High octane fuel necessary?

Howdy Howdy all!

What an awesome week we're having, in comparison to last week and the potential noah's ark floating down my street! Anyway, I'm kinda not sure about what grade fuel I should run on my old BMW. (1976 R90 to be exact) I was told, by what is historically an unreliable source, that since my engine is a high compression engine (158 left 156 right) I need to run high octane fuel. Is there anyone who can support/debunk this? ****, I don't even know if that compression is high or not!

Gracias,
And I hope we're all taking advantage of the reborn summer!
Charles

I doubt seriously that you need anything more than Regular, 87 octane gas. I am not really familiar with the Beemer but even for the high performance race replica bkies liekt eh GSXRs and CBRs, they run on regular. Might try going to a beemer owners group and asking the question.

Good luck

From what I've gathered over the years, high compression singles and twins do tend to require higher octane ratings than production motors, and my experience with a variety of bikes supports that. Most stock production bikes should run okay on 87 though. I'd try high octane for a while, see if there's a difference in performance, mileage and running temperature, or if there is detonation with 87. My air-cooled engines seem to run cooler and show less power-fade on higher octane, especially the singles. You might try a beemer forum or something on the internet that will answer better.

SVinAustin said:

I doubt seriously that you need anything more than Regular, 87 octane gas. I am not really familiar with the Beemer but even for the high performance race replica bkies liekt eh GSXRs and CBRs, they run on regular. Might try going to a beemer owners group and asking the question.

Good luck

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My CBR requires 91 or better and all the gixxers I have sat on at dealers said 90 or better.

MY VFRs = 87 octane and they run great. My R1150GS, 89 min according to the manual. Haven't really experimented with different octanes in the BMW just yet.

Adios,