Fuel Grade?

[black and silver twin]

...and/or less timing advance (gs500 has 40* = less) it can run on lower octane just fine and will actually run better with it.

But if the engine (any modern super sport) has high compression (12:1 is common= high), high cylinder flow (4 valves per cylinder = high flow), and/or lots of timing advance (+50* = alot) ...

Anybody know what the timing on a Bob Broussard ignition advancer is? 

jeff

it adds +5* for a total of 45*, still will run fine on regular assuming you have a decent afr.

[kylegod]

Take off the seat on my 98 gs500e and right there on the fender liner or whatever you wanna call it is a specs sticker. says 91+. Really didnt think it needed it but i do what it tells me to. check under your seat...

[Elijafir]

Take off the seat on my 98 gs500e and right there on the fender liner or whatever you wanna call it is a specs sticker. says 91+. Really didnt think it needed it but i do what it tells me to. check under your seat...

+1
Also, wanted to add:  I have no clue how the octane rating works.. I mean I understand the math, etc.. but, I have been to a lot of different parts of the U.S. and I have seen ratings everywhere from 85-101.  In Arizona we have 87 (regular,) 89 (plus,) and 91 (supreme.)  A couple of stations carry the 101 "racing" fuel.  It seems like the "west coast" is this way.. "mid-west" seems to be 85/87/89 and it's been a long time since I've been to the east coast but it seems like it's 87/90/93 over there (and maybe Colorado is like this?).. Does anyone know what's up with the inconsistency in octane ratings in the US? 

[black and silver twin]

altitude and temperature as well as emmisions regulations govern what octaine is sold in each state. higher altitude areas usually have lower octane fuel. hotter areas generally have higher octane, but emmisions regulations can throw off any patterns.

[LetsBeFriends]

i would just like to say that as a new rider i was told to use 93 and i have been but always had a itch in the back of my head telling me that it prob does not matter and this thread has since convinced me

[black and silver twin]

if the vehicle is designed for premium, use it, you will get more power/mpg and the engine will last longer (due to knock prevention), lower octane could cause engine damage.
If the vehicle is designed for lower octane (gs500 is designed for regular gas, its in the manual) use regular, higher octane wont hurt it but it wont be nesesary/optimum

[007brendan]

I've always wondered this, too.  My GS definitely says to use 91, but it uses some other unit besides octane, not sure if it's the same.  My truck's owner's manual says to use 87, and they both have essentially the same compression ratio, my truck is actually a little bit higher.

[Toogoofy317]

The Haynes manual says 91RON. Ironic that it didn't give out U.S octane.

Mary

[007brendan]

The Haynes manual says 91RON. Ironic that it didn't give out U.S octane.

Mary

Ah, RON, that was the unit.  According to wikipedia, 91 RON is about equal to 87 "octane" rating in the U.S.

In most countries, including all of those of Australia and Europe the "headline" octane rating shown on the pump is the RON, but in Canada, the United States and some other countries, like Brazil[4], the headline number is the average of the RON and the MON, called the Anti-Knock Index (AKI, and often written on pumps as (R+M)/2).

http://en.wikipedia.org/wiki/Octane_rating