What a job!!
The fin repair is amazing, I didn't know that was possible.
Following with great interest.
Yeah, this guy is amazing! I met him when I was building several classified machines for ordinance suppliers. He is local, an immigrant from Czech Republic about 40+ years ago. I've not met any other welder who can draw a solid arc across open air like this guy can, and if it wasn't for the need of a sandy finish on these fins, you'd never know it wasn't OEM. He's repaired more than 20 such fin 'accidents' for me, and all are works of art and their shapes, even outer edge trims, are identical to the others. It wasn't terrible: around $500 to restore 9 fully missing fins that were NOT connected to the inner sleeve core of the cylinders - the sandcasts' outer fins don't contact the sleeve's bores, unlike the K0 and later versions, which do. It was this particular feature, very hard for Honda to build, that prevented these outer 2 cylinders from warping the way they do in the K0 and later engines. I'm not surprised it disappeared in later builds, given the fragility of this feature in real-life usage. But, the old bore sleeves had disintegrated like many sandcast ones have because they weren't yet destressed like the K0 and later ones were. So now it will be an OEM 61mm bore, as if from new.
I'm going to bring the cases to him, too, to rebuild the missing right rear thread bung for the 8mm bolt back there. He has also rebuilt an entirely missing top left rear bolt mount for me (K3, I think it was) on an engine years ago, by supplying him another one to look at while he did it, from scratch. After wet-blasting it looked factory! Once (another sandcast) I had him rebuild (in 3 steps) an upper case that had suffered a poor repair from a chain crash-thru, it leaked oil past the 2 lbs of JB Weld plugged all over because someone had overheated the cases with their fix-up welding attempt, warping everything. That one took a whole summer of back-and-forth between the welder and a machinist who knows precision (and tricks, and he makes swingarm collars for me) to finally get it to sealing again.
I still remember my Honda mentor Jim Chamberlain's sandcast (the first one sold in Peoria, IL, in 1969). At well over 100k miles he decided to rebuild it. He said it had started 'not being smooth anymore', so he had the crankcases align-bored to see if they had warped: they had, about 3 to 4 ten-thousandths of an inch each, he said. He rebuilt it with all new Black and Brown main bearings and one size smaller rod bearings (same crank, untouched) and last I heard had another 40k+ miles on it, pushing the #2 Vetter Phantom fairing all along the way, smooth as silk again.
