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There has been many posts on fuel octane,how they actually effect power production and gas mileage and factory recommendations in the manual,wether its actual fact or warranty liability protection BLAhBlaH Blah.
I have been familiar with all the pros and cons for many years of using different Octane fuels and additives so I did an experiment today on a one hour ride on fairly flat route.Before I start I have a PCV with Ignition adjust and have about 8 to 10 degrees more advance dialed in in the cruising RPM range of 2200 rpm to 3000 rpm in the under 40% throttle positions.I also realize that the average mileage reading is a little optimistic on the dash also,but can be used as a consitent guide in my test run.
I have been using 87 Octane fuel here for the last week or so ,so off I went .I set the speed at 120K (apprx 75 MPH)per hour and set the cruise,rpm was at 2700 rpm most of the way and watched as I hit 55 miles per gallon over a 30 minute staedy run.More often was at 53.X.
When I got to my destination I had about an 1/8th of a tank left and filled it right to the brim with 91 Octane .Started my return trip and got rollin on the freeway,reset the average fuel reading ,locked into 120 K per hour and was surprised to see that I never got above 48 miles to the gallon on the way back.Was mostly at 46.X most of the time.Now I did have a bit of a head wind coming back ,so it may of been about 5% less due to wind issues.I did re test on a short run with no wind issues when I got home and never got above 45 miles per gallon.
A couple other observations with 91 Octane,one being the motor vibration seemed to be more pronounced,like it was not really happy with the new fuel and also there was more exhaust popping on deceleration,proably due to the fact that a lot of unburned gas residue was being exhausted out.Did not have this issue on 87 fuel.Appeared to run slighty hotter on 91 Octane but it was only slightly higher.
I want to do another run on the freeway again ,with 91 Octane,to the same destination again so all things are even steven, and fill up and return on 87 Octane and see what happens.But it appears that my motor is happier on 87 Octane.
 

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I have been running mid-grade fuel since I completed the stage 1 upgrade to my bike last summer. It runs better and my mileage has improved to about 6.2 L/100 KM combined city and highway at 10% above legal speeds.

It might be best if our American friends understand that you are quoting MPG in Imperial Gallons, which are larger than US Gallons. Hence the upper 40's to low 50's MPG figures!

Terry...
 

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Discussion Starter #3
Yes you are correct,its referanced to a UK Gallon.Approx, 12% larger then a US gallon.
 

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There has been many posts on fuel octane,how they actually effect power production and gas mileage and factory recommendations in the manual,wether its actual fact or warranty liability protection BLAhBlaH Blah.
I have been familiar with all the pros and cons for many years of using different Octane fuels and additives so I did an experiment today on a one hour ride on fairly flat route.Before I start I have a PCV with Ignition adjust and have about 8 to 10 degrees more advance dialed in in the cruising RPM range of 2200 rpm to 3000 rpm in the under 40% throttle positions.I also realize that the average mileage reading is a little optimistic on the dash also,but can be used as a consitent guide in my test run.
I have been using 87 Octane fuel here for the last week or so ,so off I went .I set the speed at 120K (apprx 75 MPH)per hour and set the cruise,rpm was at 2700 rpm most of the way and watched as I hit 55 miles per gallon over a 30 minute staedy run.More often was at 53.X.
When I got to my destination I had about an 1/8th of a tank left and filled it right to the brim with 91 Octane .Started my return trip and got rollin on the freeway,reset the average fuel reading ,locked into 120 K per hour and was surprised to see that I never got above 48 miles to the gallon on the way back.Was mostly at 46.X most of the time.Now I did have a bit of a head wind coming back ,so it may of been about 5% less due to wind issues.I did re test on a short run with no wind issues when I got home and never got above 45 miles per gallon.
A couple other observations with 91 Octane,one being the motor vibration seemed to be more pronounced,like it was not really happy with the new fuel and also there was more exhaust popping on deceleration,proably due to the fact that a lot of unburned gas residue was being exhausted out.Did not have this issue on 87 fuel.Appeared to run slighty hotter on 91 Octane but it was only slightly higher.
I want to do another run on the freeway again ,with 91 Octane,to the same destination again so all things are even steven, and fill up and return on 87 Octane and see what happens.But it appears that my motor is happier on 87 Octane.
Here in Australia, we have 91 octane, which may also have ethanol 10% added, 95 octane & 98 octane, with some servos, selling 100 octane.
In my users manual, it states that I must use 95 & up, although I have used 91 without the Ethanol, with no probs.
 

