My main concern was upgrading the alternator. Any guesses on possibility of swaping out components from newer bike? I found this but for CBXs...
http://www.cbxman.com/detail.aspx?ID=577 Its a retrofitted kawi alternator that bumps the cbx alt to 430W from 350W - THIS is what I'm looking for my 72 750k
Hondaman: Can you just swap out any old component? I might be a total ignorant noob here, but do you need these units to have the same "specs" as the ones I am replacing or are all regulator rectifiers built equal? If it looks the same will it work the same? It looks like the starter relay is 79 EX500 but and starter sucks the big one right now but I don't have a voltmeter to check the battery yet.
-Alex
Within the Honda family of products from about 1969 to 1978, the electrics all had very similar specs and ratings. Sometimes the connectors or the pinout arrangements in the connectors changed, but the parts from a CB750, for example, would run any other Honda in that period. The 750 had the strongest alternator at 310 watts (generally underrated), and aftermarket winding companies would add some more wires to the windings or build shims for those fields to boost it to 350 watts for tourers who wanted bigger lights.
Generally, today, I would replace the taillight with LED lamping, install a 3-terminal solid-state flasher and LED turn lights, run extra headlight wires and install 50/55w or 55/60w headlight as upgrades. The wiring harnesses will generate bad splice joints over time if you just install a 55/60w (or higher) headlight without running separate wires. The same can be said for using high-current coils, like the 3-ohm DYNA III units, from the stock wiring harness: add a separate 16 AWG wire to feed the coils: tie it in at the main fuse, after the key.
The starter solenoids, despite for their different-looking terminals, all carried 70-80 amps at 12vDC, and most can be disassembled and the contacts repaired (i.e., cleaned up with a relay file), and reassembled to work a long time. Clean the rust out, too, and add a drop of oil around the coil. The rectifiers for the 750 carried up to 35 amps, the ones for the 500/550/450 twin carried 22 amps, and the old 350 twins carried 20 amps. The 750 could replace them all, with improved results. I also made some for racing that had 40 amp silicon diodes on heat sinks (at the user's request; heck, he was paying for it...) that made no appreciable difference.
The regulators tend to pit their contacts and need occasional cleaning up with a relay file. I think I actually adjusted one once, but other than that, never saw a bad one. Two Tired seems to have done more of these than I have...
If you build a whole new wiring harness, use 18 AWG as your minimum size, with MTW insulation (not PVC), and run 14 AWG as the main "backbone" feeder, splitting it to 18 AWG wherever an original joint was found. The harness will grow in diameter about 1/4", but will still fit everywhere. Wrap the whole thing with no-stick electrician's PVC or mylar wrap (industrial supply houses have this stuff), tying off the ends with ty-raps for convenience and a nice, finished look.
Generally speaking, the larger alternators will add harmonic balance issues to the crankshaft that you might not appreciate. In the case of the CBX, there is a lot of crank mass, so a 15% increase in the alternator's not so bad. On a 500, this will be a lot. On a 750, it will drop HP by almost 1, and it will rev up noticeably slower. Keep these things in mind, if swapping alternator rotors. Also, divide the alternator output (watts) by 12 (volts) to get amps: this is to see if the rectifier you have can take the current it will generate.
Often, 750 roadracers would go the other way, using a 350 Honda or 305 Honda alternator in place of the stock units. All you had to do was mount it...
