Hi All. It's been a while since posting. For the most part, I've been riding the heck out of the 750 Blaster and the blue 550. In the interim, I've been rebuilding my buddy's 1978 550K. I will supplement with photos of his bike later, but basically - new Excel wheels and SS spokes, polished hubs and engine covers, chromed swingarm, head ported with new oversize valves, rebuilt carbs, new roller needle swingarm bearings, new Web cam, new tapered steering head bearings, and new paint and seat. He already had a custom 4 into 4 exhaust made.
I wanted to share a short electrical story on this rebuild (no pun intended). After timing the new cam and adjusting the valves, I installed the cam cover, carbs and exhaust. I static adjusted the timing. Put the battery on trickle overnite. No issues the next day when connecting the cables to the battery.
After priming the oil galleys as much as possible by using the kick start lever, I went for the first fire up. All systems go. But when I hit the start buttom, the neg terminal of the battery starting a fireworks show and melted - it continued even after turning off and taking out the key. I had to remove the cable from the terminal to make it stop and I thought I was luck that the battery did not explode.
My first thought was hi amperage short, loose/bad frame ground, or a bad rectifier. I first checked the fuses - none were blown! Quite surprised to have the fuses survive such an electrical event. Then to the frame ground which is clean and solid. I unplugged the rectifier and touched the cable to the melted neg terminal. Major sparks. Ok, so I proceed to unplug the alternator gang. Touched the cable to the terminal...more 4th of July sparks. After pondering the situation for a minute or more, I swapped out the solenoid with a brand new one. Touched the cable to the neg terminal and .... nothing. Phew. So the problem was solved in less than an hour.
I progressively plug back in the alternator wires and rectifier. Touch the cable - still no sparks. Great - I switch to a new battery and connect both cables (positive first of course). Turn the key to on and the headlight, neutral indicator light and oil indicator light turned on. So far so good. I push the starter button and ...click, click, click, click.... Damn!! How can a second solenoid be bad?
So now I'm thinking the new solenoid is bad and use a screw driver to bridge the solenoid terminals. Small sparks but no starter engaging. OK, solved it. My buddy's 550 has a bad starter so I pull the sprocket cover and remove the starter motor. I bench test it and it revs like a bee hive. What the hell? I walk away and leave it for the next day after already ordering a starter rebuild kit on my cell phone.
Next day I disassemble the starter just to take a look. The brushes, comm., and windings look almost new. As I proceed to reinstall the starter, I see a slight metallic reflection. There is a very small 1/4" tear in the insulation exposing a tiny amount of copper wire. Ah ha! The pos cable to the starter was grounding out on the engine case because when I installed the sprocket cover with new allen head bolts, the cover ever so slight crimped the starter cable as I tightened up the 4 cover bolts. I think only by the grace of the Honda gods I saw the tiny glint of the exposed copper. I heat shrunk new insulation over the cable and CAREFULLY reinstalled the sprocket cover. After choking off the carbs, the old gal fired up beautifully - it growls - no oil leaks (so far) - no smoke.
This story re-emphasizes to me that most electrical issues are caused by a loose or faulty ground - which includes this unintentional and ever so slight grounding of the pos cable supplying (+) voltage to the starter motor. Thus, the hi-amp short.
Cheers - and check all your connections and grounds!
