M94 Lighting Lightning

[matt glascock]

Hi all, Here's the scoop. Riding home from work tonight on a stock 1972 Wombat. The speedo backlight began flickering very brightly and light intensity was rev-specific. At times it was reminiscent of a xenon strobe light. Cool, but not in this setting. Through this all, the headlight was steady, but again brighter with increasing revs. Luckily, as I pulled in to the drive, the headlight and speedo backlight decided to go completely dark. Too late to open the bucket tonight, but what would account for this and what should I be looking for so that I can streamline the repair process. The brake light still functions appropriately. As always, many thanks.

[Bill2001]

No idea off the top of my head.
BUT check this:
*What shape is the wiring & wiring harness in? New, good shape, old and patched?
*Is the wiring stock Hodaka or is it modified?
*Remember, on the WBat, the headlight works off the AC alternator with the engine running and the Emergency switch in the "AC" position. From whst you said, it sounds OK til the point where it wnt dark.
*The strobing instrument light may have been a broken filament vibrating on-off. Or a loose connection. Check that bulb.
*Othetwise, grab wiring s chematic and start tracing. Start at the alternator and work forward. I find it useful to troubleshoot with a xerox copy so I can make notes and highlight specific circuits.

[olddogs]

It has been my experience that the early Wombats had issues with voltage regulation. Seems the lighting coil goes whacky sometimes and burns out the headlight and any other bulbs it can get to. I have used the Road Toad style voltage regulator to smooth out these voltage spikes. I believe you can use the RT wiring diagram to locate the proper location in the harness. It has been discussed many times on this site. Check the archives.

They also made a bar style wire wound voltage regulator that bolted to the outside of the battery box. I had a few Wombats with this style. I think it was a quick fix add on until the small square style regulator was standard equipment on later models.

Funny how true the old expression "a light shines its brightest just before it burns out" fits the Wombat.

[matt glascock]

Thank you, gentlemen.

Bill, Stock AND original wiring harness with a few patches to bring it up to snuff after a DPO MX'd the bike and stripped lights. horn, etc. Looks like back to the schematic drawing board. Old-Dogs, the bar-style regulator is in the system now. I do have a spare Toad regulator. Maybe time for an upgrade. I'm opening the bucket now. Will report findings. Thanks again!!

Best,

Matt

PS - totally agree with the adage

[Bill2001]

This is about all you can do in a case like this-- start tracing wires and checking voltages. That old bar/resistor was a stopgap measure that dissipated the excess voltage from the alternator and kept it from crying the headlight. The "new Toad type" is a little better in that it shunts excess voltage over 9v to ground. Not sophisticated, but is still is still used by many Japanese bikes, and Ducati and Harley. If you have a Toad reg, I'd use it. Three wires, look on a Toad schematic for hook-up.

When I got my WBat 94, the main harness was crusty enough to make me build a fresh one.

[matt glascock]

Bill, the voltage regulating coil was very shabby - almost "fuzzy" looking. Both bulbs in question were burned out. Fortunately, the Toad voltage regulator was very easy to integrate into the electrical system. Happily, the Toad manual has a very well prepared wiring diagram. In the bowl, the blue common ground was soldered to the lamp holder and that joint had failed. I drilled a 1/16" hole in the lamp holder to accept the ground wire which I then resoldered in more securely. Oh happy day! It all works perfectly. Interestingly, now the red "high beam" indicator light is on continuously regardless dimmer switch position. My wheels started turning and I started trying to figure out how I could use a Dremel in the repair process of the high beam indicator but then remembered Captain Eddie had one of his operatives weld the chuck of my Dremel and take all my mandrels after I threatened to destroy my Combat clutch basket with it. . I'm leaving the high beam indicator as is and have decided to take the money and run. Great suggestion, Bill. For any of you "M94 Wombateers out there, you might consider scoring a Toad voltage regulator as a replacement upgrade to the wiring harness.