Author Topic: Need some help trying to start bike with suspected frigged kill switch (Read 21502 times)

b1jackson · « **on:** June 29, 2016, 05:26:11 AM »

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 · « **Reply #1 on:** June 29, 2016, 06:22:04 AM »

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 · « **Reply #2 on:** June 29, 2016, 06:44:51 AM »

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 · « **Reply #3 on:** June 29, 2016, 07:05:31 AM »

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 · « **Reply #4 on:** June 29, 2016, 07:11:58 AM »

Quote from: strynboen on June 29, 2016, 06:44:51 AM

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 · « **Reply #5 on:** June 29, 2016, 07:13:12 AM »

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 · « **Reply #6 on:** June 29, 2016, 04:09:07 PM »

Quote from: Don R on June 29, 2016, 07:11:58 AM

Quote from: strynboen on June 29, 2016, 06:44:51 AM
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 · « **Reply #7 on:** June 29, 2016, 06:39:33 PM »

Quote from: b1jackson on June 29, 2016, 05:26:11 AM

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 · « **Reply #8 on:** June 30, 2016, 02:07:40 AM »

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?

b1jackson · « **Reply #9 on:** June 30, 2016, 06:15:10 AM »

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

b1jackson · « **Reply #10 on:** June 30, 2016, 07:33:21 AM »

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

b1jackson · « **Reply #11 on:** June 30, 2016, 08:24:10 AM »

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 · « **Reply #12 on:** June 30, 2016, 04:59:16 PM »

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 · « **Reply #13 on:** June 30, 2016, 06:06:08 PM »

Quote from: b1jackson on June 30, 2016, 02:07:40 AM

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.

scottly · « **Reply #14 on:** June 30, 2016, 08:56:12 PM »

Quote from: b1jackson on June 29, 2016, 04:09:07 PM

[ 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 · « **Reply #15 on:** July 01, 2016, 04:45:05 AM »

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 · « **Reply #16 on:** July 01, 2016, 04:51:15 AM »

Where is that 30 amp fuse hiding?

b1jackson · « **Reply #17 on:** July 01, 2016, 07:00:12 AM »

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 · « **Reply #18 on:** July 01, 2016, 07:54:42 AM »

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.

b1jackson · « **Reply #19 on:** July 01, 2016, 09:33:35 AM »

Yes. That will be on the list eventually. I had the box off and apart. No loose connections or solder, cleaned and polished with vinegar/salt then baking soda water mix.

Still baffling why I'd have 12v at the solenoid but no ignition

b1jackson · « **Reply #20 on:** July 01, 2016, 11:11:49 AM »

Ok, I appreciate the fact that solving a no ignition issue via forum posting is a tricky one so I am trying to be very systematic here with my steps. Forgive if I write in an obvious step as this is a learn as I go process on a bike I've never heard run and have had for a couple of weeks only.

Testing process of key switch

- removed and unplugged the switch. Wires feeding the switch in the harness are red, black, 2 brown wires and a brown/white wire. The only wire receiving power was the red (12.3 volts)

- I plugged the key switch back in after cleaning the connections and adding some dialectic grease to the connections. All snug and clean. Turned key to the on position and the power was going to the black and red wires only (12.3 volts @ each).

- I then turned the key to the park position. Tail light lit as it always has but no other lights. I checked and had power to the two brown wires, the red wire, but not the brown/white one or the black. (12.3 volts @ each).

Where should I go from here?

b1jackson · « **Reply #21 on:** July 01, 2016, 12:23:06 PM »

Yeh, I'm going nowhere alright

Good to know that I've eliminated the key switch as the culprit to no ignition. I had looked at the wiring diagram but not such a clear one. Looking at it and truly understanding it are two different things.

If I've got power as I've described in my recent post and power at the fuses, solenoid, etc would it be possible I have a bad ground?

b1jackson · « **Reply #22 on:** July 01, 2016, 06:30:51 PM »

Here is an update to my misery and testing process in case anyone can help me narrow this down.

After my earlier confirmation that my switch was working correctly (thank you calj737), I wanted to test for power at the stater button. Turned the key to on position, and no power to any of the right hand switch. Cleaned it out with contact spray for electrical and will reassemble tomorrow. A couple of the wires feeding into the switch looked a bit pinched so I'll put some liquid electrical tape on the before I button things back up.

I'm at a loss and I think I've covered a lot of the obvious ground! Help guys....I want to hear this beast running!

scottly · « **Reply #23 on:** July 01, 2016, 07:08:40 PM »

The black wire from the ignition switch connects 12V to the horn, the brake light, the nuetral and oil pressure lights, the voltage regulator, and via the kill switch, the coils. (The input to the kill is a solid black wire, and the output to the coils is a black wire with a white stripe) With the key on, test for 12V at the black regulator wire.

b1jackson · « **Reply #24 on:** July 02, 2016, 03:29:46 AM »

Thanks for staying with me on this. I'll check this later today and check back.

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Author Topic: Need some help trying to start bike with suspected frigged kill switch (Read 21502 times)