Fuel Grade's

i have mostly run 87 in my seca 750 but decided to try 91 the other day after i found a sticker saying it calls for 91 leaded. and obviously everything is unleaded so would it run better with the additive.

 

I use the highest octane that does not contain ethanol. my 82 calls for 91 octane. haven't used lead substitute but after reading this and seeing that my bike is required to use 91octane LEADED GAS I will.

http://www.articlesbase.com/automotive- ... 68737.html

http://www.motorcycle.com/how-to/wrench ... -3417.html

 

There's been a few threads on this one, but here's the short version:
1 - You DO NOT need leaded fuel - the manual lies, our bikes are designed for unleaded;
2 - 87 is perfectly fine unless you've got a turbo, or are getting 'pinging'.

 

I have an 82' XJ650 RJ that i ran on 91 octane, then when riding out in the countryside i had to fill with 98, and to my surprise it ran better, quieter, and i get more km's per tank.

i'm not sure what northern hemisphere bikes are tuned to use, but 98 octane is great!

cheers

 

98 octane?

Where do you live so that you can find that stuff?

93 is the best we have around here. Hard to find fuel without ethanol added too.

In the '70s, we use to fill our CR250 Elsinore dirt bikes with aviation fuel and mix it with MC1 2 stroke oil.
I can't remeber, but I think that was 110 octane.
Can't buy aviation fuel anymore.

 

A couple of years back when working as an airport manager I had ready access to 100 octane AvGas. I would run it my 650 periodically with no problems. It certainly made a huge difference in my lawnmower.

The nice thing about AvGas and the gasoline of years back is that it was pure gasoline. This ethanol crap is highly destructive of fuel systems and goes bad much quicker than gasoline. The FAA refuses to permit any fuel with ethanol to be used in any certified aircraft.... that should tell you something.

 

I read up on this recently because I was curious about why the motorcycles specify higher octane fuel than the compression might indicate.

There are two methods of measuring octane - Research Octane Number (RON) and Motor Octane Number (MON). Most of the world posts the Research Octane Number on their pumps. The specified octane rating in the XJ documentation is also RON.

In the US and Canada the number posted on the pump is the average of the two methods, often indicated on the pump as (R+M)/2.

According to info I found the RON of a fuel is generally about 5 points higher than the (R+M)/2 rating. So, USA 87 fuel is closer to 92 by world standards. In other words, in the USA 87 octane is fine in most circumstances.

WIKIPEDIA article for those interested.

 

I feel very fortunate in that there are 5 gas stations around here that have ethanol free gas and that's all I use. My wife was using e10 gas for a while but I convinced her to switch and she's getting about 15% better gas mileage. If gumming up the works isn't reason enough to stay away from ethanol, the decreased mpg should be!

mikeg

 

I've used nothing but 93 in mine since I got my 81 SECA. It seemed to help her run soother. We have one gas station that carries 112! I was considering?

SECA 750

 

I run premium just because so I have no rational argument to further the issue; although back in the early '80s when I had my SR500s, you could still buy 106 octane racing fuel at the pump in my area, and the SRs LOVED it.

 

I believe that the higher octane rating gives the fuel a slower burn. Lower octane explodes under heat and compression. So higher octane would have cooler combustion temps. Thus a cooler running engine which in our case helps alot.

 

I run premium (which is 91 around here), since it give me more leeway in playing around with ignition advance.

 

Actually, higher octane is harder to burn. Hence wanting to run 92 or 100+ on high compression engines, as it won't pre-ignite or cause detonation.

 

Think thats what I just said..............Harder---- slower same thing

 

Not at all. Once higher octane ignites, it produces the same energy (give or take a small enough amount it doesn't matter for normal applications) that lower octane does. But if you put lower octane in that same situation, the compression could ignite it, or if your head temps are high enough, the heat transfer alone can cause pre-ignition.

Harder to burn is not the same as slower burning. Very different, in fact.

 

Also, I want your fuel injection setup. Awesome.

 

Switch263 is right. Octane rating is not a measure of the energy content of the fuel. You'd see a tiny difference in the amount of energy per volume of premium vs regular, but the main reason to have different grades of fuel is that you can have ignition due to compression if there are lighter hydrocarbons in the fuel. This is circumvented by having a larger fraction of octane in the more expensive fuels. Most of the time, more expensive fuel is a waste of money.

 

despite the differing opinions concerning the pro's and con's of using high octane fuel,
I have to say I have not had a bad experience using either 95, 96 +10% ethanol, or 98. It has been my experience that not only does the engine run better but fuel consumption is markedly improved. In these ways I feel the extra cost is worth it, the bike does not rev as much to achieve the same speed.

cheers

 

All pump gas in New York has atleast 10% ethenol. :evil:

 

Race fuel is available 20 miles from me... wonder if they'll deliver.
hah.

Nah, I always use premium in all my small engines.
My car sticks with regular.

But the ATV, the boat, the bike... that's premium!

 

Octane isn't a measure of energy content. It is a measure of the inability to combust.

The higher the octane, the less likely it is to combust. Which is good for higher compression engines.

The problem with using higher octane is that it causes the engine to run hotter.

This is why it is not recommended for most small engines. There is usually not enough air flow to prevent the engine from over heating.

The recommendation on this forum has always been to use the lowest octane to get the results you need. If possible, stay away from ethanol, but, if you can't live with it.

If you feel that running premium gives you better results, than by all means, run premium.

Otherwise, run regular.

 

higher octane = higher temps? i was unaware.