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From the Owner's Manual of my 2017 Australian market R9T.
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My 2016 BMW R9T owner's manual recommends unleaded premium. So I always fill up with non-ethanol premium.
 

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Actually there is absolutely no difference in available energy from a gallon of regular vs a gallon of premium. The energy released by their combustion is identical. The only difference is the temperature at which pre-ignition can occur and the speed of the wavefront in the cylinder head. If the engine is engineered to use premium, then you ought to use it. If it isn't, you gain nothing, despite all the old wives' tales we grew up with. It's more important to pay attention to the detergent package in the fuel you use. I posted a link to Top Tier gasoline suppliers above. Independent tests by the AAA showed that cheaper blends compromised fuel economy by 2 to 4% and also resulted in increased carbon deposits. Those deposits are the cause of pinging is most cases. Here's another article that discusses these issues. It also contains a reference to independent tests and information on how to find good gas....Regular vs. Premium Gas, Redux

http://www.aaa.com/AAA/common/AAR/files/Fuel-Quality-Full-Report.pdf
Yep, you’re right, it’s about how quickly the volatile content is oxidized. Regular low octane fuel goes POP and premium fuel (same amount) goes POOOOOOOOP. The octane level slows down the chemical burn and gains horse power. Much longer stroke with more pressure translates into more push on the piston thus more power to the ground. Only difference in most grades of gasoline is the volume of octane and alcohol per gallon. Christin if the only difference is the amount of octane and alcohol in both of those grades ..then that difference has to amounts to some of the volume, right? So if you took two samples of premium in different containers and in one you remove the appropriate amount of octane and or alcohol to turn the premium sample into regular. My 1st question would be, how much less volume would the regular gas sample be ? My second question would be ,...what do petroleum company’s use to fill that Regular sample can back up to one full gallon because that’s how they sell it, by the gallon. If you’ve removed part of the volume you have to replace it with something equal in volume...What ? They’re referred to as additives and amount to inert ingredients that don’t burn but whose volume is equivalent in weight to the octane and alcohol that was removed. So although they are equal in volume they contain different chemistry and burn differently, thus the power achieved by each one is also very different. You could probable get that boxer to run on kerosene and alcohol if the mix was right. But low octane gas is not equal to premium grades except in volume. When I bought gas as a kid in the 60’s from a company named Sunoco Oil they sold a premium grade who’s name was 260, ....Sunoco 260 ...and it was touted as very high octane and was racing fuel, because of the high volume of octane. It was even better than Avgas at the time but as pollution control was catching on it was deemed as dirty and they started dumbing it down so now it’s sold as 100 octane. Still sold as racing fuel. Much of the levels of octane relate to levels of pollution as well as the level of power. Aviation gasoline is just like auto gas but it contains an octane called tetraethyllead because is enhances the length of burn and gives a higher power output for gasoline aircraft, but the emissions won’t pass when used in an automobile or motos. I’m not a petrochemical engineer but the major differences in gasoline’s is level of octane, lots of subtitle differences, enhancers and additives but The primary difference is in how much octane ... Pretty sure. Blitz
 

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Don’t know whether any truth in this, but, I’ve been told that the Premium Unleaded that Supermarkets sell is inferior to similar Premium Unleaded from the likes of Esso and Shell etc.
Ken.
 

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Yep, you’re right, it’s about how quickly the volatile content is oxidized. Regular low octane fuel goes POP and premium fuel (same amount) goes POOOOOOOOP. The octane level slows down the chemical burn and gains horse power. Much longer stroke with more pressure translates into more push on the piston thus more power to the ground. Only difference in most grades of gasoline is the volume of octane and alcohol per gallon. Christin if the only difference is the amount of octane and alcohol in both of those grades ..then that difference has to amounts to some of the volume, right? So if you took two samples of premium in different containers and in one you remove the appropriate amount of octane and or alcohol to turn the premium sample into regular. My 1st question would be, how much less volume would the regular gas sample be ? My second question would be ,...what do petroleum company’s use to fill that Regular sample can back up to one full gallon because that’s how they sell it, by the gallon. If you’ve removed part of the volume you have to replace it with something equal in volume...What ? They’re referred to as additives and amount to inert ingredients that don’t burn but whose volume is equivalent in weight to the octane and alcohol that was removed. So although they are equal in volume they contain different chemistry and burn differently, thus the power achieved by each one is also very different. You could probable get that boxer to run on kerosene and alcohol if the mix was right. But low octane gas is not equal to premium grades except in volume. When I bought gas as a kid in the 60’s from a company named Sunoco Oil they sold a premium grade who’s name was 260, ....Sunoco 260 ...and it was touted as very high octane and was racing fuel, because of the high volume of octane. It was even better than Avgas at the time but as pollution control was catching on it was deemed as dirty and they started dumbing it down so now it’s sold as 100 octane. Still sold as racing fuel. Much of the levels of octane relate to levels of pollution as well as the level of power. Aviation gasoline is just like auto gas but it contains an octane called tetraethyllead because is enhances the length of burn and gives a higher power output for gasoline aircraft, but the emissions won’t pass when used in an automobile or motos. I’m not a petrochemical engineer but the major differences in gasoline’s is level of octane, lots of subtitle differences, enhancers and additives but The primary difference is in how much octane ... Pretty sure. Blitz
In an engine designed to use regular gas, premium will not yield higher horsepower. Engines designed for premium will have some combination of spark advance, valve lift, valve dwell, squish area shape, or piston design that requires the slightly slower burn. All of those same characteristics are present in a lower octane engine, but at less aggressive settings. The engine designed for regular is incapable of benefiting from the slightly slower burn and higher ignition temp and the slower burn may leave carbon deposits in your combustion chamber and on your valves. The more important consideration now is the detergent additive package. Use AAA or Top Tier's website to see if the brand you're using is acceptable.
 

