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Old 10-06-2013, 08:09 PM   #31
SOP Dirt-Rider
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Just what is the purpose of higher octane? To prevent premature ignition. The tighter the squeeze, the higher the octane. We do not want ignition to happen before the compression stroke is complete, one way to control this would be to adjust the valve timing, decreasing compression. This would require a differant cam. Another method would be to delay when the fuel is injected, but that would be finicky at best. Both would result in a loss of performance as it is circumnavigating the benefits of higher compression.
Another option, and no, I am not slamming the F8GS, would be to buy a bike that doesn't require the higher octane. Performance comes at a cost, not always in a dollars and cents manner.
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Old 10-06-2013, 08:50 PM   #32
AK650
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Quote:
Originally Posted by SOP Dirt-Rider View Post
Just what is the purpose of higher octane? To prevent premature ignition. The tighter the squeeze, the higher the octane. We do not want ignition to happen before the compression stroke is complete, one way to control this would be to adjust the valve timing, decreasing compression. This would require a differant cam. Another method would be to delay when the fuel is injected, but that would be finicky at best. Both would result in a loss of performance as it is circumnavigating the benefits of higher compression.
Another option, and no, I am not slamming the F8GS, would be to buy a bike that doesn't require the higher octane. Performance comes at a cost, not always in a dollars and cents manner.
In our emissions conscious environment, getting performance via high compression is a fact of life, unless you do it via large displacement, which is counterproductive, if you want a lighter, off road bike.

I suspect the BMW low octane remap, primarily just pulls timing, just as the ECM in a bike with spark knock detect does. While it would almost have to degrade performance to some degree, I doubt it's anything earth shaking.

Jeff
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Old 10-06-2013, 09:05 PM   #33
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I've considered switching mine back, but in reality I just don't see the point. If there's a performance loss it's not in the RPM range I typically run around at...
Thank you.
That is the EXACT type of data-point I am looking for.
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Old 10-08-2013, 04:02 AM   #34
BlueRidgeKat
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Interesting thread. My wife has a F800ST which like the GS calls for supreme fuel. We have a Marathon station near home that has regular 87 octane, supreme 93 octane and a mid grade ethanol free 90 octane. I would like to use this ethanol free fuel. You guys are the experts.... is the 90 octane close enough to supreme? We tried a tank and she couldn't tell any difference but not sure if we should use it all the time.
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Old 10-08-2013, 06:32 AM   #35
FredRydr
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Originally Posted by WoodWorks View Post
I often ride in the Great Basin area (eastern OR, northern NV, ID, UT) where most gas stations don't carry premium. There are plenty of places out here where you can ride all day and not come across a premium dispenser.
Since your engine doesn't need premium in that high elevation region, why not just add higher octane available from gas stations at lower elevation when you drop in elevation?

Fred
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Old 10-08-2013, 10:28 AM   #36
jttele
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Quote:
Originally Posted by BlueRidgeKat View Post
Interesting thread. My wife has a F800ST which like the GS calls for supreme fuel. We have a Marathon station near home that has regular 87 octane, supreme 93 octane and a mid grade ethanol free 90 octane. I would like to use this ethanol free fuel. You guys are the experts.... is the 90 octane close enough to supreme? We tried a tank and she couldn't tell any difference but not sure if we should use it all the time.
If it's the same recommendation as the GS, then yes, the 90 octane is fine. BMW calls for 89 octane in the GS. The Ethanol free in the 90 octane is just another benefit for you. I sure wish I had a station in my area with Ethanol free! That crap is complete bulls*** it, besides the loss of mileage with it, it almost got me killed when it caused the fiberglass tank on my Cagiva to melt and the resultant goo to stick my carb slide wide open.
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Old 10-17-2013, 07:40 PM   #37
JRose
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Put 87 in my '13 this past week, no I'll affects.
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Old 10-18-2013, 07:25 AM   #38
CheckerdD
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I considered remapping my 2010 800 before going to South America in 2012. But I did not do it and gas in places like Mexico or Argentina is better than gas you can get in the US because it aint diluted with ethanol. Bike runs smoother with a slight but noticeable increase in power on 100% gas than our 90%. Exxon, BP and Shell don't forget how to refine gas just because they are doing it in a third world country. Poor third world gas is a common misconception. I am doing Russia next summer. Everyone I talk to says it's 93 octane the whole way. So my vote is against remapping. Dave
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Old 10-18-2013, 08:26 AM   #39
lakota
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Just remember that 93 octane in Europe is not the same as 93 octane in US/Canada
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Old 10-18-2013, 08:51 AM   #40
RexBuck
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When I did my trip around Mexico a couple of years ago there was a couple of occaisions when I couldn't find premium. Bike ran fine but I did notice a bit of pinging when it pulled hard.

Had it mapped for Regular before my South America trip and I would estimate that I lost a small amount of gas mileage . . . maybe 1 or 2 mpg. No pinging problems with lower octanes though.

I still use premium when I can but regular works just fine on occaision. Actually, finding gas without ethanol is a bigger plus for me.
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Old 10-18-2013, 10:03 AM   #41
Full Power
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Rexbuck: Since returning from your trip SOUTH, have yopu re-mapped your ecm to it's original 89 octane setting ?
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