Topic: 1975 CB400F Electrics - any wizards out there?

[seabird]

With the exception of a new right-hand switchgear, my 400F is now complete and ready to rock - with a small problem...the electrics are totally dead whether the ignition is switched on or off.

Have checked the fuses, which are all good with current flowing across them, but no lighting, direction indicators or idiot lights - nada, zip, nowt.

The battery is new - dry charged and filled with electrolytes yesterday - now holding a full charge, but this is going nowhere. 

I don't want to add fuel since the carbs have been cleaned, new jets etc and I don't want to run fuel through the system just in case it has to stand due to the non-functioning electrickery and gums up my nice clean carbs.

Anyone suggest where I go from here?

Thanks  guys!

Seabird

[supersport_CB400F]

Get a multimeter and a circut diagram and start checking the iginition system wiring connections

[Sparks]

Check your ground connections.

[oldfart]

Yes, start at the battery and work your way forward.  Next stop the main fuse.  Then the keyswitch.  Then the sub fuses.  Etc.  By the way, put Stabil in your tank and you will not only not have to worry about your gas, you'll be doing something you should do anyway if you even think you may not ride the machine a lot.  :-)

[seabird]

Yes, start at the battery and work your way forward.  Next stop the main fuse.  Then the keyswitch.  Then the sub fuses.  Etc.  By the way, put Stabil in your tank and you will not only not have to worry about your gas, you'll be doing something you should do anyway if you even think you may not ride the machine a lot.  :-)

Thanks for the pointers!  btw  I'm in the UK - wh can I obtain "Stabil" - or is this for the USA market only?

Seabird

[oldfart]

Although made in the U.S. I would be very surprised if Stabil was not available internationally.  It is very common in agriculture/industrial engine use.  Honda sells it under their own name in U.S. dealers, otherwise it should be available at most lawnmower/home improvement/hardware stores.  The stuff really works.  It works by combining with the aromatic compounds in the fuel to slow their evaporation and hence the formation of gum.  Use as directed, including running the engine to get it into the carb jets.  It has no effect on engine perfomance.  However, prolonged (the stuff works for up to two years) storage using Stabil with cheap aftermarket fuel hose may result in deterioration of the hose. 

[seabird]

Thanks a lot Mike- I think I know the very place to start the search!

Seabird

Terry Tyler

[Tim2005]

First thoughts... check the multiplug connector to the fusebox, make sure none of the wires have broken off in particular. Next check the connector on the key-switch, and make sure current is getting there too. Just follow the current from there until you find where it stops. Also make sure the system is earthing- should be no resistance between any green wire and the battery -ve terminal. You can also try the interactive wiring diagram at this site http://oldmanhonda.com/MC/wiring.html  , tho the 400F one there only shows 1 fuse so I presume it's US wiring.

 

[n9viw]

Ditto Tim2005- check your connections. I had a particular problem with the ignition switch plug pulling out and killing the electrics (and while riding! What a rush! ) The previous owner had put it on one of those ignition switch relocator plates that mounted it to the handlebars rather than the frame, and the wires just weren't long enough to reach AND deal with the bars turning back and forth.
Best of luck.

[Zane]

Have checked the fuses, which are all good with current flowing across them, but no lighting, direction indicators or idiot lights - nada, zip, nowt.

My first thought -
Do you mean the battery voltage is flowing across them, or that the tiny test current of a continuity meter is flowing across them?

The reason I ask is because way back when I was a beginner (six months ago) I had a similar problem as you describe.  My fuses were fine with a continuity test, but the soldered connection to the main fuse behind the fuse panel had broken/melted off.  I redid that connection with a set screw and the bike came alive again.

"With the exception of a new right-hand switchgear"

My second thought-
On my '76 400/4 there is a master on/off switch on the right handlebar control.  If that were not wired in, or if it was wired in, but in the off position, my motorcycle would be completely dead electrically.  I don't mean to say "have you checked the on/off switch" but I bring it up because you do say something about not having the right hand switch complete or something ......  I'm just not clear with my understanding of what's going on with your right hand switch.... is it just old, but there, or what?

[seabird]

The right-hand switch gear has the starter button missing - probing into the hole sees a needle swing from no continuity to full continuity
(as I understand it - probably wrongly.
I get no lights of any kind on operating the appropriate switch.

The Left hand switchgear has cabling leaving the swirch (this _should carry the Clutch cut-out cable) - I noticed a gleam of copper wire from this cable just where it leaves the switch - probing into this shows a needle swing to full as above.

I haven't yet managed to get into the ignition switch - but at the moment it doesn't matter which of the three positions I turn the key to, nothing happens to lights, turn signals or the starter solenoid.

Keep going Guys - you'll get me there!   

Seabird

[oldbiker]

Hi Seabird, where are you in the UK? I'm in Coventry and if not too far I could maybe help you sort it out.

[seabird]

Hey there Oldbiker - I'm in Wing, near Leighton Buzzard, (i'm in Bucks, although the postcode is a Bedfordshire one).

It's slowly dawning on me that what I've been doing up to now is only testing circuit integrity with the circuit tester mode on my multimeter, NOT whether the power is getting from Battery to Switchgear/Ignition circuit etc..

So far the connections I've checked in the Headlamp shell and the connections from the h/bar switches are correct, but there are a couple of faultds with the switches themselves (see previous posts in this thread)

Looks like I've got to go power hunting.

Thanks for the offer Oldbiker, but I wouldn't want anyone to come that far in today's balmy weather - my garage is B**dy cold!

[jdpas29]

just a thought, but have you tried to crank your bike with the kickstart?   i think that might narrow down where your problem lies.  if it would start and run then your ignition key switch is ok as well as the on/off right handlebar switch.  then it would be maybe something with the starter and/or other electrical components.  i dunno... just a thought.

i had to completely rewire my bike so i feel your pain.   

[supersport_CB400F]

Have you had the frame powder coated or painted?

[seabird]

Have you had the frame powder coated or painted?

Painted - just a light blow-over since the paint was basically OK.  why?  do you think some of the paint may have got into the connectors?

Seabird

[supersport_CB400F]

I had to remove the powder coating at all the earth points to get  good conduction

[seabird]

It works!!  Halleluja!    Finding the answer took a long hard time, with much great input from this forum, but last night I cracked the problem.

I checked the Battery condition - discharged - Duh!!  so I put it on charge over night and ten minutes ago, I turned the ignition switch and it lit up like a Christmas tree!

Now all I need is for it to stop snowing, the temperature to rise above freezing, and Fuel!

Seabird