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Think of the choke on older bikes...

If I had to guess, I would suspect that there is a calibration issue in the ECU program based on reports in this thread.

Seems this condition happens when the bike is switched off at warm(er) ambient air temps, and restarted after sitting a few hours when the ambient air temps drop more than 15F.(?) The ECU remembers the last temps, doesn't read the new temps, and sets the starting enrichment to the last known warmer air, thus no start. On the second try, as fresh air has now been drawn past the air sensors during the previous cranking, the new temps are now seen and a correct starting enrichment table is used, and the bike starts right away.

I have seen this before when I used to program ECU's for cars.



As for using a battery tender, I could also guess that when the tender is hooked up, the CanBus on these does "wake" itself every so often to confirm the tender is charging, as not to shut off the 12V plug, and in doing so it could refresh the air temp sensor so the bike sees a more recent value to calibrate the starting map.


Please understand this is just my theory as an owner, and I have no BMW equipment to verify values or do testing. I am basing this on my knowledge of fuel injection programing, and the fact that my bike and others experience this during seasons of large daily temp fluctuations. I suspect next winter to spring this topic will surface again. If it does come back again for me, BMW warranty will deal with it.
 
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I’d like to reinvigorate this post with my findings after 10,000 miles on my bike since April.

My scientific opinion at this stage is that this slow starting long cranking business ONLY ever happens to me when I use a fuel grade higher than 89 (I’m in the USA). 89 is what the manual calls for and the bike clearly favors this over the higher octane 91 and 93 grade fuels.

Understanding what octane is and why certain engines require higher levels of it makes my assessment add up perfectly.

The advance, compression ratio and fuel mapping of our LC bikes is specifically designed for one octane rating. When introducing a higher octane fuel in to the mix, ignition becomes more difficult as higher octane fuels require hotter spark/hotter advance/higher compression (any combination of these factors).

Thus when trying to start the bike from cold with an octane in excess of what the bike is tuned for it cranks and cranks while trying to fire the fuel designed to withstand factors greater than the engine is producing.

Having run only 89 since the middle of the summer I haven’t had a single long crank.

My 2 cents.
 

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Great that that's working for you Laharrier, and maybe that's even it. But...I always use 91 and 93 and haven't seen the problem in a very long time. I thought @dgiturbo 's theory sounded awfully good though. I once thought I had found a pattern and a solution to this only to have the problem pop up again to let me know that it had only coincidentally gone away.
 

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Great that that's working for you Laharrier, and maybe that's even it. But...I always use 91 and 93 and haven't seen the problem in a very long time. I thought @dgiturbo 's theory sounded awfully good though. I once thought I had found a pattern and a solution to this only to have the problem pop up again to let me know that it had only coincidentally gone away.
Right on. Can I ask why you use higher octane than specified?

I long did this as well thinking it was somehow “better” for the engine - but studying how engines are engineered and the purpose of octane was a breakthrough for me. There are no gains to be had using higher octane than required and it is likely that it actually causes a less complete burn/poorer ignition.

Sometime this think about 😉
 
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Probably no good reason! I think I suspected that BMW specified 89 as a "minimum" but that perhaps it would perform better a notch up.
 

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Mark – Moderator 2015 R1200R-LC Exclusive
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Probably no good reason! I think I suspected that BMW specified 89 as a "minimum" but that perhaps it would perform better a notch up.
Stale fuel can sometimes lose its octane booster compounds, but from what I've read, higher octane fuels are more prone to this (and I don't mean just fuel that has been in your tank for a while, but also fuel at a service station that has low turn-over of that fuel type).
 

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There is a discussion on FB at the moment in one of the R1200R groups around fuel. I have been using 95RON as that is what is I'm my manual and only using 98 when 95 want available.

Someone in the US posted up that their manual specifies 98 RON for best performance but you can use 95 RON just with less power and worst economy. She had an '18 model where as I was reading my '17 book.
 

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...

Someone in the US posted up that their manual specifies 98 RON for best performance but you can use 95 RON just with less power and worst economy. She had an '18 model where as I was reading my '17 book.
I’m calling BS on this. The latest US manual from BMW Motorrad states 95 RON as the required fuel and all non-ethanol petrol has the same energy density. Octane rating is related to anti-knock characteristics; if the physical characteristics of the engine that affect compression ratio are unchanged, then there’s no need for higher RON.

So if the engine is designed to run efficiently on 95 RON, nothing is to be gained by running 98.

Sounds like an oil thread to me ...
 

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I was going to grab the shot of the manual posted to see where it had come from but the whole thread looks like it has been deleted, lol. Definitely like an oil or tyre thread. :)
 

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I’m calling BS on this. The latest US manual from BMW Motorrad states 95 RON as the required fuel and all non-ethanol petrol has the same energy density. Octane rating is related to anti-knock characteristics; if the physical characteristics of the engine that affect compression ratio are unchanged, then there’s no need for higher RON.

