[92GSX750]

So, these bikes only need 87? I will be the first to admit I'm a newb when it comes to bikes. Always messed with old cars and trucks, mostly trucks with worked motors. Learned something new here

[arsenic]

These engines have an 11.3-1 compression ration. That's REALLY low compression. You need to use higher octane fuel for higher compression engines. Yes, the engines are designed to run on 87.

[TRPUT]

Must be that we are upside down in Oz, so with pistons pushing down on compression and therefore aided by gravity, and with the intake air being sucked as well as pushed into the chambers, we benefit from higher octane fuel.

After about 10000kms of anal record keeping on different fuels in different bikes, 95 octane is just under 5% more efficient. That doesn't pay the cost differential, but it does suggest the bike is running better - and that's how it feels. In summer, both bikes ping on 91, and both run like crap on anything with ethanol in it. They run rich on 98 (our premium premium). And conversely to the US, both don't like Shell fuels, but prefer BP or Caltex.

For those who missed it:

the benefits are probably not in the higher octane rating, but in the quality and cleaning properties of a better fuel.

Also possibly that the premium fuels are claimed to be more dense??

Hey - if they ran better on 91 I'd save the money - I'm the original tight - ***! But they both now drink 95 Caltex or BP only and seem to appreciate it.

I don't know why - I just know it is!

[arsenic]

In Australia, you use a Research Octane Number (RON). RON is determined by running the fuel in a test engine with a variable compression ratio under controlled conditions, and comparing the results with those for mixtures of iso-octane and n-heptane. The US and Canada uses Pump Octane Number (PON). In the US and Canada, 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). It may also sometimes be called the Pump Octane Number (PON). It's called Wikipedia, there's more than porn on the internet you know. So, by using 95 in Australia, that is like using 91 in the US.

[TRPUT]

Thanks - I have more important things to do than search the www for porn and other BS not related to work or interests ... but it's nice to know why I'm right!

Seems our octane exchange rate is about the inverse of the dollar exchange rate at the moment!

[mstngsrule68]

i run 93

[Drinknthink]

Anyone can say what they want, but I know premium feels better in my bike then lower octane gas. It is an obvious difference. So say what you want. And my only mods are a jet kit, and exhaust.

[Kreylyn]

Anyone can say what they want, but I know premium feels better in my bike then lower octane gas. It is an obvious difference. So say what you want. And my only mods are a jet kit, and exhaust.

This clearly points out that your jetkit is not tuned properly, and your running lean.

That's what higher octane fuels do for you... retard the detonation of the fuel mix... if the fuel mix is lean, it's detonating too early. It's why lean gives more kick, but also makes things less smooth when it's running.

If higher octane reduces the vibes... richen your mixture so the bike is running correctly on the proper fuel.

krey

[hardlydangerous]

This clearly points out that your jetkit is not tuned properly, and your running lean.

That's what higher octane fuels do for you... retard the detonation of the fuel mix... if the fuel mix is lean, it's detonating too early. It's why lean gives more kick, but also makes things less smooth when it's running.

If higher octane reduces the vibes... richen your mixture so the bike is running correctly on the proper fuel.

krey

yep
your right on the money.

[loudnlow7484]

This clearly points out that your jetkit is not tuned properly, and your running lean.

That's what higher octane fuels do for you... retard the detonation of the fuel mix... if the fuel mix is lean, it's detonating too early. It's why lean gives more kick, but also makes things less smooth when it's running.

If higher octane reduces the vibes... richen your mixture so the bike is running correctly on the proper fuel.

krey

That's pretty much the bottom f'n line here.......... No stock GSX-F generates enough cylinder pressure to justify using anything other than regular grade fuel. If you have issues on regular, then you have issues with your bike.

FWIW- I usually ran premium, because I knew my jetting was a little off. I'm still working on getting my flatslides set up, but I shouldn't have to use premium anymore if I get them dialed in. I've been contemplating setting it up for E85 instead, though.......