O.K. here goes. I have been having mucho problem with my 93 650L and an intermittent spark problem that has caused me to do way too much research and learn way more than any mere weekend rider should about 650L Electrical. First off I will not give you a big rundown on electrical but just a few suggestions on where to look for your answer and what in my opinion could be causing it. The 650L has a 3 phase stator that puts out just over 190Watts so it is a pretty well maxed out stator. There are 3 lines (yellow) that run into the rectifier that are A/C current. Each line should be putting out in excess of 50 Volts. The Rectifier turns the A/C into D/C for your battery and runs it through the red wire into the battery for charging. The green wire is the ground. Inside the rectifier are six diodes that allow the passage of electricity in only one direction, regulate the voltage down to 14-15V useable, and turn the current into what is known as dirty D/C. The battery fills in the sinewave which makes it clean, but I am not an electrical engineer and anyone who is, feel free to better explain it or tell me I am full of sh...... Apparently the rectifier becomes very hot as the excess input electricity is dissipated as heat out through the rectifier heat sink/fins. Don't ask me to explain detailed theory here but you should check out the Electrosport website, you can find them through a google search. They are a company that makes stators and rectifiers at a great price. They have a detailed explanation on how to check your rectifier with a multi-tester in addition to, if you call them on the phone, they will talk with you forever and ask nothing in return. Very good people. You might want to call RickyStator.com also. He was the same, very helpful, spent a bunch of time and asked nothing in return. I would highly recommend both. I am finding the 650L is a lot of fun to work on and this electrical thing has me hooked. If it just wasn't for the parts being so expensive. The 650L has a stator, rectifier, CDI unit, pulser, ignition coil, and three safety switches in addition to the on/off run switch and keyed ignition. Trying to find an intermittent spark is harder than trying to find a lost kid at Disneyland. I don't know if this helps at all but it might get you pointed in the right direction. I have read that a lot of times an electrical failure of one componet is the result of a malfunctioning other and many more are to come if you don't get to the root of the problem. Another interesting read was the "Stator Papers" on a Suzuki
GS website. It is a 5 part series on stators that was very informative. Do a search for the Stator Papers. If you have any other questions you can PM me. I am learning a whole lot about the testing process for this bike. Oh as for the cause, it could be a failing rectifier, a bad connection that won't allow the current to reach your battery, a bad battery that won't take a charge, and probably a multitude of other things I can't say. Wish I knew more, I am learning and if I find out I will let you know.