octane question
Elite HDF Member
Joined: Jun 2008
Posts: 4,109
Likes: 9
From: Connecticut
I use 91-93......because the manual says 91 min. but I have a freind that races cars and he can't understand why the min octane is so high. The compression ration of the 96 cu in displacement engine is 9.2-1 which isn't really that high. Anyone know why HD requires 91 min.....is it for a longer burn?
Extreme HDF Member
Joined: Aug 2007
Posts: 17,625
Likes: 1,665
From: Blairsville GA
My Pan likes premium leaded fuel. It doesn't get it.
My experience with the new bikes is use the cheapest thing that doesn't make the engine ping. MOst of the time 89 octane. On trips out west I have to get the premium gas and it still runs poorly and gets terrible mileage.
My experience with the new bikes is use the cheapest thing that doesn't make the engine ping. MOst of the time 89 octane. On trips out west I have to get the premium gas and it still runs poorly and gets terrible mileage.
Tourer
Joined: Oct 2009
Posts: 325
Likes: 1
From: missouri
ok the consensus here is 91 or higher octane... so the question becomes WHY? have you folks used 87 or 89 octane and had issues with it? pinging? power loss? or just read it ? wondering if there is objective evidence that high octane helps in the average bike?
Tourer
Joined: Jun 2007
Posts: 362
Likes: 1
From: Texas
In my piped, ac, tuned bike and car I run 93, as we have the option of 87, 89, or 93.
I also use Shell most times for a few reasons; Local gas station is Shell, I have Shell card and save 5 cent a gallon (when I use 40 gal a month), and they have seperate pumps for 93, so I do not have to worry about how much 87 gas I might be pumping in my tank. All gas in my area is 10% ethanol. Lawn more runs like crap on it.
I also use Shell most times for a few reasons; Local gas station is Shell, I have Shell card and save 5 cent a gallon (when I use 40 gal a month), and they have seperate pumps for 93, so I do not have to worry about how much 87 gas I might be pumping in my tank. All gas in my area is 10% ethanol. Lawn more runs like crap on it.
Road Master
Joined: Apr 2008
Posts: 994
Likes: 12
From: Alberta
In my piped, ac, tuned bike and car I run 93, as we have the option of 87, 89, or 93.
I also use Shell, Local gas station is Shell, and they have seperate pumps for 93, so I do not have to worry about how much 87 gas I might be pumping in my tank. All gas in my area is 10% ethanol.
I also use Shell, Local gas station is Shell, and they have seperate pumps for 93, so I do not have to worry about how much 87 gas I might be pumping in my tank. All gas in my area is 10% ethanol.
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Road Master
Joined: Feb 2011
Posts: 1,120
Likes: 4
I looked on the web for info about octane and this is what the Minnesota Department of Commerce says about octane:
1) High octane gasoline burns slower than low octane gasoline. The slow burn prevents engine knock when cylinder pressures are high.
2) If your engine runs well and does not knock or ping on low octane gasoline, there is no advantage in switching to higher octane gasoline.
3) If your engine knocks or pings, it does not necessarily mean something is wrong with the gasoline. It could be a problem with the engine’s electronic control systems, ignition timing or exhaust gas recirculation. On a high mileage engine, a carbon build-up in the cylinders can increase cylinder pressures and cause knock.
Some companies also mix 87 and 91 to get their mid grade........if they mix at the gas station where you buy.......the guy in the truck is calculating the mix. I'm not sure I would buy mid grade ever. Bottom line for me is if it's not pinging your ok.
1) High octane gasoline burns slower than low octane gasoline. The slow burn prevents engine knock when cylinder pressures are high.
2) If your engine runs well and does not knock or ping on low octane gasoline, there is no advantage in switching to higher octane gasoline.
3) If your engine knocks or pings, it does not necessarily mean something is wrong with the gasoline. It could be a problem with the engine’s electronic control systems, ignition timing or exhaust gas recirculation. On a high mileage engine, a carbon build-up in the cylinders can increase cylinder pressures and cause knock.
Some companies also mix 87 and 91 to get their mid grade........if they mix at the gas station where you buy.......the guy in the truck is calculating the mix. I'm not sure I would buy mid grade ever. Bottom line for me is if it's not pinging your ok.
Road Warrior
Joined: Jun 2010
Posts: 1,337
Likes: 4
From: Sunny South Florida
My bike runs best on 93 so that is what I feed it. Simple. 
This does not take into account knock sensors and motors that have a knock retard built into the ECM. You can do serious damage to a motor even if you never "hear" a knock.
I looked on the web for info about octane and this is what the Minnesota Department of Commerce says about octane:
1) High octane gasoline burns slower than low octane gasoline. The slow burn prevents engine knock when cylinder pressures are high.
2) If your engine runs well and does not knock or ping on low octane gasoline, there is no advantage in switching to higher octane gasoline.
3) If your engine knocks or pings, it does not necessarily mean something is wrong with the gasoline. It could be a problem with the engine’s electronic control systems, ignition timing or exhaust gas recirculation. On a high mileage engine, a carbon build-up in the cylinders can increase cylinder pressures and cause knock.
Some companies also mix 87 and 91 to get their mid grade........if they mix at the gas station where you buy.......the guy in the truck is calculating the mix. I'm not sure I would buy mid grade ever. Bottom line for me is if it's not pinging your ok.
1) High octane gasoline burns slower than low octane gasoline. The slow burn prevents engine knock when cylinder pressures are high.
2) If your engine runs well and does not knock or ping on low octane gasoline, there is no advantage in switching to higher octane gasoline.
3) If your engine knocks or pings, it does not necessarily mean something is wrong with the gasoline. It could be a problem with the engine’s electronic control systems, ignition timing or exhaust gas recirculation. On a high mileage engine, a carbon build-up in the cylinders can increase cylinder pressures and cause knock.
Some companies also mix 87 and 91 to get their mid grade........if they mix at the gas station where you buy.......the guy in the truck is calculating the mix. I'm not sure I would buy mid grade ever. Bottom line for me is if it's not pinging your ok.