Topic: Starter safety switch burnt

[splittie]

Well, I finally found a cb750 that was local and in my price range.
I havent been able to do much with it yet other than put the carbs back on (PO cut off the boots for some reason) and put the engine covers (stator, etc) back on with some replacement screws (again, PO dismantled)
Now I put a battery into the beast and when I push the starter button, the solenoid just makes a buzzing noise and I get nothing when I try to kickstart it with the clutch handle pulled in.
The starter 'safety switch' is totally fried (I mean burnt up) and I haven't seen anywhere that sells them so far.
Any chance this 'safety switch' can be bypassed or replaced??
I would like to at least get this bike running so my wife won't give me such a bad time about 'spending money we didn't have' (Sound familiar to anyone?!?!?)
Any help would be great.

[Bodi]

If the solenoid is buzzing then the starter is trying to work, look for wiring harness issues like corroded or burnt bullet connectors that are losing voltage. A bad start switch is a common problem too, on models years where the starter also shuts off the headlight. The headlight power through the switch (on all the time except while starting) tends to cook the switch contacts.
You can't kickstart with the clutch pulled in, the kick turns the gearbox so the clutch must be engaged to turn the crank.
First I would go through the entire harness and rejuvenate every bullet connector (this si the first thing I do with an old bike showing electrical gremlins) there are lots of threads here about this process.
Remove the solenoid (disconnect the battery negative cable first!!!) then disassemble it. It's pretty obvious how it comes apart. Remove the two threaded posts and file the contact tips flat and shiny. File the contact bar face flat and shiny. Clean the solenoid bit with pure isopropyl alcohol , it should not be lubricated. Put a bit of dielectric grease on the contact faces and reassemble. Connect the red wire - after cleaning off the terminal - from the battery and also the small wires, but not the wire to the starter motor. Conenect the battery again and make sure both ends of the ground cable are secure and making a good connection. Now test the start switch. You should hear a nice solid CLICK! from the solenoid. Connect the starter motor cable. Try again. If it buzzes again, you have either a bad battery (unable to provide the 70 - 100 amps that the starter motor requires) or a bad starter motor (shorted out and drawing way more amps than is correct).
The starter safety switch - what do you mean? There's a small switch on the clutch lever. The neutral switch is also involved. The safety box is really just a diode connecting the neutral switch circuit to the clutch switch circuit - you should be able to electric start the engine only in neutral or, if in gear, with the clutch disengaged. The diode just avoids having the neutral light come on when the clutch is pulled in - that happens if you just connect the two circuits directly. Some other bikes also disable the electric starter if the kickstand is down but no SOHC4 has this as far as I know.

[splittie]

The starter safety switch - what do you mean?

I guess I used the wrong wording.
The fiche calls it a 'safety unit' with the part number being 3856440-001
Thanks for the info you have given
Props to you for such detail

[CBGhia]

You can also find out if it is the starter itself by jumping the solenoid.  Just touch a screwdriver from one post to the other and see if the starter turns or tries to turn.  If you get nothing but sparks then the starter is probably locked up.   Only do it for a second.

Some may not like that method much  *shrugs*