I have a 2003 vulcan classic 1500. When I turn on the ignition switch the power comes on but when I hit the starter everything goes dead.After a few seconds with the switch left on the power comes back on and when I hit the switch it goes dead again. I checked the battery connections and check the battery and all is could.Any suggestions

short in ignition switch- common in these bikes.. check it carefully

solenoid jammed on...

TO ALL VN1500 OWNERS....This once happen to me,
I went to the garage to start the bike "Nothing ""The first thing is the lights are bright but no turning over,Next you think the solenoid is kaput but the answer was very simple and the fix takes 30 seconds..
Do not take the bike to bits looking for other problems and look at the clutch leaver and you will see some wires going into a plastic shroud going into the switch in the clutch leaver, Make sure this has not popped out if its connection as it some times may do after a few years due to constant turning on the handlebars,
When this is not connected you will have a bike that will not fire up but comes alive and you will hear a clicking noise but this is from the engine carb area and every function of the bike will work but it will not turn over, Worth looking at and saves sixteen quid for a starter unit you never needed.

Have you checked if the power is reaching the starter ?
And the earth lead from yhe motor to the frame for corrosion or looseness ?
If the power is getting to the starter when you press the button and the leads are all clean then the next thing to check would be for a dead field on the sarter motor. Remove the starter and turn the armature around a bit then see if it works. this can also be the case if the brushes are worn.
Whether you can get the motor to work or not if you are satisfied that power is present at the stater motor when you activate the starter button, then the starter motor needs a service or swap. Do not trust it if you get it to spin after turning it as it will let you down at the worst possible time according to Murphy.

Measure the voltage on the starter side of the solenoid with the kill switch ON and the key ON and the starter switch PRESSED - trans in N. IF it is not 12 volts, it may be faulty.

If you take a voltage reading at the battery when you are pushing the starter button, my guess is you will have 11-12vdc until you push the button and it will drop off. It sounds like your battery doesn't have enough current (cranking amps) to engage the starter. That is why the headlight will work until you try to start the bike and then the light goes out. It is pretty common for motorcycle batteries to go bad every 2-3 years. How old is the battery?

Even though accesories turn on, doesn't mean there is a good enough battery cable connection to turn starter. Also you can test power to solenoid while turning key with a voltmeter. Then you can determine where power goes and stops. It may be solenoid or ignition. It is easier with voltmeter and testing

Perform a leakdown or compression test on the bike before you go to the expense of a top end rebuild. You may find it is something as simple as the rear cylinder not firing properly or perhaps fuel mixture to that cylinder is not correct.

Post a picture of the plugs that are fouling. Are the ignition wires crossed back there? Both plugs may not fire at the same instant, some dual plug setups fire slightly apart (although I can't think of a way that would cause severe fouling like you describe.)