Long story, short - I impulse bought a partial NU50 engine on eBay last year after I bought my NU50. The original intent was just to have it for spare parts, and maybe just getting used to taking an NU50 engine apart. I just tore into it for the first time a couple of weeks ago, and holy rust.
I thought I would take a shot at cleaning up some of the parts with Evapo-Rust and see what happened. To be fair, Evapo-Rust has done a pretty good job at getting rid of the rust. However, there seems to be a lot of pitting from the amount of rust that has built up over time. That makes me wonder, are these parts even usable at this point? I would guess that the pitting isn't a huge deal on the kickstart gears/shafts/etc., but what about on the drive faces, drive boss, and clutch bell? Is there a good way to smooth out these surfaces, or is it even worth the effort?
There are other parts with an equal amount of rust, but I haven't started working on them yet. I guess if nothing else, taking things apart will be good practice before I work on my bike.