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There has been many posts on fuel octane,how they actually effect power production and gas mileage and factory recommendations in the manual,wether its actual fact or warranty liability protection BLAhBlaH Blah.
I have been familiar with all the pros and cons for many years of using different Octane fuels and additives so I did an experiment today on a one hour ride on fairly flat route.Before I start I have a PCV with Ignition adjust and have about 8 to 10 degrees more advance dialed in in the cruising RPM range of 2200 rpm to 3000 rpm in the under 40% throttle positions.I also realize that the average mileage reading is a little optimistic on the dash also,but can be used as a consitent guide in my test run.
I have been using 87 Octane fuel here for the last week or so ,so off I went .I set the speed at 120K (apprx 75 MPH)per hour and set the cruise,rpm was at 2700 rpm most of the way and watched as I hit 55 miles per gallon over a 30 minute staedy run.More often was at 53.X.
When I got to my destination I had about an 1/8th of a tank left and filled it right to the brim with 91 Octane .Started my return trip and got rollin on the freeway,reset the average fuel reading ,locked into 120 K per hour and was surprised to see that I never got above 48 miles to the gallon on the way back.Was mostly at 46.X most of the time.Now I did have a bit of a head wind coming back ,so it may of been about 5% less due to wind issues.I did re test on a short run with no wind issues when I got home and never got above 45 miles per gallon.
A couple other observations with 91 Octane,one being the motor vibration seemed to be more pronounced,like it was not really happy with the new fuel and also there was more exhaust popping on deceleration,proably due to the fact that a lot of unburned gas residue was being exhausted out.Did not have this issue on 87 fuel.Appeared to run slighty hotter on 91 Octane but it was only slightly higher.
I want to do another run on the freeway again ,with 91 Octane,to the same destination again so all things are even steven, and fill up and return on 87 Octane and see what happens.But it appears that my motor is happier on 87 Octane.
To conduct an accurate study, it really needs to be more "long range". Start with a completely full tank of 87 octane, reset the trip meter and avg mpg. Run at least 5 full tanks of the same gas (brand and octane) without resetting the meters. Document the amount of fuel used and distance travelled on each tank, and calculate the mileage on each tank. On the 5th tank, get it as close to empty as possible before filling with 91 octane. Then reset the trip and avg mpg meters and do another 5 tanks. Then compare the numbers. 5 tanks of fuel should even out the variables of wind, speed, rpms, road incline and conditions. I know, it's a lot more time consuming and can't be accomplished in an hour. Science sucks, right? Some testing takes a damn decade!
 

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Here in Australia, we have 91 octane, which may also have ethanol 10% added, 95 octane & 98 octane, with some servos, selling 100 octane.
In my users manual, it states that I must use 95 & up, although I have used 91 without the Ethanol, with no probs.

Measured a little different. When we "yanks" refer to 87 octane, we're referring to a fuel that's equivalent to your 91 octane. Sort of like how an Imperial Gallon and US Gallon are different. Likewise 89 to 91R+M/2 (US Standard) is roughly equivalent to 95RON (elsewhere, 93=98, etc. etc.
 

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Discussion Starter #7
tstorey823 ,yes it would be more accurate doing it long range,but to have a 10% or better differance just with this one test shows me proably 87 Octane will give better mileage in all cases.My plan is to do it once more but with 91 Octane first and then return on 87 against the wind next time,with of course all measurements reset,using the same route.Running the same route pattern 5 times would be pretty boring after awhile.LOL
 

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Measured a little different. When we "yanks" refer to 87 octane, we're referring to a fuel that's equivalent to your 91 octane. Sort of like how an Imperial Gallon and US Gallon are different. Likewise 89 to 91R+M/2 (US Standard) is roughly equivalent to 95RON (elsewhere, 93=98, etc. etc.
Thanks Romans
 
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