RE: Evolution break in?
James,
Two engines that were manufactured identically (CNC) and broken-in in the same manner, should perform similarly...
However, one of your engines is tighter than the other one is...
See why. I suspect a bearing may be unseated, causing the crank to rub on the back-plate...
I obviously cannot guarantee the break-in will even them out...
Contact Horizon and describe the problem you're seeing - stating both engines must be mounted on a twin.
See what they will do.