So far, I have built 8 BGF chinagirl engine builds in the last 2 years.. I didn't remove the heads or split the cases on any of them. I did remove all the covers and tighten every fastner I could find. All of them had not very tight screws on the magneto and case.
Had to tighten the internal clutch spring on several after break-in..
Also, I have never had to change any hardware except the bolts that clamp the chain tensioner. If yer careful and make sure the studs are fully seated in the engine, and don't over torque, or re-torque while hot, you prolly won't have any probs.
Somebody opened one up and saw some aluminum shavings and freaked out! So what, aluminum is soft and those tiny bits can't hurt the bearings or bore, so i don't worry about it, It'll all blow out when you start it LOL
No problems with the crankcase internals yet, except one engine that had an undersize crankpin. It ran fine, but rattled like crazy at full rpm. Pulled the head and jug to find this out. Added an xtra head gasket and it helped a little. The guy that bought it is an easy and cautious driver and never revs it enough to get it to rattle, drives it around in new Orleans French Qtr, and he's very happy with it.