Topic: CB400F no start no electric to ignition switch

[914eener]

I’ve got an odd problem that I need some help with.  77 CB400F with 1,600 original miles.  Twice this bike has left me stuck in the last 2 weeks with a no start electrical condition.  It will run fine (rode 40 miles today) and when I turn it off and try to restart it I get no lights on the dash and no electric to start the bike.  When it happened today I checked all the fuses (they were ok).  It has a brand new battery.  I rebuilt the carbs and had a local vintage shop install a Dyna ignition, Dyna coils and Dyna plug wires.  Had to flatbed it home.

Seems like the ignition switch is bad but I pulled it apart today and it is like new in the electrical end.  Cleaned and lubed everything up anyway.  I jumpered the switch plug to bypass the switch and got no electric doing that.  Anyone had this happen to them and how did you get it working correctly?

[Kevin]

You might want to take a lookat the backside of your fuse block. They tend to ywat up and melt and then give you a cold soldier joint.
 
I like to upgrade to a blade style modern fuse block.

Your '77 sounds sweet. I have one with 701 original miles, Candy Anteres Red.

Sent from my SM-N960F using Tapatalk

[914eener]

I pulled the fuse block and it is “as new” with no corrosion on the backside or the plug male/female.  I used some Deoxit on the connectors and the back of the fuse block just for good measure.  Checked voltage on the battery (13.4) and the back/front of the main fuse and it was 13.4 volts also.  Checked voltage at the connector for the ignition switch and it was getting no voltage.  I think I have a wire issue somewhere as there is no power getting from the fuse block to the ignition switch connector.

Anyone have any guidance on finding where the power problem might be without opening up the wiring harness?

Really odd that it would start and run fine and when I turned it off there’s no power to the the ignition switch for a restart.

[dugsgms]

Not sure if it will help but my 400 would exhibit the same issue from time to time(and would sometimes just shut off while riding). Ended up being the fuse, it looked fine but the solder point where the fuse element was attached to the "cup" at the end of the fuse was cracked and would cause a open circuit, a new fuse fixed the problem. Good luck!

[914eener]

Pulled the main fuse again and this time I noticed that I could push both metal ends toward the middle of the fuse.  Cheap Chinese junk fuse is probably not making continous contact on both ends.  Went to my local NAPA and got a pack of made in the good old USA 15 amp fuses.  Popped one in and viola...I have my instrument panel lights back and they are brighter than ever.  Bike fired right up.  Problem solved unless I have this same issue happen again.

Tomorrow I’m going for a ride and shut the bike off a bunch of times to make sure it was a bad fuse and doesn’t do it again.

[Deltarider]

Are you trying to make us believe you did not pinch the clamps prior to fitting them 'good old USA 15 amp fuses'? 

[914eener]

Clamp did not need to be pinched.  It was plenty tight...actually difficult to get the fuse out it was so tight.

[bryanj]

I will put money on those fuses not being made in USA

[914eener]

You would lose...Buss...it was printed on the box “Made in USA”.

We do still make a few things here.

[Deltarider]

Don't make us laugh! Maybe it's better you don't learn what Europe's (or Japan's for that matter) opinion is on the quality of American consumer goods.

[bryanj]

I used to fit Yamaha parts in genuine looking boxes made in Taiwan

[Deltarider]

Tomato paste, made in Italy, is partly arriving in bulk carriers in Italian ports. Recently they've sourced the origin of that tomato pulp. Turned out to be China, where the tomatoes had been picked by enslaved Uyghurs. Put it in a can in Italy and you can brand it 'made in Italy'.

[Alaxy Galaxy]

I ended putting conductive paste on the blades of my fuse block. Otherwise it wouldn't contact ideally and the fuses would heat up so much the ends would unsolder themselves.