Gasoline grade?

I know this is a subjcet based on opinions, but what is the best grade of oct to use for my 650?
I was thinking of just rotating from regular to mid every other fill, to try to keep it slightly higher then the standard 87. but not sure if there is a "official" standard that yamaha recommended.

 

You really need to learn to use the "Forum Search" feature.

This has been discussed at great lengths, repeatedly.

http://xjbikes.com/Forums/viewtopic/t=31994.html

http://xjbikes.com/Forums/viewtopic/t=28406.html

http://xjbikes.com/Forums/viewtopic/t=25631.html

http://xjbikes.com/Forums/viewtopic/t=18867.html

Just for starters. (I searched for "fuel octane")

 

yes i did do some reasearch on it prior, just seems every one i find has mixed reviews thats why i asked the simple question as to what was recommended.

Thanks for the info though.

 

By me its 20 cents different between 87 octane and the highest grade. So, I am not really concerned about wasting 40 cents every time I fill it up with premium. It was recommended to me by a bike mechanic and the bike runs good on it.

 

Yes i agree, being the higher octain does burn cleaner and also a lower temp too, which is why its easier on motors in the long run, less gunk, but like you said filling up 2 gallons, what is the extra .40 going to make a difference.

 

My bike seems to run OK on any grade.. I run a tank or two of high grade through a couple times a month for the hell of it but really I don't seem much performance difference.

 

long term i know it keeps the heads cleaner because they burn cleaner, may not be a "performance" , but i know it doesnt build up all the gunk in the motor.

 

If your stickers are on the inside of your side covers I believe it says 92octane. I always run the highest in between 91 and 93. Sometimes thats not always available so I have to run a lower octane. I dont notice much of a differnce either.

 

Actually mine says regular leaded gasoline. I have an 82 XJ650 Maxim. It is on the sticker that covers the TCI. That being said there is no way to tell if that cover is the original cover or not. 29 year old bike, and I am as best as I can tell the 4th owner but I could be the 5th.

 

I believe it's 91, and that's a Research Octane Number. In North America we use Pump Octane Number which has a lower value.

The 91 RON is roughly equivalent to 86 PON. In other words, in North America 86 or higher, 91 or higher in the rest of the world.

This has been hashed out in those threads too.

The octane number is a metric that indicates the tendency of the fuel to spontaneously ignite due to temperature and pressure (knock). Higher octane fuel requires a higher temperature/pressure to spontaneously ignite.

From Wikipedia:

Octane rating does not indicate the burn temperature. If it were appreciably different it could create carbon problems (low temp) or cooling problems (high temp).

Higher octane fuel does not have any additional cleaning (combustion chamber, valves, fuel system etc.) capabilities over lower octane fuel. If some blenders premium has these characteristics it's from the additive package, not from the gasoline. I suspect it's mostly marketing hype. I've never heard of anyone having an engine problem other than detonation caused by low octane fuel.

Blending ethanol is a cheap way to boost octane. If that's done you'll actually get poorer performance, mileage and power from the high octane fuel. BTW, ethanol is usually the major component in octane boosters.

In other words - if it isn't knocking going up in octane rating gets you nothing except a thinner wallet.

 

Hmm, there's a gas station down the street from me that sells 87, 93, and 100 octanes, $3.65, $5.18, $7.25 respectively Maybe one of these times when I'm running on empty I'll fill up with the 100 octane and see what difference it makes if any.

From what I understood though, lower octanes were like running leaner, higher octanes were like running richer with their effects to your engine. But really I have no idea, that's pretty much just a guess that I've been going on.

 

I run premieum 93 octane, its still alot cheaper than filling my truck!

 

There is one kicker that's been added to the infamous octane discussion.... ethanol.

Some manufacturers/stations vary the level of ethanol in their blends - eg. regular has 10%, mid-grade has 5%.

Here's the thing - SOME of them have ZERO ethanol in their premium blends (octane rating varies). As most of us know, ethanol is not so good for 30 year old motorcycle engines, and intakes/carburetors with rubber parts.

Thus, I've started running Shell Gold (91 octane) in my bike, even though I don't give a flying crap about the octane rating -- I'm paying the extra to get fuel without ethanol.