Motorcycle electrical systems are more exposed to the elements than cars so it’s important to keep the system sealed against water infusion to avoid corrosion of the electrical connections.
In particular, the electrical connection between the alternator and the regulator carries a very high current, so corrosion there will lead to overheating the connector and adjacent wiring. I recommend eliminating this connector entirely using solder and shrink-tube insulation.
Another problem area is the rubber boot on the electrical connection to the starter motor. It leaks, collects water and corrodes the connection. Here, you need to clean the connection and then seal it watertight with silicon sealant.
Every instrumentation, power and ground connection on the bike is a potential problem. So the best approach is to prevent water from reaching the connections whenever possible and to reduce electrical resistance at each connection.
Care should be taken to avoid forcing water into the connections so set your wash hose nozzle on spray (not stream) and avoid using the high pressure commercial wash/steam systems on your bike.
The connectors are designed to be waterproof, but over time seals will harden and eventually moisture will get in. Some owners make it a practice to using dielectric (non-conducting) grease to keep water out of connectors that don’t get hot enough to cause the grease to liquify.
For connectors that stay cool enough to let the dialectric grease to remain thick, use it to seal the male-female seam so as to prevent water from entering the connector. I'd avoid putting it on the connecting pins themselves. Use in connectors that get hot runs the risk of the grease liquifying and getting on the pin surfaces.
Using dielectric grease on connector pins can be a source of unwanted high resistance. Ferrari used to put dielectric grease inside all of their engine connectors (that will see water) but they eventually found out that it caused problems. They issued a service bulletin that advised cleaning out all of the grease and to use instead a contact enhancing product called Stabilant 22.
http://www.stabilant.com/appnt20h.htm
When applied to an electrical connection Stabilant 22 becomes conductive. The manufacturer claims that it is as good as a soldered joint.
VW, Porsche, BMW and Ferrari all recommend the use of Stabilant 22 on electrical connectors. You can buy it at your local VW parts department. Don't be shocked at the price, a 5ml tube is around $40.
A 15 ml bottle of Stabilant 22 costs $61 a NAPA stores. It's packaged under NAPA's Echlin brand, so when specifying the part number the "line" is ECH and the part number is CE1.
There are some other specialty products that try to address the connector protectant issue. Deoxit for example:
http://shopping.netledger.com/s.nl/...T113328/category.94/it.A/id.1610/.f;jsessionid=fcea1546a36c408db100f4c50d0dcc64
Another is Boeshield T-9
Finally, WD-40 has no place in electrical connectors or components. WD-40 is composed of 80% Stoddard Solvent (that is similar to paraffin), 20% light lubricating oil, and a bit of fragrance. So, I advise against using WD-40 in any part of an electrical system because it leaves an oil residue. Use an electrical contact cleaner instead is to remove any grease and oil that is causing conductivity problems. Sticky relays should just be replaced because in the long run they’ll probably fail when you least want them to.
On a wet bike that won’t start, I recommend first using a leaf blower to dry everything out and let it sit in the sun for awhile. It'll start eventually. Then waterproof it.
