Topic: Need some help trying to start bike with suspected frigged kill switch

[b1jackson]

First let me tell you abit about my project.  Purchased a CB750 that hadn't been on the road the past couple of years.  Based on some info from the PO, I swapped in a new starter relay in hopes to hearing the bike run.

New battery is in and I am just trying to hear it run before sinking too many parts into it.  I would like to use the starter vs. trying to kick over a bike that hasn't ran in a few years.  My leg won't take that abuse!  Things I've also done:

- cleaned connections (with vinegar) in the fuse box.  Cleaned all connections to the starter relay, etc.

When I look at the RH kill switch, the starter button is missing (broken) and the PO thought the switch was buggered.  When it broke, he just used the kick starter.

How do I safely run a jumper to have the bike crank and start (hopefully!).  The "+" on the battery to which coil on the wire?  I should add that its had an electronic ignition put in if that matters any. 

When I turn the key, I get no dash lights, headlight, etc. but I do get a rear tail light which is an aftermarket LED one wired in.  Because of the fact that it lights, I don't think its the key switch I have to go after...its the starter switch.  Also, is there a HOW TO for removal and re-install of this switch? 

[rocks]

If you just wanna make sure the bike turns, first make sure it has oil. I would personally kick it over to lubricate the cylinders and other things.

Taking the RH switch isn't hard. I don't know what year is yours, but mostly, the starter switch has three wires.

Black- powers the the starter switch
Yellow/Red- Comes from starter relay(Solenoid)
Black/Red - Goes to the headlight (fused).

You can jump the Red/Yellow and the Black at the push button with a 16 awg wire or something.
You may wanna consider cleaning the carbs as well.

 

[strynboen]

just put positiv 12 volt on the coils hvere the Black vires used to go inn then you have ignision on......then short the solonid...so the starter turns..then you start the bike..no need to use key

[b1jackson]

Sorry, forgot to add its a 1975.  I did an oil change on it and have kicked it over a few times to bring oil into the cylinders.  I do have a key.

[Don R]

just put positiv 12 volt on the coils hvere the Black vires used to go inn then you have ignision on......then short the solonid...so the starter turns..then you start the bike..no need to use key

 This bypasses the key switch. and everything else. It eliminates other wiring issues for the sake of getting it started.

[b1jackson]

Ah, I see.  So just shorting the solenoid doesn't fire the coils.  I need to hook up + from battery to them first and then leave this wire on while the bike is running correct?

Seems simple enough.

[b1jackson]

just put positiv 12 volt on the coils hvere the Black vires used to go inn then you have ignision on......then short the solonid...so the starter turns..then you start the bike..no need to use key

 This bypasses the key switch. and everything else. It eliminates other wiring issues for the sake of getting it started.

Ok. I've run into some issues as maybe I interpreted this wrong.  I have 3 wires going into my coils (and these are an electronic conversion if that matters). Yellow, blue and black/white.  I disconnected the black/white ones and plugged theses wires coming from the coil directly to my + battery post with a jumper wire.  Wire got hot, sparked and didn't cooperate so I unhooked. 

Am I supposed to be unhooking or just tapping in? 

[scottly]

I would like to use the starter vs. trying to kick over a bike that hasn't ran in a few years.  My leg won't take that abuse!
When I look at the RH kill switch, the starter button is missing (broken) and the PO thought the switch was buggered.  When it broke, he just used the kick starter.

How do I safely run a jumper to have the bike crank and start (hopefully!).

Regarding the electric starter, disconnect the two small solenoid wires from the harness, connect one to ground, and when the other is momentarily connected to battery plus the starter should spin the motor. Caution, this should be done with the bike in neutral and ON THE CENTER STAND! Ask me how I know...    

[b1jackson]

Yes.  Ok.   And this should start the bike? I know the starter spins when I arc the solenoid posts but will the method you suggest give me spark to fire the engine?

Does it matter which of the small solenoid wires I hook to the battery?

[calj737]

And this should start the bike?Should, but depends upon other factors allowing the bike to "start".
...but will the method you suggest give me spark to fire the engine? Yes.

[b1jackson]

Thank you.  And it doesn't matter which small wire from the solenoid is grounded or goes to the '+' battery post?

[calj737]

Best to use the stock scheme then you won't get crossed up

[b1jackson]

Not a stock relay so I assume red wire on solenoid to red on battery

[calj737]

Run the thin red wire to battery +, the thin blue to ground. When you make that connection, the solenoid will trip the starter if you have already secured the screw stud to battery + and the other to the starter motor. So do the solenoid last, and make dead certain your bike is in neutral!

