Are you having electrical system problems? Bike is not charging the battery while riding? Battery light coming on causing the check engine light to come one? I recently had this issue. While riding, the battery light would illuminate and the battery gauge would start falling. After a few minutes, the check engine light would illuminate. Seemingly, at random, the lights would turn off and the battery gauge would return to normal readings. This continued until one day the bike simply left me on the side of the road. The battery gauge had dropped so far down that it was reading 0 volts, the radio wouldn't turn on and none of the lights would work. I ended up having to replace the stator. Below are some troubleshooting steps that you can follow to check the most common items that could have failed causing the problems.
The first thing to check if you suspect a charging problem is the battery and the wires attached to it. If the wires are loose, make sure to tighten them up. If you see any corrosion, disconnect them and clean them off with a wire brush before re-attaching. Check each cell on the motorcycle battery to make sure the electrolyte is covering the plates, if not, carefully add distilled water until the fluid reaches the "top" line on the side of the battery. If your battery is less than fully charged, use a low amperage charger (1 to 3 amps) and charge it until the indicator says it's full. If it doesn't take a full charge, replace it with a new one. When your wires are clean and secure and the battery fully charged, you can get started checking the system. Perform the following checks: Battery: Turn ohmeter to the DC Volts setting that can read 12V or more. With your motorcycle off, read from Positive to Negative making sure the Red is +, Black is -- If battery is good you should get about 12.5 to 13.5 volts Charging: Using same multimeter range, start the motorcycle and run RPM's up to above idle. Voltage should increase to several volts above initial reading, usually to about 14.7 V Voltage should not go much higher than 14.7 V. If voltage goes a lot higher when you rev the engine, you could be overcharging due to a voltage regulator problem. If voltage doesn't change, your motorcycle is not charging. Stator: If your motorcycle is not charging, you need to check the stator. Locate the plug for the stator on the front of the engine block. Switch the multimeter to OHMS range on the lowest setting, usually 10 ohms. With the motorcycle off, read between the 2 pins or holes in the block. These should show continuity. If your meter is accurate you could read 1 to 3 ohms, but cheaper meters will not be that accurate. As long there is continuity it passes this test. Now change the setting on the multimeter to the highest OHM range like 100K. Touch one probe to a pin or hole in the engine, the other to the engine case or a metal bolt on the engine. The meter should not move. Try the other pin the same way and it also shouldn't move. If you get any reading the stator is shorted and must be replaced. This requires special tools and you should consider taking it to a shop. If you get no movement on the meter, it's not shorted out so you need to check for output. To check for output, change multimeter to AC Volts setting over 100 Volts. With the alternator plug disconnected, start the bike. Use the probes (not polarity sensitive) to read between the pins or holes in the engine block. You should read about 20V per 1000 rpm's. At idle expect about 25V, as you rev the engine it will increase to 60 or 70 Volts. If it does your stator is OK, if you get no output the stator is bad and you will need to replace it or take it to a shop. Voltage Regulator: If your stator is not shorted to ground and has the proper output, your regulator is most likely the culprit. If your stator checks out OK but battery voltage doesn't increase when the motorcycle is running, the regulator isn't doing its job and needs to be replaced. It's an easy swap, just make sure you bring the old one with you to make sure they give you the correct unit. If the battery voltage goes too high when you rev the motorcycle the regulator isn't limiting the voltage and again it needs replacement.