octane because it is a detuned version of the CBR engine.
While the B4 engine is a detuned GSXR4 motor, it's not detuned nearly as much as what Honda did with the CBR/919 (and Suzuki did it similarly with the 600 & 1200 Bandits from their GSXR kin).

Nuh uh,.. Honda says "Retuned"    

So,... Dita's engine has a higher compression ratio, so she needs more Octane... simple as that?  

hmm,.. at $1.15/l she's going to be significantly more expensive to run soon than the Hornet.

[stormi]

The manual spec 91?  Oh....
In the past, I thought the Bandit ran great on regular gasoline.  My VFR800 specs regular.  (what is regular anyway, 87 89?)  Isn't the octane dependent on compression ratio and timing?

    I did the same thing when I read that in the manual.  

"Regular" = 87 octane,.. here anyway.

[Erikkt]

I use 95 octane, we don't have anything lower here in Norway, only 95 and 98.

[Red01]

That's because Europe uses a different octane rating system than the US & Canada.

[KSUGreggy]

out here in the boonies in kansas most of our premium fuels have something like 10% ethanol in them.

When i had my b4 i ran the 91 octane w/ 10% ethanol no problems through several tanks.

[interfuse]

My shop manual for the B4 only calls for 87 octane and thats what I use.

"Use only unleaded gasoline of at least 87 pump octane by the (R + M) / 2 method or 91 octane or higher rated by the Research method"

For more information on octane ratings Petro Canada has a good FAQ:
http://www.petro-canada.ca/eng/prodserv/fuels/6823.htm#gasthree

[stormi]

My shop manual for the B4 only calls for 87 octane and thats what I use.

"Use only unleaded gasoline of at least 87 pump octane by the (R + M) / 2 method or 91 octane or higher rated by the Research method"

For more information on octane ratings Petro Canada has a good FAQ:
http://www.petro-canada.ca/eng/prodserv/fuels/6823.htm#gasthree

I just looked at that too.  Interesting that the Shop Manual and the Owner's Manual would both read differently.

Thanks for the link!  I think I'm as confused as ever, but it was an interesting read.  Especially the part about needing more octane as the engine gets older.  

So what I read from this is that 87 - 91 Octane will likely not make much difference, but 91 is recommended for the higher compression of the engine? She's never knocked or pinged on the 87 I've been feeding her...

[interfuse]

I just looked at that too.  Interesting that the Shop Manual and the Owner's Manual would both read differently.

Yes, thats strange. I don't have an owners manual so I've never thought about it.

So what I read from this is that 87 - 91 Octane will likely not make much difference, but 91 is recommended for the higher compression of the engine? She's never knocked or pinged on the 87 I've been feeding her...

I only use 87 octane from large chain stations -- petro, shell or esso here -- noname gas scares me. Never had any knocks or pings... I've tried higher octane fuels and didn't notice any difference other then my wallet felt lighter...

[Red01]

My shop manual for the B4 only calls for 87 octane and thats what I use.

"Use only unleaded gasoline of at least 87 pump octane by the (R + M) / 2 method or 91 octane or higher rated by the Research method"

For more information on octane ratings Petro Canada has a good FAQ:
http://www.petro-canada.ca/eng/prodserv/fuels/6823.htm#gasthree

I just looked at that too.  Interesting that the Shop Manual and the Owner's Manual would both read differently.

Thanks for the link!  I think I'm as confused as ever, but it was an interesting read.  Especially the part about needing more octane as the engine gets older.  

So what I read from this is that 87 - 91 Octane will likely not make much difference, but 91 is recommended for the higher compression of the engine? She's never knocked or pinged on the 87 I've been feeding her...

Not having a B4 - or it's manual, I was relying on what you folks were telling me the book said, but now that it's been clarified, I went back and edited my last post.

The B4 should run on regular, just like it's larger kin.

What the book is telling you is in countries that use the R+M/2 octane rating method (USA & Canada), you use 87 - or regular. In countries that use only the Research Octane Method (ROM) you still use regular, but ROM has a higher number, so the regular pump is marked 91, but it is still the same octane as a R+M/2 pump that's marked 87.

I hope that's clearer...

[stormi]

The B4 should run on regular, just like it's larger kin.

What the book is telling you is in countries that use the R+M/2 octane rating method (USA & Canada), you use 87 - or regular. In countries that use only the Research Octane Method (ROM) you still use regular, but ROM has a higher number, so the regular pump is marked 91, but it is still the same octane as a R+M/2 pump that's marked 87.

I hope that's clearer...

alright,.. what that means is that the guilt feelings I felt over all the carbon and stuff in her engine being from me giving her the "cheap" gas,.. were unfounded.    

I found it interesting that the owner's manual doesn't clarify the 91.  Many (most) owners would never see the service manual...