To help the voltage regulator and the entire charging system, an easy and inexpensive upgrade is to replace old, small, worn and sometimes corroded stock BMW wires with a set of upgraded heavier wires you make yourself. Here's how: The Best Wire to Use For the best wire, go to a marine supply store and look at their selection of bulk wire. They will have wire as thin as 22 gage and as thick as 6 gage, with costs ranging from $.11 to $.49 per foot. The marine wire is rated for 600 volts, is oil-water-gasoline resistant, and is made with very fine multiple strand wire. The finer the wire used in the multi-strand wire, the more flexible the wire will be to handle and install, which is important when working within the tight confines of a motorcycle. If you can't find a marine supply store, auto parts and hardware stores also carry quality multi-strand wire at reasonable prices. I have used this material in the past and it works well but is not as flexible as the marine grade wire.