Welcome to MBc, Bob. Be sure to get acquainted with our search facility...it will lead you to just about any question and answer you could come up with about MBs. If that doesn't help read, read and read some more. Maybe ask a question in the proper Forum. You might want to start with this pdf file loaded by Loquin, one of our admin guys: Mini4BrochureWebSec.pdf If that's not enough, start with our 4-stroke engine Forum...there is a good discussion of the gx35 and Robin Subaru EH035 (my hands-down favorite.)