Originally Posted by Maddin21

The Orion Alpha .12 are based on or actually are Sirio XXX engines.
The Evo 4 had a different bore and stroke...and the well known sleeve layout.
The XXX engines have a much shorter liner where the TDC is the top of the sleeve.
So both...p/s sets and combustion chamber are different between both engines.
Same for the crankshaft...

Conrod and bearings are interchangeable...


--- MARTIN ---