When I try to start my ST4, all I get is the clicking of the Selanoid. Can any of you folks out there guide me in the right direction to look for a solution. It was working fine, then after a run of 50 miles to problem occured. I hope its something simple.
You can also try applying the +12V right to the starter lug, using a big jumper cable. Just momentary to see if the starter is good. Watch out though, lots o' current (i.e. sparks), and make sure the bike is in NEUTRAL!
Like the others say, check your battery. The ST's are hard on batteries and eat them regularly. I just recently had to replace mine. The symptoms were that it would turn over sometimes normally then the next time it would barely turn over. The lights would dim way down. On the ST4s if the battery goes below 10V the bike will not start.
Many times the starter relay does not make make a good connection when the starter button is pushed. By that I mean the resistance starts to increase and you get a voltage loss through the relay, and the voltage the starter acutally sees is hardly enough for it to turn over. This started happening on my 916 with a fully charged battery. Then, yesterday, at a the end of the track day, the relay stuck and would not shut off, so I had to disconnect the battery leads. This same thing happened on my ST4 last year. I tell you those OEM starter relays are not reliable. I changed the one in my ST4 with an automotive one and it works great. Will try and do the same on my 916 if it will fit.
To verify the contact resistance of the solenoid, you can take a voltmeter and place it from the + battery post to the starter lug. Then when you're cranking (forcing a lot of current thru the wires), this will show you any Voltage Drop (VD) along that wire, and anything in between. You can move the probes to isolate the actual connection or item that is causing the problem.
Anything over 0.2 Volts (for either the + wire or the - wire) is a problem. Another way to locate is any connections that are warm or hot to the touch after cranking for about 10 seconds.
I would check the battery to see if it is on the way out. A lot of times if the battery is weak it won't have enough power and you will get a clicking sound at the solenoid. The other post from Stick is good to see if you can isolate the problem, and from Mike about the starter solenoid (relay) is also another good direction. I just upgraded my solenoid from OEM to an automotive type and increased battery and starter cables to 4 gauge. (See post "ST2 starting issue"). The difference when starting the bike is very apparent, as it turns over quicker and with more power.