After having to short my starter solenoid several times in only a few weeks of driving, I decided to do something about the weak stock solenoid. It would frequently fail to engage in cold weather, or after a short cranking of the engine, it would not re-engage. Yes, a new battery would mostly fix it, but mine is only a year old, and really - the solenoid should give power to the starter until the battery is to low to turn the starter.:lash:
I was thinking of putting in a car solenoid, but it wasn't going to be pretty. Remembering some high school physics that thicker wire or more wire makes a stronger magnet, I thought I would try rewinding the solenoid coil.
Taking apart the solenoid, you have to unsolder the coil wires before splitting the top off. The steel case is crimped around the edges holding the coil with a steel cover in place. I drilled a close fitting hole in a block of wood to hold the steel cup in the vice and then used a punch to hammer the crimping back - it was very easy to do.
I stripped the old coil, which came out to about 490 turns of 26 gauge (I think - measured over the insulation). I lost count winding the new wire, but I was putting as much as I could fit anyways. The wire is wound around a plastic piece much like a sewing machine bobbin - but larger. I stuck this over a tapered shaft (long punch), and put the shaft in a lathe in it's lowest speed. A variable speed drill would work if you had an extra set of hands. I had a spool of 24 gauge (I think!) and wound on a little extra. I had to take off most of the extra, or the coil would not fit back into the steel cup. If you do this, make sure the coil goes all the way back to the bottom of the cup before crimping it back in place! I would guestimate that the new coil took a little over 100'.
The whole project took only 2 hours start to finish, and the results work great. I can crank the starter more than I care to, and the solenoid doesn't give up. Wish I would have done this a couple years ago.
The contacts were fine, but I had cleaned them 2 years ago when I first started having the problem (had the bike for 3 years now). The solenoid is just way too weak to be reliable, as soon as the temperature gets a little low, or the battery has already cranked the engine over - I would just get a tick when hitting the starter. Not the typical Click of a car solenoid. Wired in a car solenoid to see if it was the wiring - nice solid Click. So pretty happy I tried this - it really was not a big job.