Motorcycle Repair/Honda CA95 6-Volt to 12-Volt Conversion
I've just kicked off a 1959 Honda CA95 build. I pulled the bike out of a barn with 78 miles on the odometer. I'll be rebuilding it and would like to upgrade the charging system from 6V to 12V for better lighting options.
The bike is far from running and I'm having trouble finding the electrical information needed to figure out if this conversion is possible / what is required.
There are still a lot of hurdles I'm trying to figure out having to do with the starter, points, and the "dynamo that regulates voltage automatically" - read here in the manual: http://www.honda305.com/upload/h305_forum/ca95_133.jpg
Any help and guidance would be greatly appreciated. I'm pretty new to modifying charging systems.
Dave, if the bike really is a 1959 model, it would be quite rare, as that was the first year of the bikes in the US. Honda did bring in a CA92 125cc version in 1959 that had a distributor cap on the head for delegating spark delivery. Your serial number would either have a 59 in the middle of the frame number or a CA95-9xxxxx code if it was a genuine 1959 edition. The first digit after CA95- is the year of manufacture up until 1965.
Unfortunately there is no precedent for "conversion" of the Benly charging and electrical system from 6 to 12 volts, that I am aware of. It would have been a little more feasible if you were starting with a CA160, as there is a 12v stator/rotor combo that can be used from the CB/CL160s, which do have 12v systems. The points are on the cylinder head for the 160s, not down on the crankshaft where the C/CA95 models reside, so parts are probably not generally going to be interchangeable. There may be some solid-state reg/rectifiers for 6v systems that would improve the stock charging system, or similar types for 12v. Generally, the stator must be rewound to increase voltage outputs.
You can use a cheap Radio Shack bridge rectifier instead of the fragile OEM selenium type and rectifiers don't care about the change from 6 to 12v. The battery acts as a load/storage for the charging system, so there is no "regulation" of the power output using a separate regulator unit. It was all carefully designed to work as manufactured, once you start trying to re-engineer things, you wind up in uncharted territory with these models.
The starter motor from a CB160 may or may not be worthy of modifying to fit the field coils and armature into a CA95 case. I don't know if anyone has ever tried this before, actually.
The other big stumbling block is the headlight, which is specific for the Benly models. The US bikes all have 6v sealed beam units, but domestic and Euro versions had replaceable headlight bulbs and you could install a 12v unit from a domestic Dream or CB77 into the reflector, if you track down all the matching parts. There are two bulb base types, so the reflector, socket and bulb types all have to match. The size of the reflector is also going to be a factor in how much more light you can really expect to get from 12v conversion. The Benly headlight is a good inch smaller in size than that of the Dreams, so you can't just swap in something from the 250-305 series models. The whole front end... forks, fender, headlight/shell, handlebars is somewhat of a 7/8ths scale CA77 Dream and nothing interchanges between the two.
You would have to use a CA77 double-lead 12v coil or something similar, but points and condenser are probably not affected by the voltage increase. 12v tail light and instrument light bulbs are all available from Honda or auto parts stores.
You will have to research what kind of 12v battery will fit into the tray of the Benly, too. They use a somewhat tall, thin, long battery size that isn't common.
Wiring diagrams for C95 (has turn signals) or CA95s are available at http://oldmanhonda.com/MC/WiringDiagrams/MCwiring.php#class
IF you are successful, it is going to be a "one off" achievement, I'm sure.