SOHC.co.uk Forums > Project Board
Honda CB750K5 Restoration by Royhall
royhall:
Thanks for that. Would the test be the same for the regulator side of a modern reg/rec that is fitted to mine. I noticed this problem because I keep all my bikes on optimisers. Usually after a run on the other bikes (all same optimisers and batteries) it takes about 10 minutes for the optimiser to run through it's thing and top out the battery. On the K5 it took over three hours to recharge after a 50 mile run pointing to failure of the charging system. As stated earlier, on jumping the field coil wire (white) from the battery it then gave a good charge at 14V, the black from ignition on gave just under full battery voltage. To my mind that provers the charging circuit and the rectifier side of the reg/rec and points to failure of the regulator side. Am I correct in this. Cheers Roy.
Bryanj:
It sounds like it to me Roy.
The black wire into reg should be within 0.5v or less of battery voltage with ignition on, i would turn kill switch off for this.
Then check again with engine running.
More than that reduction says bad connection at one or more on the many contacts between battery positive and black at reg, usually ign switch or one of the bullets.
Then try testing voltage on white wire out of reg, this should vary from low volts if battery charged to full battery volts as battery looses charge NOTE NOT 12V BUT BATTERY VOLTS
Then as you say if you jumper the white to battery pos this bypasses the reg and the battery voltage should keep going up and up-------not a good idea for extended use.
There used to be a 500 about called gentlemans rocket or something like that, i think Steve D had it for a while and the owner/builder designed his own breadboard electronic reg and posted the diagram which i did have but its gone in one of the many puter crashes over the years.
Hope that helps
royhall:
Thanks Bryan. With ignition on and kill switch off it is 0.4 V lower than the battery at the black wire. With ignition on the white wire is putting out 0.22V. Does that sound right. Battery is a fully charged AGM.
Bryanj:
If the voltage on white wire goes up as the battery discharges then yes all is ok BUT i suspect that the white wire voltage will stay low which means the regulator part has failed
royhall:
Yes I agree. Unfortunately I need a discharged battery to test that, I shall ask around. Failing that I have a spare battery that I can stick a bulb on until it drops below 12v.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version