QuestionHi Terry,
This one is driving me and my son crazy! We strap a multimeter to the gas tank and monitor the voltage at the battery while we drive. At first all is well - holding very steady at about 14.3 Volts - then after about 10 minutes or so the voltage starts climbing and keeps going up over the next several minutes to finally over 17 Volts!! Yikes!
We replaced the R/R and exactly the same thing happened. We of course checked the rotor resistance and found about 4.5 ohms cold.
It seems to us that this is HEAT related - as the bike gets hot, the voltage regulator loses control of its ability to hold the voltage output constant at 14.3 (or so) volts.
Could the rotor be getting hot and shorting out and could that cause this type of symptom??
We first noticed the problem when the water in the battery kept going down rapidly (from the overcharging). At the same time we replaced the regulator/rectifier, we also replaced the battery with a Yuasa brand to rule out a bad battery too.
We're stumped and ready to just buy a new rotor too (we've heard they're trouble prone), but before we spend another $100 swapping parts, we thought we'd ask you what you think could be causing this runaway voltage issue!
We'd appreciate any thoughts you might have on what we should look for next...
Thank you for your help,
Chuck C
AnswerHi Chuck,
It sounds like you have a tough one here, spending unnecessarily is usually not our plan either. You may want to go at it in another manner here it seems to me. Have you noticed any ignition differences, this will help with the alternator elimination. If the bike runs the same after 10 min it may not be the field coils. To isolate them you need to measure the ac voltage before it goes into the rectifier/regulator. If it goes up in 10 min or so then that's the problem. The proper wiring diagram should identify the ac voltage wires, measure between the phases here. (It may be 3 phase) Be careful not to short anything!
Regards,
Terry.
