I just did a rebuild on a friend’s Yamaha rookie motor. Parts cost was under $200 with a few carb rebuild kits etc. The crank was among the straightest I’ve seen (less than .0005″ on each side) and the lower rod bearing had virtually zero play so we didn’t separate the crank. We did new main bearings, seals, cylinder hone and top end, along with measuring /checking to be sure the port timing and cc’s matched the engine builder’s specs. In all, it took about 5 hours labor. Still a pretty cost effective engine package in my opinion.