So if the engine is designed to run efficiently on 95 RON, nothing is to be gained by running 98.

Sounds like an oil thread to me ...
For me, the ethanol part is the catch. I habitually use 91 AKI in all my bikes, to avoid ethanol as much as possible. The manual for mine (Canadian) says 89 AKI. I've never had an issue with any of them. On my old F800GS, I regularly rode in remote areas where 89/91 was unavailable, so I'd use 87. No power issues with that, but fuel mileage would suffer noticeably.

Oh, and I always use a special 78% nitrogen mixture in my tires for best performance and pressure reliability.

PS Manuals are readily available on BMW's Web site if anyone's looking for one.
 

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I clipped this photo out of the ‘17 handbook, it’s from the refueling section of the handbook and posted it up, as that is the section the other person posted up. No idea if they were using the wrong manual, or where they got the picture with the contradictory info from though.

//Dennis.
 

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Mark – Moderator 2015 R1200R-LC Exclusive
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I avoid E10 fuel as a matter of principle - last time I did the calculations the lower energy density (and hence poorer fuel economy) wasn’t worth the few cents per litre saved. And I’m a distrustful old sod.
 

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I avoid E10 fuel as a matter of principle - last time I did the calculations the lower energy density (and hence poorer fuel economy) wasn’t worth the few cents per litre saved. And I’m a distrustful old sod.
I've never really cared all that much about energy density, whatever that is :wink2:

But as a card-carrying male citizen of Canada, I have a chainsaw. We all have chainsaws. It's a legal requirement to carry a chainsaw, even when buying groceries. The plastic cap on the gas tank of mine is swollen so much from E10 that I can no longer remove it by hand. I can't leave gas in the tank because of this. Which makes it pretty much useless as an every-day-carry anti-zombie tool. I have to resort to carrying my Swedish brush-clearing axe.

There have been numerous issues around E10 and plastic motorcycle fuel tanks and other parts, particularly older ones. Search for PA6 polyamide plastic and motorcycle for details. I won't even go into the whole issue of using farm land to produce gasoline products, or phase separation in stored E10.

Like you, I'm a distrustful git. Not old though :grin2:
 

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Oh, and I always use a special 78% nitrogen mixture in my tires for best performance and pressure reliability

ROFL!


Whenever someone mentions special nitrogen fill for tires, I point out that:
- the thermal expansion coefficients are0.00369 1/K for air and 0.00368 1/K for nitrogen (i.e.,the difference, 0.3%, is negligible) and that,
- if it were true that oxygen diffuses appreciably more quickly from the tires, you would end up an with increasingly high concentration of nitrogen anyway.


The stares are usually blank :)
 

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Mark – Moderator 2015 R1200R-LC Exclusive
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ROFL!


Whenever someone mentions special nitrogen fill for tires, I point out that:
- the thermal expansion coefficients are0.00369 1/K for air and 0.00368 1/K for nitrogen (i.e.,the difference, 0.3%, is negligible) and that,
- if it were true that oxygen diffuses appreciably more quickly from the tires, you would end up an with increasingly high concentration of nitrogen anyway.


The stares are usually blank :)
Well ...
 

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ROFL!


Whenever someone mentions special nitrogen fill for tires, I point out that:
- the thermal expansion coefficients are0.00369 1/K for air and 0.00368 1/K for nitrogen (i.e.,the difference, 0.3%, is negligible) and that,
- if it were true that oxygen diffuses appreciably more quickly from the tires, you would end up an with increasingly high concentration of nitrogen anyway.


The stares are usually blank :)
oh, my head hurts ... i got first and the last part, just not clear on the middle part...:dizzy:
 

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Mark – Moderator 2015 R1200R-LC Exclusive
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ROFL!


Whenever someone mentions special nitrogen fill for tires, I point out that:
- the thermal expansion coefficients are0.00369 1/K for air and 0.00368 1/K for nitrogen (i.e.,the difference, 0.3%, is negligible) and that,
- if it were true that oxygen diffuses appreciably more quickly from the tires, you would end up an with increasingly high concentration of nitrogen anyway.


The stares are usually blank :)
I've sometimes wondered whether water vapour in tyres (e.g. evaporated tyre change lubricant) makes any difference to pressure with temperature change compared with dry air. I've never been motivated to work it out, though.
 
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Just wanted to pop back in here with an update that after about 3000 miles of using 89 AKI exclusively, I have no experienced a single hard start. Im convinced the octane is the cause and effect. Higher octane: harder to fire. My 1200 is designed for 89 AKI and that's what it likes. Averaging about 55mpg also.
 
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