1966 Honda CL77 305 Charging Troubles

| 7/27/2016 12:00:00 AM

Motorcycle Classics tech expert Keith Fellenstein

Editor’s note: If you’re having trouble with that old Suzuki, BSA or BMW, Keith Fellenstein is your guy. From motorcycle tuning tips to detailed motorcycle engine repair, he can draw from a wealth of experience to help guide you to success. Send questions to: Keith’s Garage, Motorcycle Classics, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with “Keith’s Garage” as the subject.

Charging troubles

Q: I have a 1966 Honda CL77 305. We all know the charging system setup wasn’t the best on these 12-volt bikes. From the factory they were weak at best. I’m trying to figure out why the stator isn’t producing 60 volts to the rectifier? I have installed two different stators and replaced the rotor as well. I also installed a new rectifier and new coils. The bike now starts with one kick, but when I turn the lights on, I start losing the DC current, as shown using my voltmeter. I have checked the red wire, the brown wire and the yellow wire going to the rectifier, as shown in the manual. I have also replaced the headlight switch, and I’ve added a new wiring harness, too. I have also installed the electronic ignition from Charlie’s Place. The new battery is simply not getting up to 14 volts when lights come on. Lights on or off, the battery is losing voltage. I could go insane over this. Bruce A. Ferguson/via email

A: We’ve been fighting a losing battle with these marginal charging bikes ever since full-time headlight use became law. It used to be that the bike would mostly be used during the day, long enough to barely get the battery to full charge. Then if you had some night riding, it would drain the battery, but hopefully not so much that you couldn’t make up the deficit the next day. I’m not sure those machines ever managed to charge a battery to 13 volts, much less 14 volts. I think your best bet is a battery tender, since you’ve replaced all the components with no improvement. MC

8/12/2016 9:54:37 PM

You may want to consider changing your tail/brake light with an LED bulb. This will reduce some of your bikes power consumption. Flashers aren't as easy as the stock flasher can needs the load to flash properly. Also you may be able to find some kind of LED headlight but they are not as common.

8/11/2016 8:43:25 PM

Toss that Selenium Rectifier, go to your electronics store and buy a Full Wave Bridge Rectifier, https://www.radioshack.com/collections/maker-parts-kits/products/radioshack-8a-400v-full-wave-bridge-rectifiers?variant=5717581061 Take each stator wires and solder each to each connection with the sine wave (AC) label and the + and - to the battery. The Selenium Recs. are all breaking down with age, this will fix it and will work on all 2 wire stator Hondas.

8/11/2016 12:14:37 PM

A thought on the Cl77. I had problems years ago. My stator was bad however, without any lights on the bike ran great. Make sure that the tail light and the headlight are of the proper wattage and all bulbs for that matter, the winkers, can be a drain if this unit has blinkers installed. The headlights that are out now can be too much for that original battery to maintain a charge. Also, the stator does have a separate circuit from the engine that is just for the lights, I would measure volts/amps on the lighting circuit with the engine running and lights off and then on. You should be able to measure an acceptable amp drop under a couple of amps. The stator should be able to withstand the proper lights working and engine on and keep the battery charged. Voltage at the battery lights on and engine running should be at least 13 volts. Good luck..Joe

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