QuestionAbout a week or so ago I emailed you with a question on my motorcycle, which I recently purchased, not charging properly. When I start it, it starts with about 12.5 volts of charge and reduces to about 11.25 volts after it gets hot. You suggested checking the stator connectors for overheating. I checked the connectors and found they have been hard wired, but the wires get very hot after the motorcycle has run for a while.
Before I put out a chunk of money for a stator and the connector repair kit, could the rectifier/regulator be the problem. If so, how can I check the regulator/rectifier.
Thanks,
Tom Selfridge
AnswerHi Tom,
If the stator's multi-connector has been eliminated and the wires soldered together, indicates prior charging problems or prevention techniques. You'll have to separate the wires to perform the following tests.
Most charging system problems can be diagnosed by the average owner if you have access to a multimeter and an ammeter. The ammeter should have a scale of 0-5 amps and the multimeter set to the 0- 20 VDC (or similar) scale. Connect the multimeter across the terminals of the battery. Disconnect the positive lead on the battery and reconnect it through the ammeter. With a warmed up engine running at 3000 RPM, headlight on high beam, fan motor off, and a fully charged battery, the multimeter should indicate 14.5 volts and the ammeter should show 3 amps.
Stator testing:
Disconnect the alternator main lead at the block connector. With the multimeter set to measure resistance (ohms) check the continuity between all three of the yellow leads coming from the stator. If there is a lack of continuity between any two of the leads - the stator has an open coil and must be replaced. Also check the continuity between each yellow lead and ground. If continuity exists on any of the leads to ground the stator has a shorted coil and must be replaced. The engine must be removed from the frame to facilitate removal of the rear engine cover to gain access to the stator.
Regulator/Rectifier testing:
With a warmed up engine operating as outlined in the first test, increase engine speed to 5000 RPM. The voltage should never increase above 15 VDC. If it does, the regulator is malfunctioning. Trace the leads from the finned rectifier unit to the 8-pin connector and separate the connector. Check the resistance between the green and each of the 3 yellow leads. In the normal direction of current flow the diodes tested in this manner should offer little resistance, the precise figure being 5-40 ohms. If the test probes are reversed, a very high resistance reading should be obtained (approx 6K ohms). Repeat the same test between the red/white lead and each yellow lead in turn to check the negative diode trio in the rectifier unit. The same readings should be obtained. If any of these six tests show readings not as outlined here, the rectifier is defective and must be replaced. The regulator/rectifier is a combined unit and for all practical purposes is unserviceable.
