Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: Velofello on August 10, 2017, 04:15:19 PM
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I can start my 400/4 up on the button ,but after about 3 to 5 mins it stops with total electrical failure. No lights, no neutral lights no horn. Leave it for about 5 mins hey presto it starts on the button. If I ride off it will fail again whereupon I wait at the side of the road for electricity to return and off I go . Not a very good way to travel !
Battery is in good condition . I have checked the obvious eg earthing, battery connections and wiring damage but nothing immediately obvious.
Any suggestions(polite!) as to where to look/ check next
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Total electrical failure means some sort of disconnection (like a blown fuse).
You say that it comes back on - is this after the bike has cooled down a bit?
My guess would be some sort of high temperature failure with the fuse or fuse holder that "re-connects" when cool.
Ash will know... :)
Steve
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Thanks for the response. Yes the symptoms are as described. The bike starts after it has cooled down. I don't even get any life from the starter button when it fails.
I was thinking high temp failure but of what ? Your suggestion of fuse or holder seems to make sense as I have had problems with a previous 400/4 failing in this area, though not in the same manner as my current one. That was yellow too !
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That was yellow too !
There's your problem then - get it repainted a different colour!
Seriously, it could be a fractured solder joint that just expands with heat.
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I have had a few bikes have that issue over the years, 750F1 & 2, 400 fours, 550F1 & 2, and a Cb650. There was a common problem with them all, the ignition switch. On some, the switch needed taking apart and a loose rivet that held the terminal pins in place peened over with a hammer to make them tight again, on others the plastic switch part had come loose/ become dislodged from the metal lock body causing your symptoms intermittently. Often the plug on the loom to the ignition switch will show signs of heat damage, as poor connections increase resistance, which produces heat.
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I would agree with hairy, check your key switch. The other is the fuse box, if its original (as image) take it off and check the terminals at the
rear. The copper and solder terminals may look OK, but they will become brittle/overheated with age.
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The socket for the fuse holder, a 6 way block with spades, is a favourite for bad contacts. The contacts go green and cruddy which can lead to overheating due to the amount of current flow. The fuse holders themselves may need a polish with autosol so they make a reliable contact.
The key switch could have intermittent contact. Strip, clean and grease to keep the moisture out.
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Thanks for all your replies. They all seem to be pointing me in a similar area, ignition switch & fuse holder. When I get some free time I will look at these and report back as it may help others. Of course the obvious solution is to stay away from yellow ones !
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Had this some years back on my 400/4. Turned out it was dirty connections where the main fuse sits in the fuse holder. Cleaned it up and it has been fine since.
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Try getting an aerosol of proper contact cleaner and go through the fuse box and ignition switch. Bit of scotchbrite will help as well.
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Mine was a fuse wire had parted company with the ends- after nearly 40 years.
i replaced the fusebox from a better 2nd hand one and all the fuses, off course. that fuse would 'make' contact again when it cooled down!! fag packet paper got me home-