Ixion
6th June 2010, 17:58
OK. Phoebe's charging system has always been crap. It was crap from new but mine has always been crappier than standard crap.
But on the last ride to Puhoi, it died completely. By the NW motorway when I tried turning the headlamp on all I got was a faint yellow glimmer. Luckily I got home before dark.
Now, a bit of necessary background: it's magneto ignition, doesn't need a battery at all to run. And kickstart only . So the charging system is only for indicators, headlamp and brake light. The system itself is dead simple. Two coils in the flywheel magneto. One permanently in circuit to the rec reg (shunt regulator), one switched in by the headlamp switch.
When I got back home I checked and found the headlamp switched coil was producing something, but the "always in circuit" one wasn't.
Pulled the flywheel off, and found that the little cardboard former thingy the coil is wound on had disintegrated (age, oil, vibration). And the coil itself was sliding on the metal gizmo, and the wire had worn through. But luckily it was an outside winding, so I was able to resolder it OK. Only lost one turn.
Tested resistance, more or less as per book (allowing for vagaries of measuring less than 1 ohm ). More significantly, both coils measure the same . Wodge up the coil with ice cream sticks and araldite in the approved Bodger and Bashit fashion.
Reassemble, and test. OK. Coil A I have 0.4 amp at idle, rising to 0.8 roughly at road revs. Coil B, the same. Both in circuit, I have about 0.7 amp at idle, and 1.5 amp at road speed. Until I switch the lights on, when it goes to a 2 amp discharge.
Arithmetically that all adds up. The two coils are producing exactly the same current. The headlamp has a 36 watt dip beam (should be 24/36 but you can't get them). With a 6 watt taillamp, that's just about exactly what I'm seeing.
So, both coils the same , unlikely both would be exactly the same dodgy (the B coil is newish, also). But I just don't have enough amps.
Where have the little bastards gone?
Only two things I can think of.
One is a dud rectifier, one diode gone allowing half rate charge. I can test that I think by substitution. Somewhere in the shed (famous last words) I have a stock of full wave rectifiers.I think. That would be an easy win.
Or, the magneto flywheel isn't magnetic enough. And I have no idea at all how to test that . A screwdriver sticks to it, that's all I can say. And if it is feek and weeble, how do I get more magic smoke put into it?
Anyone have any ideas ?
But on the last ride to Puhoi, it died completely. By the NW motorway when I tried turning the headlamp on all I got was a faint yellow glimmer. Luckily I got home before dark.
Now, a bit of necessary background: it's magneto ignition, doesn't need a battery at all to run. And kickstart only . So the charging system is only for indicators, headlamp and brake light. The system itself is dead simple. Two coils in the flywheel magneto. One permanently in circuit to the rec reg (shunt regulator), one switched in by the headlamp switch.
When I got back home I checked and found the headlamp switched coil was producing something, but the "always in circuit" one wasn't.
Pulled the flywheel off, and found that the little cardboard former thingy the coil is wound on had disintegrated (age, oil, vibration). And the coil itself was sliding on the metal gizmo, and the wire had worn through. But luckily it was an outside winding, so I was able to resolder it OK. Only lost one turn.
Tested resistance, more or less as per book (allowing for vagaries of measuring less than 1 ohm ). More significantly, both coils measure the same . Wodge up the coil with ice cream sticks and araldite in the approved Bodger and Bashit fashion.
Reassemble, and test. OK. Coil A I have 0.4 amp at idle, rising to 0.8 roughly at road revs. Coil B, the same. Both in circuit, I have about 0.7 amp at idle, and 1.5 amp at road speed. Until I switch the lights on, when it goes to a 2 amp discharge.
Arithmetically that all adds up. The two coils are producing exactly the same current. The headlamp has a 36 watt dip beam (should be 24/36 but you can't get them). With a 6 watt taillamp, that's just about exactly what I'm seeing.
So, both coils the same , unlikely both would be exactly the same dodgy (the B coil is newish, also). But I just don't have enough amps.
Where have the little bastards gone?
Only two things I can think of.
One is a dud rectifier, one diode gone allowing half rate charge. I can test that I think by substitution. Somewhere in the shed (famous last words) I have a stock of full wave rectifiers.I think. That would be an easy win.
Or, the magneto flywheel isn't magnetic enough. And I have no idea at all how to test that . A screwdriver sticks to it, that's all I can say. And if it is feek and weeble, how do I get more magic smoke put into it?
Anyone have any ideas ?