Probably an hour into the attempt at grafting a good used dimmer switch wiring harness into the existing switch housing, it appeared that this was an effort destined to fail. A new(er) lesson with vintage Honda parts and pieces is that the dimmer and starter handlebar switches are NOT all the same, beyond the length of their harnesses to match the model application.
It has been noticed on more than one occasion, that ordering vintage Honda dimmer switches from similar applications other than the 250-305s have been noticeably different in subtle dimensions of the components. A rare turn signal switch for a CB72-77 coming from Asian eBay sellers arrived with male terminal ends which were, perhaps, a .5mm smaller than those normally seen on the bigger twin applications.
In the case of this current Dream project, the switch housing was slightly smaller than normal and the width of the dimmer contact plate was narrower, as well. Trimming the contact plate width was partially successful; however the starter button wiring was also in need of repairs due to exposed wire just behind the button plate. Well into the second hour of watch making exercises, the repair of the switch assembly was abandoned and the whole switch replaced with the one remaining a/m dimmer switch left in the box. This change lead to more frustrations as the wiring colors were not exactly the same as the OEM Honda parts, but seemed to make sense when connected; black to black, orange to red, blue to blue and green to green. When tested, there was only power going to the high beam circuit. Removing the switch again revealed that the central power feed to the switch was BLUE instead of the normal GREEN wire colors. Once that was swapped around, the low beam wiring was activated okay, but the light would not illuminate… the low beam bulb filament was burned out!
Another problem was that the starter button wasn’t functioning properly. That side switch was removed and inspected with more repairing to do on the contact plate wire. Once the wire connection was repaired and the switch reassembled, turning the key up to the LIGHTING stop of the ignition switch activated the starter motor! Unplugging the starter button wire in the headlight shell stopped the live circuit and the whole switch was removed from the handlebars, except for the throttle cable. When the switch was checked again, the new repair suffered a pinched wire as the retainer plate was installed, causing a short to ground. The pinched wire section was insulated and reassembled only to find that the starter motor was still being activated, even with the switch completely removed from the handlebars and would only stop when the wire was disconnected once again. Apparently the grounded wire was backtracking through the throttle cable housing to complete the circuit.
This time the starter button spring and guide plate were found to be interfering with each other and when a very slight adjustment was made on the plate, the ground path stopped being available to the starter motor. FINALLY the switch was reinstalled and the starter button working normally once again. The starter motor isn’t turning the engine over due to the removed springs/rollers/caps of the starter clutch. New springs are ordered and headed this way from the snowy mid-west this week.
Numerous potential ground/shorts were repaired in the headlight shell wiring, which caused several of the mini-fuse links to pop when the handlebar switches were not functioning properly. Yes, a main fuse was installed into the battery terminal wiring to protect the rest of the bike’s wiring circuits. With each passing hour, the bike became electrically more and more reliable and safe. The ignition timing was checked and found to be spot-on, so the next step was to fire the bike up again, after the carburetor had been checked and a new gasket installed.
Someone, somehow, had fitted a square bowl carburetor gasket into the round bowl carburetor body previously. An ominous sign when removing the carburetor was that a fresh brass SAE fuel fitting was screwed into the carburetor body. I had never thought to check the thread pitches and diameters of the OEM metric parts and SAE replacements, but apparently they were close. Sarah had mentioned having problems with fuel leaks at the petcock/carburetor when the bike was picked up and here was the most likely source for one. Even with the tapered threads of the new fitting, there was a little drip at the fitting/body interface. Tightening it further didn’t make it stop, so the fitting was removed and sealed with Teflon tape, which did finally cause the leak to cease.
With a leak-proof carburetor fitting, the bike fired back up with full choke (now repaired) and settled down to idle fairly quickly. The engine was noticeably quieter overall, now that the camchain had been adjusted, but there is still a bit of an unsettling rumble at idle. A quick trip around the neighborhood was successful, as long as it was shifted correctly (rotary gearbox pattern).
The front brake was another cause for concern and it looked like the brake arm might be registered off one spline. Once the cable was removed from the brake arm, it seemed obvious that there must be a lot of wear in the brake shoes as the arm moved quite a long way before the shoes were contacting the brake drum. Once repositioned, the brake arm cable adjuster was just catching a few threads on the cable end, but it will probably not affect braking in a positive manner. New brake shoes need to go on the parts list, along with a new rear chain and sprocket set.
As you can see, once you get started into one of these rehab/revival projects, it is easy to wind up going “down the rabbit hole” into a whole new world of repair challenges.