Airman! Go into your profile and edit it to include bike year/model and your location! (hehe - I used to be a buck Sgt in the Army about almost 35 years ago so consider the order a request from a moderator).
OK, FIRST PROBLEM... What the heck is the problem? Your description has led to what I suspect are "rabbit trails"... info leading down blind alleys.
The bike turns over some times and doesn't turn over at other? Is this the issue?
First, test the starter. There are TWO lugs on the starter solenoid. Take a piece of 14 ga. or thicker wire and touch the POSITIVE battery terminal with one end. Touch the other end to the lug on the solenoid where the starter cable is connected. It is a thick and black shielded cable... Looks like a 6 ga. cable. If the starter spins nicely (put on centerstand and in neutral while you do this), the starter is OK.
Next, test the starter solenoid if the starter proved OK... Look at the solenoid. There are two big lugs on the solenoid. One had the starter cable and the other doesn't. Ignore these. There is yet another connection. This connection has a black wire soldered to it. This is the one we want. Take the 14 ga. wire length you used in the previous test. Touch one end on the POSITIVE battery terminal and touch the other end on the place where the black wire is soldered. Does the starter turn over as it should? If no, the starter solenoid is the problem. If it turns over OK... the problem is in the wiring that gets the trigger voltage TO the solenoid. The trigger is that little black wire that is soldered on the solenoid.
OK, to get that trigger power to the solenoid to trigger it, here is what happens... power comes from your stator, it turned to DC and made the right voltage by the reg/rec and then goes to your battery and the main fuse as it comes out the reg/rec. It then goes to your ignition switch where it comes off the ignition switch and goes through the right hand switch gear kill switch. Out of the kill switch, it goes over to the LEFT HAND clutch perch where it goes through that interlock switch. When you pull in the clutch lever, it closes the loop and sends power to the starter button back on the right hand switch gear. When it comes off the kill switch, the wiring for all that mess is BLACK. It is 18 ga wire I think. In any case, the power comes over to the starter button. When you push the button, it then completes the circuit and goes to the solenoid. The voltage tickles the solenoid and causes the contacts to close and voltage flows across the solenoid to the starter.
If the starting is intermittent, start by checking connections. Start by pulling every connector in the path I described AFTER the ignition switch... Do it one connector at a time. Find the connector between the ignition switch and RIGHT HAND SWITCH GEAR that carries the power to the kill switch. It is a large multi-pin connector in the headlight shell. Open it up and clean the connectors with contact cleaner. You can buy this stuff in the computer section in Walmart and most autoparts stores. Once you clean the connectors, dab them with dielectic grease. You can buy a tube of this stuff in the autoparts store as well. This keeps the contacts free of oxidation. Anyway, look for the BLACK wire coming out of your switch gear and going to the left safety interlock switch and find its connector. Disconnect and clean/grease as before and button it back up. Do the same for the connection on the interlock switch and then follow the wire back to the starter button. Open up the switch gear. The starter button itself is often an issue. You can disassmeble it and clean the metal contacts by LIGHTLY brushing them with an emory board or steel wool. Don't get too carried away as the contact metal is thin. I would also not use dielectic grease on the button contacts as it will collect dirt in an open space like in the switch gear. Out of the switch gear, the black wire runs in the bundle to another major connector where it hooks into the main wiring harness. This connector may be in the steering neck or on the outside of the steering neck. Open, clean and grease.
Now retry the starting... If it still starts poorly, either the interlock switch is buggy OR you need a new starter button. The switch can't be serviced. You can bypass the switch to check and eliminate the switch as a problem. Unhook the wire coming off the kill switch before it hooks to the interlock switch. Then unhook the other side of the black wire loop from the interlock. Both ends will have female bayonette type connectors. Put one end of that piece of 14 ga wire into one of the female connectors and the other end into the other female connector. Don't bother pull in the clutch interlock. Just hit the starter button. If the starter spins as it should, your switch needs replaced or you can just fix a permanent jumper to replace that piece of 14 ga wire. If the starting problem persists, the starter button is the problem. Z1enterprises.com can sell you a new starter button. Drop them a note and tell them what you need as the button likely doesn't show on their web site.
I think some part of this troubleshooting should fix your problem. If not, don't hesitate to drop me a note or visit our Vintage Bike Tech Forum via our website homepage.