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Don’t know whether any truth in this, but, I’ve been told that the Premium Unleaded that Supermarkets sell is inferior to similar Premium Unleaded from the likes of Esso and Shell etc.
Ken.
There is truth to that. The octane will likely be as advertised so long as the law requires them to post that rating. The differences arise in detergent additive packages. Google "Top Tier Fuel" and you should get some information on the differences. I don't know if the UK has a similar organization.
 

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Have a 18' scrambler ,and my USA manual calls for reg 87 AKI as well.Interestingly,official BMW motorrad specs for that model year (and every other year) state under fuel requirements , " premium gas" . I run premium 93 and performance seems very good and no different after running a couple tanks of reg 87. Getting about 42 MPG .A bit of a head scratcher .
 

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Let’s not forget....the American gallon has less volume than an Imperial one. Just sayin’.
Ken.
 

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Have a 18' scrambler ,and my USA manual calls for reg 87 AKI as well.Interestingly,official BMW motorrad specs for that model year (and every other year) state under fuel requirements , " premium gas" . I run premium 93 and performance seems very good and no different after running a couple tanks of reg 87. Getting about 42 MPG .A bit of a head scratcher .
Maybe give US Motorrad customer service a call and ask them to clarify. Let them chase their tails for a bit....lol.
 

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Maybe give US Motorrad customer service a call and ask them to clarify. Let them chase their tails for a bit....lol.
I'm shooting them an email as we speak.Would love to see what that customer service person does with that discrepancy.Surely he/she has hotline to Berlin engineering dept....If no good answer,my german a little rusty but visit to Berlin HQ next ;)
 

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I'm shooting them an email as we speak.Would love to see what that customer service person does with that discrepancy.Surely he/she has hotline to Berlin engineering dept....If no good answer,my german a little rusty but visit to Berlin HQ next ;)
Absolutely. Bring your bandito mask.
 

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In an engine designed to use regular gas, premium will not yield higher horsepower. Engines designed for premium will have some combination of spark advance, valve lift, valve dwell, squish area shape, or piston design that requires the slightly slower burn. All of those same characteristics are present in a lower octane engine, but at less aggressive settings. The engine designed for regular is incapable of benefiting from the slightly slower burn and higher ignition temp and the slower burn may leave carbon deposits in your combustion chamber and on your valves. The more important consideration now is the detergent additive package. Use AAA or Top Tier's website to see if the brand you're using is acceptable.
Christian, Is our boxer at 12:1 designed for one or the other, premium or regular? Is it halfway between? I ask because I can physically feel the difference between fuels with more octane. I run a blend (as often as possible) of Avation fuel and typical high octane gas in Blitz and she perks-up considerably. It’s 4 times easier to lift the front wheel in first and second gear when under heavy acceleration. I’m not sure if she’ll go any faster top end because I draw the line at about 135 on the clock (probably not more than 120 actual mph) but I am certain she gets there quicker by a couple of seconds. No doubt in my mind. What do you think Christian, is she engineered such that some more performance actually can be obtained by using higher octane fuels ... I’m convinced she is, I can physically feel the difference and I’m certain you could read the difference on a dyno. ......Blitz
 

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I'm not dissing any other's opinion on this thread but I have to agree with @BlitzSchnell I definitely feel a difference between regular and high octane fuel on my bike, be that supermarket brand or Shell V-power (have tried the experiment with both over the years). I honestly don't think I'm imagining it, cause speaking as a canny scot, if I felt no difference I'd be happy spending less of my cash! LOL
 
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