[b1jackson]

yes, thank you very much for your help.  Bike is on the center stand and in neutral.  Looking forward to firing this baby up tonight!

[b1jackson]

Arghh!  No spark.  I hope I didn't cook my coils when I tried the earlier methods of battery to coil.

Hmmmm...but I also disconnected my rear brake switch because it was busted.  Could this be the culprit?

[scottly]

Yes.  Ok.   And this should start the bike? I know the starter spins when I arc the solenoid posts but will the method you suggest give me spark to fire the engine?

No, this is only to spin the starter, but with less sparks than shorting the posts with a screwdriver.
The kill switch is a different circuit than the start button. You mentioned you only had a taillight with the key switch on. The key has three positions: off, ignition on, and "park". If you are turning the key all the way to the third position, the only thing that operates is the taillight. The switch should be in the middle position for the ignition and other circuits to work. To test the stock wiring with a meter, measure the voltage between battery - (ground)and the coil black/white wires, with the key in the middle position, and the kill switch set to run.

[calj737]

Yes.  Ok.   And this should start the bike? I know the starter spins when I arc the solenoid posts but will the method you suggest give me spark to fire the engine?

No, this is only to spin the starter, but with less sparks than shorting the posts with a screwdriver.
The kill switch is a different circuit than the start button. You mentioned you only had a taillight with the key switch on. The key has three positions: off, ignition on, and "park". If you are turning the key all the way to the third position, the only thing that operates is the taillight. The switch should be in the middle position for the ignition and other circuits to work. To test the stock wiring with a meter, measure the voltage between battery - (ground)and the coil black/white wires, with the key in the middle position, and the kill switch set to run.

We are jumping around here a bit...

Earlier, he had his coils (B/W) directly wired to power from the battery. This solenoid jumper was to be a test of spinning the starter with the coils wired hot to determine if his bike would fire. I'm not sure if out overlapping advice and timelines is confusing him or me more 

But, you need switched power (preferably) to your coils BLK/WHT (as Scottly mentioned with the key switched) and your solenoid wired, plus the jumpers to momentarily excite the starter to get spark and the starter together.

Hope that clears everything up. At least it did for me...

[scottly]

[ I have 3 wires going into my coils (and these are an electronic conversion if that matters). Yellow, blue and black/white.  I disconnected the black/white ones and plugged theses wires coming from the coil directly to my + battery post with a jumper wire.  Wire got hot, sparked and didn't cooperate so I unhooked. 

[b1jackson]

Okay.  I'm going to do some looking into the basics of ignition as I have nothing.  No dash, no indicators, horn etc.  The only light I have is the LED tail when the switch is turned to the park position. 

The PO just told me that everthing was working as normal (including the kill switch) so it has to be something simple.  Fully charged battery that spins the starter no problem.

I saw someone posted a basic wiring diagram so I best study that.

[b1jackson]

Where is that 30 amp fuse hiding?

[calj737]

The stock bike doesn't use a 30A fuse. That diagram while functionally correct, is not application specific. Your MAIN fuse is probably a 15A (depending upon year). You should be evaluating your bike with the key in the first position, not PARK. In PARK, you will only have TAIL and in some cases HEADLIGHT. But not IGNITION.

[b1jackson]

Yes, ok.  I read another post by Scottly desribing how to use the multi meter for the battery to get 12 v and then check each fuse in the fuse box.  I'll do that and check back.

[b1jackson]

With the key in the off position and the multimeter set to volts.

- 12.3 volts at the top of the battery posts
- held the black multi meter lead to the "-" on the battery and moved to the fuse block and got zero reading at all fuses except the main which gave me the same 12.3v reading (which is good) and the bottom one (which is a spare with no power to it) showed a reading of 7.3v.  I thought that was a little whacked so I took out the fuse block and removed the brass clips for the bottom spare altogether.  The lead terminals for the main had melted abit and I wonder if there was some voltage bleed to the next terminal happening.

The PO said that he tried to start it one time with the negative unhooked (maybe he meant off the solenoid?) and it blew (and maybe melted) the box abit for the main fuse.  Any thoughts on what else this whoops could have affected?

All fuses in the block were removed and checked.  Zero ohms in each and every one.

[calj737]

From that description, I would strongly encourage the removal of the fuse block, and a full and proper cleaning of both sides of it (front and back). Inspect it carefully, and if theres evidence of melted plastic or burn marks on the connectors, replace it with a new, ATC type blade fuse box.