Best octane gas?

[Six-Five-O]

The placard on my '81/H says "Reasearch Octane 91 min", which translates to 87 octane at the pump.

And so it goes......So are you saying that our 87 octane regular is the correct grade of gasoling to use in our XS engines?

[pamcopete]

Six-Five-O

Well, to be more precise, 87 Octane at the pump is the minimum octane, and you should adjust according to conditions. I used 89 octane in my faithful '78/E for 12 years after determining that it performed better and gave me better gas mileage than 93 octane.

Note: I added the word minimum to the original post.

[Six-Five-O]

Great thread guys. ;D

[Fry]

Hey Pamcopete does the 89 octane over there in South Carolina have 10% ethanol in it like we have up here in Iowa. I've heard all kinds of "experts" say it will eat my carbs rubber parts but if you've been doing it for 12years I'm gana start using it, it's 10cents cheaper than 87 up here in the midwest.

[Burns]

Pamcopete really said it all with this part of his quote:

"If the vehicle knocks on the recommended grade, a higher octane grade should be selected"

Which, to repeat my mantra, means, in the real world, run the lowest octane you can THAT DOES NOT KNOCK.

[squrl78]

I found the emissions tag on my 82 and it said 91 octane min. any other questions about the tag just ask.

[tomterrific]

The problem with trying to get away with the lowest octane (87) is that 99% of the time it is maybe just fine, It's that 1% that detonates a hole in your pistons.

Fast freeway on a hot day, the road turns into the wind and you turn up the throttle to keep up with traffic. The wind noise is loud. Is that a valve ticking or my imagination? Poof! Where did all my power go? Now the list gets the post. My bike lost power on the freeway and now only runs on one cylinder. The engine smokes. What is the problem?

I keep it simple and run 92 or 93 octane in all my bikes.

Tom Graham

[pamcopete]

squrl78

To determine your vehicle's octane requirement, look at the manufacturer's recommendation in your owner's manual. Most auto manufacturers recommend 87 octane gasoline, as measured by the (R + M) / 2 method on a test engine under defined operating conditions. If the vehicle knocks on the recommended grade, a higher octane grade should be selected.

Some foreign vehicle manuals recommend a Research Octane Number (RON) instead of the more common octane rating that appears on most gasoline pumps. As a rule, the recommended octane rating can be determined by subtracting four (4) from the recommended RON number. A vehicle that calls for "91 RON" could use 87 octane gasoline (as measured by the (R + M) / 2 method).

The placard on my '81/H says "Research Octane 91 min", which translates to 87 octane minimum at the pump.

The (R+M)/2 is the standard displayed on the pumps.

So, squrl78, check that emissions tag again and see if it mentions "91 RON" or " Research Octane 91 min." which would equate to 87 at the pump.

[nudude53]

I use the highest octane I can find at the pump, and then add about 2 ounces of "Seafoam" to the tank, it is a carb/injector cleaner with light oil in it that will keep your carbs clean and the upper end stay lubed up. The "Seafoam" is about $8 for a 16 oz. can, the hightest gas about 25 cents per gallon more than regular. The final outcome...... bike runs better, idles smoother, and starts easier. About $2 extra per tank full. Not bad compared to the cost of rebuilding the top end.

Spend a little now or alot later!

[midnrider]

high test...; and not the cheap brands they are 91 whereas the name brands are 93, hey 20 cents different per gas stop...well worth it

[maico996]

Anyone ever try running Av gas? I live right next to a little airport and have access to LL104. I've spoken to a few people who run Av gas in their vintage motocross bikes but have also heard that it's a bad idea in a race bike because of the stabilizing additives necessary for altitude and temperature. It's also formulated for the constant RPM of the airplane engine. It's not really designed for the constantly changing revs of a motocross bike. But for riding on the highway it might be ok and the added lead is a little extra lubricant...any thoughts?

Scott

[pops]

1. The lead is very corrosive and will rot your mufflers out quickly.

2. It's illegal to run avgas in cars and motorcycles. The gov't doesn't collect road taxes on it and takes a very dim view of dealers who provide it for such use.

pops

[pamcopete]

Well, this gas shortage has forced me to use 87 Octane (91 RON) in my 81/H. We all know that the 34's on that bike are lean to begin with, so you might expect some pinging with 87, but not so.....bike runs just fine on 87 Octane. Starts the same, idles smoothly and no noticeable difference in cruise.

I'll probably switch back to 89 Octane when it's available, but I definitely do not see any need for a higher octane.

[voodoorider]

That's what I use too Pamcopete. I actually ran some 93 octane and the bike ran like crap. I did some checking and found out that boyer supposedly used about 90, I think 95 RON for Advance curve in the micro digital units. Maybe I got bad gas, maybe that's what did it, who knows. I use 87 for now and 89 when it's available again. The 93 made my idle rev, also the exhaust sounded different.

[tomterrific]

As far as running poorly with high octane: WHAT? Now if the 93 had ethanol and the 87 did not and the engine was lean to begin with. The premium fuels most often have a greater quantity of detergent to keep the combustion chamber and the fuel system clean so maybe the carbs and tank are dirty.

My all stock '77D with stock jets, K&Ns and stock mufflers runs great on 93 octane from any station and I fill up everywhere. It should run a bit lean with the K&Ns (and does) but it is smooth and trouble free with any 92 or 93 octane from anywhere. I honestly don't mind the extra 20 cents.

Tom Graham