Topic: Headlight affects recharging and other things/1975 HOnvda 550/4

[43and countiing]

So my battery wasn't charging and my mechanic tested the voltage regulator finding it was non-functional. Strangely, I had to finish a 300 mile ride with the headlight off. He replaced it with a rectifier, and all seemed well. We then changed out the OEM headlight, with a modern H4, and I soon had some problems. Namely, the left turn signal wouldn't work unless I got up and held rpm's at about 3000, and the battery would slowly drain.
I put a new gel battery in, and it was great for the first 20 miles and then all the symptoms came back. Replaced the bulb itself, I think to a 55W, and the problems just continued. Out of frustration, I put the original sealed beam headlight back in (I think it said 35/40W on the bulb itself). Fixed everything...weak spark, etc etc. Everything works great again. I thought I once read in the original Honda literature to never replace the bulb with anything else as the electronics were not designed to handle it. The headlight, like it's owner, may not be the brightest bulb in the box, but it works. My concern is if it ever burns out, are there sealed beams of OEM ratings still available? any other thoughts?

[TwoTired]

Regulator and rectifier are two different functions. The 550 originally had one of each. Newer aftermarket units often combine the two functions in a single unit, though.

 The stock headlight was a 40/50w unit.  I've used a 55/60 with some success.  But, the charging system is taxed with using that or more wattage.  All are significantly less bright when it receives low voltage.
 And, the regulator/ alternator function can't do their job properly if if receiving lower than battery actual voltage.
Its not uncommon for the wiring connectors and switches to degrade and lower the voltage being distributed.

It is not clear whether your original rectifier and regulator were actually faulty, as from your report you paid to have the bike repaired and it wasn't, they just charged for a shotgun parts replacement guess and labor.  This does cast doubts upon your mechanic choice.

Do you want to learn enough to fix it correctly yourself?  Keep replacing parts until it functions like it should?    Take it back to the original mechanic for another attempt at repair?  Or, shop for another hopefully more competent mechanic?

We can help you fix it yourself, but you will have to do the work and be eager to learn.  You also will need some test tools, such as a multimeter, to take accurate readings and report them to us to make a proper diagnosis.

Which path seems attractive to you?

Cheers,