I am immensely interested to see how this goes, as I will be purchasing a '77 CB750A that I want to convert to EFI with a few tweaks to improve performance (such as a cam swap, and possibly some chain gear teeth number changes as well).
I understand that this bike is a dog performance-wise by default, but I also plan on doing a complete resto on the rest of the bike, with only these couple of tweaks here and there, like the EFI conversion, and gear and cam swaps to improve the performance a little.
I am new to these forums, and will be posting pics of the bike in a couple months. Right now, the previous owner has it in the local shop where I drop parts off at from time to time (I work for a local napa auto parts store as a delivery driver/counterman), and the previous owner only wants $750 bucks for the bike. The only things that I can see wrong with the bike as it sits now, is it needs a tune-up badly (partly why it is in the shop now anyway), a new battery (previous owner has a battery cobbled into the original battery box, one that is too small for the box), and a few other odds and ends. The chrome pieces are a little pitted, but those can be re-chromed later, or even painted to match the tank color, and the tank itself seems EXTREMELY solid, no major rust spots and/or holes that need to be filled, not to mention that the seat itself has no rust on the underside to speak of, and the seat cover itself has no cracks at all! the frame is also still in its original powdercoat, with no obvious rust spots as well, except maybe for behind the front fork, near the base of the engine where rocks may have bounced up into it.
for 750 bucks, I can't really complain much about the bike, as come this spring, it will be fully working, and tuned with the original carbs in place.
This bike is in PRIME condition for my plans of semi-restoration, and, since honda made EXTREMELY few "hondamatic" bikes, it is sort of rare itself anyway. I do not plan on getting rid of this bike anytime soon, due to the rarity of these "automatic" bikes.
I understand that they were never really more than "commuter" bikes, but, with an EFI conversion, and a few drivetrain tweaks here and there, I may be able to salvage a little of the performance of the CB750 engine series.
Please, do post more on your progress of your build. This spring or summer, I plan on sourcing a complete CB750 engine/trans set from a salvage yard, and doing a complete rebuild on both the engine and tranny for when I do the restoration of the rest of the bike. I will be doing the EFI conversion on the rebuild motor, not the one originally in the bike now, so I have some time to see how well yours holds up (i.e. the rubber manifolds).