You're on the right track with the seat latch: the K0/1 frames were different under the seat from the K2/6 versions. The K3-6 versions had the main wire harness ground at the front coil's mount (bared of paint there) while the K2 had it at the middle of the bike, on the seat latch. The K0/1 also have it at the middle of the bike. Once in a while I have also seen some K4 bikes with the ground lug at the seat latch, not sure 'why'?
The K0/1 frames often needed drain holes drilled (7/64" or 1/8" drill) just forward of the lower front engine bolsters, both sides, as the lower bolsters are set deeper into the frames than are the later ones. The K0/1 frames also sometimes have a fully-welded plate at the junction of the middle downtubes to the lower cradle, with no open holes there. Some were corrected in the later "New Factory" K1 frames, but most needed a similar drain hole below those plates for seepage and condensation to drain out behind the rear lower bolsters.
The K2-6 frames were made with thicker, less-easily-corroded steel, too, but that is hard to tell from 'outside'. The mounting plate for the lower front right engine mount will fit both versions of the frame, but you might find a 1mm misalignment (I forget if it was 'up' or 'down') for the engine when a K2-6 triangle engine mount is used at the lower right site. A K0/1 mounting plate will cure that, but so will a drill...
Thank you Mark that is helpful direction.
So the slide latches of the K0-K1 have different bolt patterns than the K2-K6? I haven't had any K0-K2 to work on to know them but have a friend @60 miles away with a couple of K1s that I could ride over and compare and another friend with a K2 @40 miles from me.
Were the harness ground wire lugs bolted to the seat latch bolts and coil mounting bolts or with a separate bolt thread/hole in the frame specific for the grounds?
In 2020, stuck in San Diego, I stripped a K4 frame and painted it for a friend's bike. I do remember there being a ground lug at the seat latch area, but I think I remember there being a ground lug at the coils too, but my memory isn't real clear on that point nor do I have any pictures of the coil area showing the ground there. The seat latch area pictures don't really show where the ground is bolted at in my picture.
I have a couple K4s and K6s along with my K5 in my shop to look at to investigate the ground wire lugs and measure later in the week when I get back in the shop.
Gurp
Yes I had a couple onlookers while I was strapping it on the bike and a few puzzled looks from passing bikes on the road.
Yes Per the paint is mostly perfect with a couple spots needing touching up from storage scuffs. It put a glimmer in my eye as I looked it over through the holes in the plastic Honda parts bag.
It's not what I would call high gloss but close.
He said he had started asking $500 at the beginning of the day, and mentioned he was down to $250 when I first started talking to him about it, 20 minutes later after poking around his other stuff and asking what else he had at home for 750 parts he said he had, he offered it to me at $200, so I pulled it out. I didn't even have to haggle with him. I spent 30-40 minutes talking to him and his dad reminiscing of rides and of a K0 750 his dad had bought new, did a few bolt on mods to and street and track raced against 900 Harleys and stomping them. It was a great visit meeting new friends. I'll have to ask him if he's the one that had a frame on Craigslist last year listed at $800....
Bryan
I asked him if he had gotten any stamps from the dealer in his parts purchase as he said he had gotten some tools....but no stamps....
I'll have to pick an old friend's brain that was a service manager to see what he remembers on the stamping they might have done.
Anyone have pictures of the K0-K1 seat latch frame bolt hole area to compare?
I've had some thoughts a few months ago of putting together a bitsa bike with a K0 duck tail seat and paint scheme.