I'm currently build a CA95 with 6V electronics and would like to convert the system to 12 Volts for better aftermarket selection (this is a custom build).
I've been doing some research on how this conversion has been done on other vintage 6V machines yet haven't found any info for this specific bike/engine.
It appears I'll need to change the voltage regulator to something like the DVR2 specified in this article: http://matchlessclueless.com/electrical ... onversion/
And then of course change all the exterior lighting, fuses, and components to run off of the new 12V system.
My question is are there any modifications that would need to be done to the alternator in order to switch to a 12V system? Or changes to any other internal engine components like the points system? A change to the wiring from these systems? I'm sending the engine out to be rebuilt asap and would like to make any necessary changes while it's being rebuilt.
Any help is much appreciated!
Thanks,
Dave
Converting to 12V Electronics
Dave, you won't need any wiring changes, particularly regarding the sizing; a 12V system requires half the current-carrying capability over a 6V system, therefore the CA95's wiring harness will be more than adequate.
Parts that will require replacement:
These systems don't employ a regulator; charge regulation is achieved by loss within the rectifier diodes and via load-balancing within the entire system. The ignition system's condenser should fall within the scope of coping with 12 volts. Fuses aren't really voltage-dependent; their insulation properties tend to be though, but not in this case. Some fuses are rated for safe use at certain voltages, ie: >32V, >48V, >250V, etc, etc. These Hondas are usually protected by way of a 15-Amp glass fuse. Here's a link to my Mediafire archived Shop Manual covering your bike. Steve,
Thanks for all that info. That's great. Considering the alternator and starter have pretty specific fitments, how would I go about finding 12V replacements that "bolt up?" From what I've been reading elsewhere, the internal systems are usually capable of producing enough power to support the 12V system (once all your external components are switched over) but the alternator (here's where I'm hazy on understanding) only produces single phase power instead of three phase, therefor it will take longer to charge the battery. Is any of that making sense? Also, and this is obviously a work around, say I wasn't able to find a 12V starter replacement - could you run an inline diode(?) that drops the voltage to 6 volt just for that component?
Perhaps something of a tall order, here... I forgot to add the horn to the list of replacements! Not really, as the wiring diagram shows the alternator coils' arrangement as being identical to those of the 12V type. The 6V coils' impedances will be doubled ohms readings. You'd need to get the AC output voltages measured and compared to a 12V bike's. No damage to the alternator would be sustained by upping the battery voltage, as the rectifier comprises four diodes which block any DC from reaching the coils. You could, perhaps, run the starter motor via a 6V/100-Amp Zener diode; but you'd need to find a suitable location to mount it on a heat sink that us electrically isolated from the bike's grounding. It's 42 years since I laid eyes upon my last C95, so I can't remember if the starter motor is similar in physical size and mechanical mounting to that of a C72/77. You could possibly get the starter field & armature coils rewound to 12V spec..... Steve,
Again thanks for all the help. So was your initial reason for stating the alternator should be replaced due to the output voltage possibly being halved/too low? If you haven't guessed yet, my electrical knowledge is limited. But I recall from charge testing on other 12V systems that around 14.5V is what you're looking for at the battery terminals during engine operation with the revs up a bit. This signifies a good charging system. I'm assuming this voltage regulation from the 30-45V alternator output (reading from 12V C77) down to 14.5V at the battery is done by the regulator. So in theory, if the CA95 alternator puts out 14.5 Volts would that then be enough for adequate battery charge at running sequence? I'm still searching for alternator output voltage from a CA95...since mine doesn't run.
My opening gambit on the parts that would require replacement was based on theoretical rather than practical experience surrounding the proposed task. What we need to determine is the pre-rectifier AC voltage available at circa 3000rpm before any firm judgement can be contemplated.
The AC output is based around the stator coils' windings' impedances (resistance readings), the magnetic strength of the rotor and the air gap between those coils and the rotor. All theoretical at this stage; empirical data is essential. If your (correct) assumption proves to be the case, ie 30-45VAC, then I'd say that you'd more than likely be on the road to success. Once again, remember, there is no regulator. The old selenium rectifier's loss was sufficient to regulate the DC voltage. If the aforementioned ACV readings are attainable, then just replacing the rectifier with a modern device should tick the box.
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