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Discussion Starter #1
Just finishing up a light resto on this 68 CL450. When I got it was barely producing 12.1 volts at RPM. During the resto I ditched the original rectifier and regulator for a modern combined unit. 35 watt halogen headlamp . Connected the white and yellow wires from the harness going to the headlight switch to get max charge.
Testing yesterday with bike running harness unplugged testing AC current across the yellow and pink wires
19-20 VAC at Idle
38-40 VAC at 3000 RPM.
Reconnected harness , now testing DC current at the battery
12.5 before start
12.85 @ Idle
13.10 @4000 RPM
With the headlamp on it seems to drop off pretty good, wondering if it would even charge.
I'm guessing bad Stator or Rotor ?
Thanks for any suggestions
 

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Sensei
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Rotor and stator are showing as good based the AC outputs......IF neither yellow or white wires (separated by unplugging at alternator plug) show continuity to chassis ground......
(although unplugged AC output @ 6K would be good to know as well)......
Assuming all good above (no continuity to ground and continuing rising ACV), I'd suspect faulty main harness to rect/reg connections/wiring OR a bad /weak Battery........Phone for in depth discussion.......
 

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Discussion Starter #3
Tested yellow and white wires for continuity at the unplugged Alt. plug and show no continuity to ground. Brand new Moto Batt AGM battery, will do a running AC output test today up to 6k and see what we get. Also yesterday worked on cleaning up connections in the alternator plug and the Rectifier reg plugs to assure we have good connections.
Thanks again for the assistance, glad to hear that you don't suspect the Stator or Rotor.
 

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Discussion Starter #4
So ran some running tests today.
ACV across the yellow and pink wires, connecter unplugged,
Idle- 20.9
3000 rpm- 42.6
6000 rpm - 76.8

DC @ battery 13.05
Idle after start up- 13.00
3000 rpm 13.70
All seemed acceptable.
Turn the low beam head light on and it sinks and sinks even @ 3000 rpm.
????
 

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Well, the AC voltage seems good and you said you've replaced the stock rectifier and regulator with a modern combo unit. When you think about how you ride these bikes, you'll not likely be at 3000 rpm very long and certainly while on the road at any highway speed, you'll be above 3000 virtually all the time except at stops... so I'm not sure there's anything really wrong with it. When you say "it sinks and sinks" at 3000, just how far?
 

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Sensei
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Your alternator is fine.... BUT..... ANY battery That takes and holds voltage, but won't deliver amperage is either discharged, undersized (amperage rating), or defective..........13+ volts means nothing if it fails under load.......
The nearest auto-parts store will probably load test it for free....... NEW DOES NOT MEAN GOOD......And about 15 % of the new batteries I get are faulty out of the box........
 

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I've had success with my Common Motor Collective combo unit they sell. Without it and using my previous voltage regulator I was getting 15.5 VDC. Burned out headlamps quickly and they're expensive for the 1973 CL450K6. Battery cell electrolyte level dropped quickly. The CMC one works well, 13.8 VDC never higher. Mounting holes were too far apart for setting below the crossover air tube so filed those holes out a bit. I was surprised as it came with 5 wires, not 4. The fifth, being black, ties in with 12 VDC so it can sense the DC bus voltage.
 

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"12.5 before start"
I am thinking your battery might be on its way out.

Charge it full and then let it sit for 30 minutes or more then test the voltage again. Anything below 12.6V is suspect IMO/IME.
 
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