next, burning oil. now this little engine was the butt of a joke at some stage. When I rescued it from under a tree and stripped it I found a wood screw imbedded in the piston. as a consequence the inlet valve was bent and seat damaged. new valve and seat repair think no more. now Taddy holds 900ml of oil so using about a litre for the 1600km is no biggy cause I carry two litres... but have a look at these pics
here is the piston not quite finished machining it to get 10.3 : 1 CR and very good valve clearance.
you will notice that the carbon from the burnt oil has filled the valve ports and lined the combustion chamber this will have raised the CR well towards or past 11 : 1 CR. I think 11 : 1 is really pushing it on 98ron in a hot little air cooled motor. To give an idea the final cut on the crown of this piston was 0.6mm witch dropped the CR from 10.8 to 10.3 so you can see how the carbon deposits increase the CR.
These are not very good pics but believe me there has been a bit of detonation due to the increased CR and the piston, chamber and edge of the copper head gasket are showing signs of erosion.
Now, detonation will cause the compression rings not to seal in the bore and increase crank case blow by not to mention engine meltdown. this event would be categorised as a walk, not a SS or BB.