dickie wrote:I drilled the holes a little further and tapped them so that they accept the full 17mm of thread on the MB studs. I'll probably use piaggio m8 next time, but I'd ordered these before you told me. C'est la vie.
Regarding geometric versus corrected, I suspect I'm about to open a can of worms, but corrected makes more aense to me, although the reflection from an expansion causes me to doubt my own opinion. I'm going to be running this with a clubman which I think makes that less of a concern and corrected ratio therefore more relevant?
You should choose your preferred method in assessing the compression ratio & stick with it for consistency.
The corrected compression ratio does presume that the volume of head & cylinder is only applicable upon closure of the exhaust port, but the reflected wave of an expansion chamber/exhaust should be doing some kind of job in closing off the port to stop the fresh charge evacuating itself, shouldn't it?
Besides which, the uncorrected compression ratio does not change with any modification to exhaust port timing & therefore height/closure point & can be set prior to the porting of the barrel.