Author Topic: Starter button no go.  (Read 458 times)

Offline Athame57

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Starter button no go.
« on: January 03, 2026, 12:17:23 AM »
Electrics, my favorite topic  ::) Pressing my starter button is doing nothing, sometimes when this has happened I've hit the button with the kill switch on, turned it back and hey presto...voom voom. Alas, this past week nothing happens whatever I do. Kick start works fine and battery plus all other electrics just fine. I'm not sure if I should tinker with the switch gear or find out (how?) if the starter solenoid is up the creek.  :o  Any suggestions?  8)
I brake for animals!
1978 CB400F2 called Elen.

Offline taysidedragon

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Re: Starter button no go.
« Reply #1 on: January 03, 2026, 01:04:42 AM »
If it's starting with the kickstart the problem is most likely bad contact at the starter button or a problem with the solenoid.
First and easiest attempt to fix would be spray some contact cleaner or wd40 down the edge of the starter button and see if that makes any difference.  Living outside there may be moisture or corrosion inside.
If that doesn't work you'll have to dig deeper, taking the switch halves apart. You can bridge the solenoid or bypass it temporarily but if you don't have the tools or cables it would be best to get help.
Gareth

1977 CB400F
1965 T100SS

Offline Bryanj

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Re: Starter button no go.
« Reply #2 on: January 03, 2026, 03:43:38 AM »
Right, depends on how old the bike is, early bikes grounded the yellow red wire to the handlebars, later ones with starter safety circuit put power to the solenoid.

You need to undo the RH switch and see how many wires and what colour go to the starter button

Offline TrickyMicky

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Re: Starter button no go.
« Reply #3 on: January 03, 2026, 08:24:20 AM »
I am NOT an electrician, but before you start pulling things apart, a couple of simple checks. IS the neutral light working? If you have the clutch switch fitted, try it with the lever pulled in.  With the ignition on, get an old screwdriver and bridge the two large terminals on the starter solenoid to check the starter motor, providing that the battery is fully charged!! Take the headlamp out of its shell and look for any bullet connectors that may ahave parted. If none of this works then you will have the PITA job of splitting the handlebar switch. Best of luck, Mike.

Offline K2-K6

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Re: Starter button no go.
« Reply #4 on: January 03, 2026, 09:03:28 AM »
If you go to the "signal" wire that commands the starter solenoid, then provide input to that to see if it starts.

This effectively splits the system in half to see if the problem lays in the request part or the action part switching and running motor to turn the engine.

Check the terminals are tight on, successively the battery, the solenoid large terminals, the starter motor, as they won't take the load needed if loose, but may give you that intermittent situation.

Offline exvalvesetdabbler

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Re: Starter button no go.
« Reply #5 on: January 03, 2026, 11:54:44 AM »
It's also possible that the brushes in the starter motor are stuck in their slots, they wear down over  time resulting in less spring pressure and add in a bit of carbon dust gumming up the slides.

A jump lead from the battery +ve to the starter motor terminal( need the sprocket cover off to access) should make the motor spin.  Alternatively a thick screwdriver across the starter solenoid terminals  should make it spin up.

However if this was the case you would still hear a click from the solenoid when you press the start button but no starter motor.

So
If the solenoid clicks when you press the button  - check as above
If the starter solenoid doesn't click - check wiring and switches, that includes all the bullet connectors in circuit, IE pull apart connectors , squirt of WD40 then re connect and disconnect a couple of times to wipe the contact.

My first port of call though would be to drown the handlebar switches in WD40 while exercising them, do it a few times, mopping up with a tissue in between. This means splitting the two halves of the switche gear to get at them. The starter button contacts can get quite gunked up with all the lube from the throttle cable attracting muck.

