Originally Posted by Kerry W
10:1 is certainly 'adventurous' on 92...I'd have expected not more than 9:1 and probably more like 8.5...

My XR400 has a standard 10:1 compression ratio and my friends KTM 640 has a higher ratio (I forget if its 11:1 or 12:1).

In the UK, standard pump fuel is 95 or "Super" is 97/98.

Neither of us have had problems using standard pump fuel so why should a GS need a higher octane rating.

Now I know that there is a 50 year age difference but surely its not just compression causing the knocking? I am not asking a question per se but just remarking on how two different bikes with similar CR's seem to react differently on pump fuel.