What type of gas...

Back in the day, our current highest octane was the lowest. And there was none of this ethanol shit. If you can find a station with ethanol free and the highest octane is your best choice.
 
I've wondered this too, I usually just use regular, should I be running premium? It gets such good MPG another 20 cents a gallon doesn't really bother me. Whats that, another $60 cents per 120 miles or so?
 
I cant seem to find any ethanol-free fuel here in South Bend, IN... wonder if it has anything to do with the Ethanol Plant about 1.5 miles from my front door?

I have been reading a few things that say that Ethanol actually does not agree with 30+ year old fuel systems. especially floats and tanks
 
I'll be the black sheep here & say that ethanol is really good gas, however, to get its full potential the engine needs to be rid of lower grade components & the compression should be higher. All rather expensive; wiki has a good spread about it.

As a general rule of thumb, I use 87 octane for lower compression engines, 8 1/2:1; 89 for up to 9-9 1/2-10:1; & higher for 10 1/2:1 up. So, mostly I use 89 octane (regular unleaded, without ethanol), seems to work just fine; no engine knock or pinging--yet--10 or so years now.
 
Thanks all, Belle....what compression is the 81 xs650 SH...do you know? I'm in Columbus, OH...looks like there are no Ethanol free stations near me...
 
Wonderful! Clear as mud! :)

I guess it comes down to how each bike performs. Mine tends to be pretty temperamental when even getting down to a 1/4 of a tank...other than that, it's good on 87...just wondering.
 
Stay away from ethanol if you can, but that is way easier said than done. 4 strokes can tolerate ethanol better than a 2 stroke. If you ride a lot you will have less problems with ethanol than a guy that rides only once in a while. Ethanol can start phase seperation in 30 days. Buy your ethanol from a very busy station to get the freshest fuel possible, even if you have to spend a few penny's more per gallon.
 
Patches said:
Back in the day, our current highest octane was the lowest.
Click to expand...

Because of this, the bike gets good enough mileage I feed her the best I can find. Exclusively 93, was able to get non-ethanol up until about 6 months ago. Considering I use less than 6 gallons a month in the bike (will go up if I decided to start commuting on it) I would buy higher octane/ethanol free if I could find it locally.

~ Derek
 
usually use bikez.com as a reference on stock'er stats--

the '81 by bikez said 8.4:1

Need to look at your engine also...if engine is hot rod but lower compression category (not always bad), might run a higher octane & get better results than lower...
 
Also, E85 is 85% gas & 15% ethanol--it can be bad for your engine & parts--you should learn about it; we, as a society, are likely to end up there...somewhere...anyway


But think about it like this, old dudes used to run moonshine (straight ethanol), but they sometimes blew up their engines because it ran so hot--but the parts were inferior--that's why regular (leaded) gasoline was used, lower combustion, higher lubricant to keep the parts working longer (so on, so on, pretty much that &, well, that...so to speak)
 
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I was running 87 for the first week or so, but the bike stalled and popped alot, and kinda seemed sputtery in 1st gear, I threw some fuel system cleaner and a tank of 92 in and it has smoothed out alot. Im just gonna stick with 92. As little gas as I use, the extra few cents really isnt a big deal.
 
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hi guys,,, well i use 98% unleaded,,, my bikes run clean with it as well as my falcon ... even both my big bob mowers run well ,, i,ll stick with it ,my local tiny town servo/eat in stop is in the process of installing a new pump for 98% .. they are doing away with 95$ and just having 91/98 regards oldbiker
 
Compression ratio is only half the story, the other is heat. When you compress gas it heats up. If it gets too hot it burns before you want it to. That government page assumes you're running a computer controlled, liquid cooled car, not a 40 year old air cooled engine with primitive combustion chamber and funky mechanical timing. If you have either high compression or hot engine parts you may need higher octane. Your bike will tell you what it needs.
 
GreasyC said:
Compression ratio is only half the story, the other is heat. When you compress gas it heats up. If it gets too hot it burns before you want it to. That government page assumes you're running a computer controlled, liquid cooled car, not a 40 year old air cooled engine with primitive combustion chamber and funky mechanical timing. If you have either high compression or hot engine parts you may need higher octane. Your bike will tell you what it needs.
Click to expand...

So no one has mentioned the fact that the valve seats on these xs650 heads are quite soft and could stand the addition of a lead substitute (which would also increase octane). If you've ever lapped the valves on one of these heads you see how quickly the pitting grinds out of the seat. Nice for a quick valve job, but I'd rather have a nice hard replacement seat to stand up to the unleaded fuels we use now.

Oh, 87 with octane boost for the lubrication.

-=PO
 

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