I hope this may help some of you. Before I start I'll tell you a little about my bike as it is in a specific state of tune that will be sensitive to fuel quality. It's a 1976 R90/6 that's gas flowed for fast road use and twin plugged as well as running electronic ignition with retarded timing. The carbs are standard 32 Bings with a lean mixture set-up that's just the optimum side of too lean; it gives high mpg's and is a quick bike by any standards. It also has a deep oil sump for a little extra oil quantity (not worth it as the engine breaths oil down to the level it wants anyway) and I run an oil temp dipstick to monitor oil temp.
As I'm long retired I ride this bike a lot around fast A and B roads that we are fortunate to have in Lincolnshire; I usually do about 100 miles and maintain a good pace and as a result I am in tune with the bikes performance.
I tested with a FULL tank of Shell V-Power, followed by a tank of Shell E10 standard unleaded and then another full tank of Gulf E5 Endurance super unleaded.
Previously and prior to the new E10 I normally used the cheapest supermarket fuel and put 1/4 bottle of Redex in a full tank and the bike ran perfectly. I also have the cleanest carbs and fuel system you've seen, look like they have just dropped out the ultrasonic cleaner.
I first put in the Shell and ran the tank down over the usual fast roads over two days, noting the performance, mpg and temperature that the bike ran at ( Also have a digital temp measure for immediate direct comparisons). The bike flew and pulled hard from idle to redline with no other issues noted other than a particular smoothness that I hadn't achieved with the supermarket fuels. All good.
I then put in standard E10 unleaded without Redex and repeated the same rides. I did notice some differences which I'll discuss at the end. For comparison I then repeated the whole process again with E5 Super unleaded just to see if the differences were real or imagined.
Here's what I noticed: On E5 Super unleaded bike was perfect and smooth giving good mpg and ran at a constant temperature with no issues (as you'd expect). On the E10 fuel the bike was noticeably not quite as smooth and pulled better from 3500 rpm with wider throttle. I couldn't differentiate a change in mpg and although I thought the bike ran slightly hotter I think with hindsight it was the ambient air temperature that had the biggest affect of about 20 degrees F, not the fuel. One big difference that I noticed and had to check frequently was the performance on closing the throttle: as we all know shutting the throttle on a boxer is like a third brake and something that you get used to. On the E10 fuel I found that shutting the throttle had a quite severe reaction and an increased braking action on the bike, whereas with the Super unleaded on shutting the throttle it's a much less pronounced reaction and less braking affect. I primarily ran the test again to check this reaction and it is definitely there with E10 fuel. I checked the fuel float levels with both fuels and there was no difference as you'd expect, but I didn't weigh the floats as they had not sat in the E10 long enough.
So, in summary, what do I surmise: I would happily use E10 if that was all that there was available but in future I will strive to find Super unleaded. The performance differences were there but you need to be looking for them and for touring / long distance blasts you probably wouldn't notice the difference or would adapt to them. BMW say that the o=rings, floats and rubbers in the carbs will not be affected by E10 but only time will tell on that one.
I hope this is of some use if you're thinking about it.
PS: The 90/6 is a nicer ride than the S
As I'm long retired I ride this bike a lot around fast A and B roads that we are fortunate to have in Lincolnshire; I usually do about 100 miles and maintain a good pace and as a result I am in tune with the bikes performance.
I tested with a FULL tank of Shell V-Power, followed by a tank of Shell E10 standard unleaded and then another full tank of Gulf E5 Endurance super unleaded.
Previously and prior to the new E10 I normally used the cheapest supermarket fuel and put 1/4 bottle of Redex in a full tank and the bike ran perfectly. I also have the cleanest carbs and fuel system you've seen, look like they have just dropped out the ultrasonic cleaner.
I first put in the Shell and ran the tank down over the usual fast roads over two days, noting the performance, mpg and temperature that the bike ran at ( Also have a digital temp measure for immediate direct comparisons). The bike flew and pulled hard from idle to redline with no other issues noted other than a particular smoothness that I hadn't achieved with the supermarket fuels. All good.
I then put in standard E10 unleaded without Redex and repeated the same rides. I did notice some differences which I'll discuss at the end. For comparison I then repeated the whole process again with E5 Super unleaded just to see if the differences were real or imagined.
Here's what I noticed: On E5 Super unleaded bike was perfect and smooth giving good mpg and ran at a constant temperature with no issues (as you'd expect). On the E10 fuel the bike was noticeably not quite as smooth and pulled better from 3500 rpm with wider throttle. I couldn't differentiate a change in mpg and although I thought the bike ran slightly hotter I think with hindsight it was the ambient air temperature that had the biggest affect of about 20 degrees F, not the fuel. One big difference that I noticed and had to check frequently was the performance on closing the throttle: as we all know shutting the throttle on a boxer is like a third brake and something that you get used to. On the E10 fuel I found that shutting the throttle had a quite severe reaction and an increased braking action on the bike, whereas with the Super unleaded on shutting the throttle it's a much less pronounced reaction and less braking affect. I primarily ran the test again to check this reaction and it is definitely there with E10 fuel. I checked the fuel float levels with both fuels and there was no difference as you'd expect, but I didn't weigh the floats as they had not sat in the E10 long enough.
So, in summary, what do I surmise: I would happily use E10 if that was all that there was available but in future I will strive to find Super unleaded. The performance differences were there but you need to be looking for them and for touring / long distance blasts you probably wouldn't notice the difference or would adapt to them. BMW say that the o=rings, floats and rubbers in the carbs will not be affected by E10 but only time will tell on that one.
I hope this is of some use if you're thinking about it.
PS: The 90/6 is a nicer ride than the S
