1967 CL90.... same engine as the CT bikes of that era, ranging from 90-125cc. The honda four speed, 6-VOLT, SOHC small engine. You all know them.

This bike has started showing up an issue, where it would suddenly die, usually at idle but then at any RPM, it would simply die, and not start up again, completely dead and no spark or anything.

I checked the main fuse of course, then went over the entire wiring harness and all connections and made sure there are no breaks or shorts anywhere.

I put the battery on a trickle charger to make sure it was full, on the off-chance that this was a charging issue. Now, with the old selenium regulators on these 6-volt bikes they say you must disconnect the battery from the bike before you hook it up to a charger so you don't cook the rectifier. This is annoying on the CL because the battery access plate is bolted on and, frankly, I'm lazy and it's a hassle. So I made a modification from stock. i installed a three-way toggle switch on the negative lead. One toggle position connects the bike electrical just like normal, the middle position disconnects entirely, and a third connects the negative battery lead to a wiring harness, which the trickle charger would hook up to for battery tending.

I have not tested or used this system yet, i have not hooked up the charger. I mention it because once i installed this toggle and had a quick way to connect/disconnect the battery it inadvertently led me onto a clue.

During the times when the bike dies (which is now sporadically, anywhere from 0 to 5 to 30 seconds of startup and idle time) I cannot get it to start back up with the battery connected. No spark at all. However, flipping the toggle to diconnect the battery quickly remedies the problem. It starts right up, and runs. The voltage readings show the current with battery disconnected is very high, about 12 at idle, and if i turn the idle screw for another 100 rpm I get another volt. i haven't revved it in this configuration to avoid damaging anything, and i haven't run it more than 3 seconds at a time in this configuration.

I cannot remember the correct method to test the rectifier, but it has 4 wires and I tested them all for continuity (ohm reading), in both directions (positive/negative and reversed) and I get infinite resistance between any and all terminals in any direction. No current can get through the rectifier.

NOW.... does anyone have any insight to the problem? Would a replacement rectifier be the solution? Am i overlooking anything else?

Also, does anyone know if these bike rectifiers are also regulators, or do they rely on the battery to regulate? I cannot seem to find any info for this question online and the guys at the honda shop don't know anything about anything that's not currently on the showroom floor. the honda wiring schematics label the component as a rectifier, not as a regulator/rectifier. I'm curious as to whether the high voltage readings were associated with the battery disconnected or a faulty regulator (if there is such a component or integral function to the rectifier)

ONE MORE THING: I can always start up the bike in 'battery disconnected' toggle position. I can usually then switch it over to 'battery connected' and it will continue to idle for an unreliable number of seconds but not usually longer than a minute. If I rev the engine, that usually causes a shut-down. I don't know if this helps support any theories or complicates them. I'm hoping the former.