High Altitude - Lower Octane Gas?
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Tourer
Joined: Jan 2010
Posts: 485
Likes: 2
From: Colorado
High Altitude - Lower Octane Gas?
I'm originally from California where 87 octane is the lowest octane gas you really see at gas stations. Common octanes available were 87/89/91. The 1st time I traveled to a higher altitude state, I saw 85 octane gas for the first time. I'm in Colorado (5500 ft) and normally run 85 in my Chevy trailblazer without issue.
I've always run 91 octane in my motorcycles, regardless of where I was, but my question is.....does anyone living in a higher altitude state regularly run 89 octane gas in their Harley without pinging? I'm tempted to try a gallon or two on an empty tank and see what happens, but wanted some 1st hand opinions first.
I've always run 91 octane in my motorcycles, regardless of where I was, but my question is.....does anyone living in a higher altitude state regularly run 89 octane gas in their Harley without pinging? I'm tempted to try a gallon or two on an empty tank and see what happens, but wanted some 1st hand opinions first.
Extreme HDF Member
Joined: Dec 2007
Posts: 13,402
Likes: 941
From: Illinois
I run my 010 Ultra at sea level with no pinging on 89 on my trip to the Keys last summer. That is all that I use. I have helped by installing an oil cooler and a Cobra Fi2000r fuel programmer. I run three bikes with the TC96 motor and they all use 89 octane. The air temperature was 100 to 105 for the entire trip.
When I go to over 6,000 feet, I use 85 octane which helps the bike to run better.
HD recommends 91 which is different from requires 91. Why? The Federal government "requires" that engines be able to run on 87 octane. They are even in the process of requiring airplanes to run 87.
When you run lower octane just shift at a higher rpm and do not lug the motor. Pinging is more in the control of the operator than the ECM.
I have run 85 octane in the mountains with a Buell Ulysses with high compression without any issue going through the Canadian Rockies.
The lower the gear the less likely pinging occurs. Twist the throttle in 6th gear going 60 yes you will have a problem. But a knowledgeable rider would not do that.
I run 89 in my Corvettes and Viper without issue also.
When I go to over 6,000 feet, I use 85 octane which helps the bike to run better.
HD recommends 91 which is different from requires 91. Why? The Federal government "requires" that engines be able to run on 87 octane. They are even in the process of requiring airplanes to run 87.
When you run lower octane just shift at a higher rpm and do not lug the motor. Pinging is more in the control of the operator than the ECM.
I have run 85 octane in the mountains with a Buell Ulysses with high compression without any issue going through the Canadian Rockies.
The lower the gear the less likely pinging occurs. Twist the throttle in 6th gear going 60 yes you will have a problem. But a knowledgeable rider would not do that.
I run 89 in my Corvettes and Viper without issue also.
Last edited by lh4x4; Mar 1, 2011 at 12:34 AM.
Ultimate HDF Member
Joined: Jun 2009
Posts: 6,932
Likes: 4
From: 46th State, USA
When I rode to Colorado in 2005 on my '03 Ultra Classic I used 91-93 octane fuel until I got to Colorado where 85 was all I could find in Colorado Springs. The bike seem to run fine until I got to Denver where it it didn't want to stay running at idle speed at stops. It also didn't seem to have the power at the higher altitude.
Road Warrior
Joined: Aug 2010
Posts: 1,268
Likes: 8
From: Detroit, the asshole of America
When I rode to Colorado in 2005 on my '03 Ultra Classic I used 91-93 octane fuel until I got to Colorado where 85 was all I could find in Colorado Springs. The bike seem to run fine until I got to Denver where it it didn't want to stay running at idle speed at stops. It also didn't seem to have the power at the higher altitude.
You can get away with lower octanes at altitude because of the lower cylinder pressure. I wouldn't be too afraid of backing it down one octane grade, but I'd also log data with a calibration tool to be safe.
Seasoned HDF Member
Joined: Oct 2006
Posts: 5,977
Likes: 85
From: Nevada
I'm originally from California where 87 octane is the lowest octane gas you really see at gas stations. Common octanes available were 87/89/91. The 1st time I traveled to a higher altitude state, I saw 85 octane gas for the first time. I'm in Colorado (5500 ft) and normally run 85 in my Chevy trailblazer without issue.
I've always run 91 octane in my motorcycles, regardless of where I was, but my question is.....does anyone living in a higher altitude state regularly run 89 octane gas in their Harley without pinging? I'm tempted to try a gallon or two on an empty tank and see what happens, but wanted some 1st hand opinions first.
I've always run 91 octane in my motorcycles, regardless of where I was, but my question is.....does anyone living in a higher altitude state regularly run 89 octane gas in their Harley without pinging? I'm tempted to try a gallon or two on an empty tank and see what happens, but wanted some 1st hand opinions first.
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Road Master
Joined: Nov 2009
Posts: 997
Likes: 3
From: Charlotte, N.C.
It can be done, the right way to do it is to tune the ECM. If you want to run lower octane you must cool the bike down (oil cooler fans and such), then you need to take a few degrees of timing out of the ignition. You will get less power and use a little more fuel, but a stock HD should not be run on lower octane with the exception of higher elevations not only do you loose oxygen which allows for a cooler burn you loose atmospheric pressure and this lowers you compression a little bit.
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