These new 66mm bore with 4mm to 6mm stroked cranks are just way to fast, IF you use the right builder.
Heck I couldnt handle the one I had. But willing to help those in the search for speed.
What if i told you today that i found a crankcase and crank that gives 44mm stroke and with a bit of machining will accept the 090 cylinder and give you 148cc .... physical size of the cylinders is very close to each other
Whoo hoo and i was gonna buy a 3120 with an already weak bottom end no need to now ..... now to try and hide it all inside a standard saw ............ what this space ............ McBob.
P.S. And the donner saw well you can go and work it out for yourselfs