Which octane gas?

Hey!

So when I was cleaning the side covers off my 83' 750 maxim, On the inside of one there is a sticker with some specifications and the like.

Under "Fuel Specs"

It says:

Gasoline Grade: Regular(Leaded)
Research Octane: 91 Min.

A few questions:

Obviously I'm not going to be able to put leaded gas in it as it was outlawed in the states in 1975. I'm not sure when it got outlawed in japan.

But anyway, which octane do you guys use?

As well as - most places around here have 10% ethanol in their lower grades, Is that bad for our bikes? Im pretty sure the 91 octane doesn't have ethanol where I live. well at least thats what they say, lol.

Thanks for the imput guys. 8)

 

In the U.S. we use a different system, Pump Octane.

91 Research Octane ~ 86 Pump Octane. In other words, regular.

If you can really get fuel without ethanol I'd go that route, but I seriously doubt if you can without going to an airport or marina.

 

No matter the octane? (for the ethanol free gas)


And thans for the Pump/REsearch difference, I tell ya, I learn something new everyday!

 

Octane requirements depend on engine compression and elevation. The higher your compression the higher the octane you need to keep the burn slow and steady like it should be. The higher up you go in elev. requires lower octane since atmospheric pressure has dropped and less O2 is available for combustion. It seems counter-intuitive but lower octane gas burns quicker and more easily than higher octane.

Somewhere on here we had a discussion about this a few months ago. This subject became an argument with a friend years ago and I spent too much time researching it to settle our disagreement.

As a general rule above 9:1 compression you need to use the premium stuff, and below that regular is good enough. But always you should go by how the gas works in your engine, many factors play in so what works best is what works best. Also modern engines (not our XJ's) can adjust timing and fuel on the fly and compensate for almost any octane rating used.

Ethanol is VERY BAD for carbs, and engines in general, especially when mixed with other gas additives like MTBE. I wouldn't trust the gas supplier and just use a stabilizer or ethanol remedy additive all the time (a little goes a long way though so don't put in too much).

 

I haven't had a problem running 87 Octane, 10% alcohol, 97* air temp, near sea level, and 100% humidity. (outside of sweating to death)

 

You can safely go up in octane, but if the engine doesn't require it you're wasting money.

If you're getting rid of the ethanol by going up in octane it might be worth it, especially this time of year when it spends a lot of time parked.

 

I made an error in my earlier post that I just corrected.

91 Research Octane is roughly 86 Pump Octane.

 

i go out to my local airport and buy 100 octane leaded fuel. they use it in planes. burns like cam 2 but cheaper and u notice the power.

 

Our engines have never needed leaded fuel - all XJ's have the hardened exhaust heads to handle unleaded fuel. Those stickers were only placed there so potential buyers in the US weren't scared off by perceived need for unleaded fuel in the early 80's.

Any regular fuel is fine, unless you've modified the engine for high compression; or your getting pre-ignition (pinging) from carbon buildup in the cylinders.

Unless your bike is a daily rider, and thus doesn't sit with fuel in it, avoid ethanol fuels whenever possible. Even if you have to go up in octane ratings to get it. Here in Canada, at least for the time being, buying the premium 91 octane at Shell stations means you're getting straight gas - no ethanol. So that's what I've been running all my small engines on for years - motorcycle, boat motors, gas trimmers, snow blower - the lot. The Ministry of Natural Resources does the same thing - even sent out a communication to all offices to use premium only in small engines.
If your not going through the fuel regularly - avoid ethanol at all costs!