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markjenn markjenn is offline
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Join Date: Nov 1999
Location: Bellevue WA
Posts: 3,603
This might be something to fiddle with but I find the author's cavalier attitude towards detonation off-putting. He recommends bumping the timing up an arbitrary amount and if it doesn't ping during a test ride, you're good to go. IMHO, that's an irresponsible way to represent the tradeoffs of advancing the ignition timing beyond stock.

An engines octane appetite is highly dependent on a variety of factors that the rider can't control. An engine that doesn't ping during a 15-minute test ride around the neighborhood could easily hole a piston in five minutes the first time you head up a steep grade on a hot day with your wife on the back. And in my experience, R1100's need all the octane they can get - many (most?) will ping even on premium in hot weather under high loads. Lots of owners complain of pinging problems.

I have also heard that BMW ECU's have an ignition timing "trimming" mechanism where under steady state conditions, the timing is automatically advanced a small amount with the idea that under steady state conditions, you can afford a little more advance without danger. This is another variable that probably would never show up in a test ride.

I also note a factual error at least for the R110S: BMW doesn't recommend "mid-grade" - the spec for US bikes is premium 95-RON/85-MON which is generally 91 pump or higher. I had thought that all the R1100/1150's required premium, but perhaps the lower-tune models allow mid-grade.

Again, fooling around with trying different advances might be something to try on your individual engine to assess the tradeoffs, but you need to be careful and understand you're using up some of your safety factor.

- Mark

Last edited by markjenn; 06-28-2007 at 02:00 PM..
Old 06-28-2007, 01:58 PM
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