since I'm at home with lot's of time, but not enough healthy thumbs to do some work on bikes ,
I created this excel file to calculate combustion chambers.
added/changed some cell-remarks, and secured the file, so one can't accidently change formula's.
you can easily change the security settings (if you want to change/add something) by clicking on the "check" page at the top. For further info, type "securing excel files" in google, like this one :