Regards
Dave


« Last Edit: January 03, 2026, 03:44:21 PM by exvalvesetdabbler »

Offline Rayzerman

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Re: Starter button no go.
« Reply #6 on: January 03, 2026, 01:37:02 PM »
FYI, there are plenty of starter button kits available, should that prove out to be the issue.
'72 CB350F, 2010 CBF1000FA

Offline Athame57

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Re: Starter button no go.
« Reply #7 on: January 04, 2026, 01:51:24 PM »
I am NOT an electrician, but before you start pulling things apart, a couple of simple checks. IS the neutral light working? If you have the clutch switch fitted, try it with the lever pulled in.
Pulling the lever worked!  ;D I've opened up the switch housing and sprayed in WD40. I'm not there yet, too cold to work outside at my age, but things look like there're going to be sorted.  8)
I brake for animals!
1978 CB400F2 called Elen.

Offline Seabeowner

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Re: Starter button no go.
« Reply #8 on: January 04, 2026, 07:00:51 PM »
If this is now only starting when the clutch is pulled in I think there is a fault in the starter safety circuit. It is supposed to start if either the clutch is pulled in OR if it is in neutral. If the neutral light is working this means the neutral switch connection is probably good. There is a diode under the L side panel that could be U/s or a poor connection. Check LG/R wire....when it warms up a bit....maybe April.
Phil
1971  CB500K0  Candy Jade Green or Candy Gold
1973  CB500K1  Candy Ruby Red
1975  CB550F1   Shiny Orange

Offline Athame57

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Re: Starter button no go.
« Reply #9 on: January 04, 2026, 10:39:28 PM »
If this is now only starting when the clutch is pulled in I think there is a fault in the starter safety circuit. It is supposed to start if either the clutch is pulled in OR if it is in neutral. If the neutral light is working this means the neutral switch connection is probably good. There is a diode under the L side panel that could be U/s or a poor connection. Check LG/R wire....when it warms up a bit....maybe April.
Hi
Do you mean this? https://www.davidsilverspares.co.uk/by-part-number/hpart_31700124003
I brake for animals!
1978 CB400F2 called Elen.

Offline Ken4004

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Re: Starter button no go.
« Reply #10 on: January 05, 2026, 06:17:26 PM »
I had a similar issue when rewiring my bike, starter button not working.

I checked the wiring with a volt meter and had no continuity at the switch so decided to take it apart and found lots of corrosion the green copper type.
Stripped the switch down and cleaned up all the contacts and the switch started to work, it’s just a basic push button switch to make the circuit but the design is not great and a bit fiddly to put back together but like everything else on this bike just needs a bit of patience.

I had exactly the same issue with my Z1000 a couple of years ago , water gets into the switch and corrosion takes over.After I cleaned everything up added some switch cleaner to ensure good contact at the switch.

Offline Bryanj

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Re: Starter button no go.
« Reply #11 on: January 05, 2026, 06:20:22 PM »
That ds part is the later version, early version was a big box with a multi pin red connector

Offline Athame57

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Re: Starter button no go.
« Reply #12 on: January 05, 2026, 07:52:16 PM »
That ds part is the later version, early version was a big box with a multi pin red connector
My bike is a 1977 build, 1978 registration. F2  8)
I brake for animals!
1978 CB400F2 called Elen.

Offline Bryanj

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Re: Starter button no go.
« Reply #13 on: January 05, 2026, 08:34:31 PM »
Never really looked closely at the system but i thought the diode worked on both clutch switch and neutral light

Offline exvalvesetdabbler

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Re: Starter button no go.
« Reply #14 on: January 06, 2026, 05:22:17 PM »
It's easy enough to test the diode if you [ Guests cannot view attachments ] have a multimeter of failing that , a battery, small bulb and some wire. A pilot light bulb or similar would do.

Just connect up the bulb to the battery and confirm that the bulb is good. Connect the diode in series with the bulb and test again.  Connect the diode opposite way round test again.

Bulb lights up both ways - diode shorted
Bulb doesn't light either way - diode open circuit
Bulb lights up one way and not the other - correct

I would be surprised if it has failed, they're pretty reliable devices unless they suffer abuse through  over voltage or excess current.

If it the same as mine , the diode symbol is marked in the molding of the plastic.

Regards
Dave