Fuel Octane

[cardinal93]

I've definitely found the octane ratings to be very different in different countries, but not performance in the beast. For instance, there are no options below 90 (at least that I've found here in Germany). That said I grab the closest nozzle (provided it's not diesel) fill 'er up and ride on! (My oil's still clean )

 

[Boog]

Hey Boog, I may have missed it but what did you find on the problem you were having after fill ups?

Jim, so far it has not happened after four fillups using the 87 octane fuel and NOT filling it to the brim; just to the borrom of the wire retention bar. Also, it has not been as hot on the days that I had the problem..

 

[tdragger]

I've definitely found the octane ratings to be very different in different countries, but not performance in the beast. For instance, there are no options below 90 (at least that I've found here in Germany). That said I grab the closest nozzle (provided it's not diesel) fill 'er up and ride on! (My oil's still clean )

Good sir, the sub-90 numbers listed by State-side captains refers to the method that octane is calculated in the USA and Canada. We use the (R+M)/2 method, also known as PON or AKI. Typically, the numbers are 3-4 below the measurement method that the rest of the world uses, RON.

So, "regular" gas for most of the world is 91 RON which would equate to 87 PON in the USA.

 

[Neville Lush]

In Oz we have 91 95 and 98. Then some brands have 100 which has ethanol in it. The 91 fuel we get here is, in my opinion, crap fuel. I am sure a stock bike runs ok on it, but thats because they are set up real lean etc . The biggest issue to me is the deposits left behind in the motor when using 91. I guess if one was constantly doing long trips, it would be less of a problem. I pull engines apart almost daily from one make or another and I can always tell the ones running on the 91. I had a rocket apart at 3000kms only and the inlet valves have about .020" of black carbon on them already. Have the top off a 11000km Harley at the moment and there is at least .030" carbon on top of the piston. If I pull apart the same sort of engine which has been on BP98 for example, I can wipe the piston clean with a rag moistened with fuel. Some earlier bikes with carbs will be very reluctant to start, drain out the 91 and put in 98 and hey presto, it goes. Thats what I have found here at least. Cheers Nev

 

[Scuba Craig]

In Oz we have 91 95 and 98. Then some brands have 100 which has ethanol in it. The 91 fuel we get here is, in my opinion, crap fuel. I am sure a stock bike runs ok on it, but thats because they are set up real lean etc . The biggest issue to me is the deposits left behind in the motor when using 91. I guess if one was constantly doing long trips, it would be less of a problem. I pull engines apart almost daily from one make or another and I can always tell the ones running on the 91. I had a rocket apart at 3000kms only and the inlet valves have about .020" of black carbon on them already. Have the top off a 11000km Harley at the moment and there is at least .030" carbon on top of the piston. If I pull apart the same sort of engine which has been on BP98 for example, I can wipe the piston clean with a rag moistened with fuel. Some earlier bikes with carbs will be very reluctant to start, drain out the 91 and put in 98 and hey presto, it goes. Thats what I have found here at least. Chees Nev

Great write-up Nev. Most of the octane-related discussions I have read to-date focus on performance. Its useful to read some other factors related to octane choice.

 

[TRIIICK]

Octane 101.. I've had some problems with my bikes using 87 octane the lowest grade here in the states. I was getting a noticeable pinging sound especially in the v-twin. I moved up to 89 octane and it was better but still a noticeable difference in how the engine was running. Then it wasn't till i realized i live at sea level where the air is a lot more denser than that of higher altitudes. I switched to 93 octane it has been runing smooth no pings no knocks. High octane can be a crap shoot too most gas stations run out of 87 octane and if your already at the pumps most will bite the bullet and use 89 octane. You never really know how long the 93 has been standing in the tank in this economy. JM2C.

 

[cr0ft]

Around here in Scandinavia we basically get (using the RON system) 95 and 98, but they're both polluted with Ethanol. I'd use the 95, but that's 10% Ethanol and the 98 is 5%. So I use the higher and have had no issues except that the cost gets ridiculous up here. I'm basically avoiding as much of the Ethanol as I can as that stuff is just not good for any engine, and to add insult to injury it's not even more ecological - producing, storing and transporting all those oceans of Ethanol makes up for the slightly lowered emissions from vehicles. But the corn manufacturers selling it for biofuel are happy taking the subsidies... crap science annoys me, especially when all cars around here need to swallow all that alcohol for no good reason.