Author Topic: New (to me!) '77 CB400F - US model  (Read 7035 times)

Offline taysidedragon

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Re: New (to me!) '77 CB400F - US model
« Reply #270 on: July 28, 2019, 12:09:54 PM »
That looks similar quality welding to what's on my UK gear lever.
There's chrome over the weld so probably original.
2010 Street TripleR
1977 CB400F

Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #271 on: July 29, 2019, 02:37:33 AM »
Well there you go.  I just assumed that the OEM would have been a one-piece casting like that after-market job, and therefore my welded one must have been broken and repaired.

I bent it "back" to where it looks like it should be right, but without the bike present, it's hard to know!  We'll find out soon - easy enough to fine tune it later...

Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #272 on: August 31, 2019, 11:00:58 PM »
I went to a local museum's classic motorcycle meet today; saw three CB400F's there, but all earlier than '77.  That late model US version really is the ugly bastard child, isn't it?  Fugly tank, upright bars and forward pegs...  anyway, I wonder if the owner of this one knows what a gold mine he has with those OEM headers in such great shape?

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Offline 10tenmen

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Re: New (to me!) '77 CB400F - US model
« Reply #273 on: September 01, 2019, 08:59:43 AM »
How do you know they are genuine bars ie what’s the giveaway sign thanks.

Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #274 on: September 01, 2019, 12:17:39 PM »
How do you know they are genuine bars ie what’s the giveaway sign thanks.

Well, now that you mention it... I don't know they're original.  Although he acknowledged that the silencer wasn't OEM, he said the headers were, so I'm taking him at his word.

They do look rather shinier than the rest of the bike don't they?

Offline 10tenmen

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Re: New (to me!) '77 CB400F - US model
« Reply #275 on: September 01, 2019, 12:51:32 PM »
Agreed like you say if original they are valuable lol.

Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #276 on: September 01, 2019, 09:53:14 PM »
While digging into my fuse block to help with a wiring question, I found this (click to zoom):

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To be honest, I didn't dig further and I'm not sure which "side" of the fuses this little bodge is on, but I know enough about how electricity moves through conductors to know that this isn't cricket!  The only reason I can come up with for this is perhaps the clips holding the fuse ends weren't gripping securely, so the wire pulls them tight.  Pardon my Français, but really, WTF?!?

It looks like the same kind of job done to hold the ignition switch connector to the broken switch: http://www.sohc.co.uk/index.php/topic,17461.msg153957.html#msg153957

Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #277 on: September 14, 2019, 03:48:55 PM »
No response to my latest post, so just to be sure: that fuse box bodge is an electrical problem... isn't it?

Offline K2-K6

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Re: New (to me!) '77 CB400F - US model
« Reply #278 on: September 14, 2019, 04:36:09 PM »
Take it you mean just the twisted wire there?

Looks like it's been initiated to cope with intermittent connection as you suspect.  Wouldn't in itself do anything wrong if on supply side but would increase fuse rating if on outbound terminals.

(I use a jumper in that location to get a car fuel pump going by taking a supply from cigarette lighter circuit in the event of problem failures)

Looks like the fuse board has problems causing no start or complete stopage on occasion.  In cricket terms "light stops play"  ;D

Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #279 on: September 14, 2019, 05:12:23 PM »
Take it you mean just the twisted wire there?

Looks like it's been initiated to cope with intermittent connection as you suspect.  Wouldn't in itself do anything wrong if on supply side but would increase fuse rating if on outbound terminals.

Thanks K2-K6... your "ifs" got me thinking about that, too, so I removed the fuse block to actually examine which wires on which side of the fuses were shorted.  As it turns out, that twisted wire is connecting the black/red and the brown/blue wires.  Looking at the UK wiring diagram, I believe this would create a short circuit between the "park" and "headlight" positions of the lighting switch on the right handlebar control, so any position other than "off" would illuminate them all.

But this is a US spec bike, with no light switch, which is wired to have the headlight always on when the ignition switch is on - except when the electric start button is being pressed - at that point the headlight is supposed to go off until the starter button is released.  With a short across those two wires, the headlight will always stay on, even when the electric starter is being used, bypassing the protections built into the circuit... such as they are.

I think I'll fix it...  ;)

Offline K2-K6

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Re: New (to me!) '77 CB400F - US model
« Reply #280 on: September 14, 2019, 05:47:38 PM »
I feel it's definitely worth while to get it properly sorted and debugged,  just makes using it easier too.

I'd do the same.

Offline Lobo

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Re: New (to me!) '77 CB400F - US model
« Reply #281 on: September 16, 2019, 01:23:29 AM »
... whilst I don’t have the US wiring diagram mattsz, I’m not sure how connecting the Park & HL will bypass the starter button ‘protection’ - ie I’d have thought the ‘protection’ will continue to work as designed?
My guess at this bodge is that there’s been a break in the Black/Red feed (to the fuse holder) ... and so the PO has jumped the two together.

Has the PO therefore solved the problem and (lazily) restored the lighting to normal road light functioning?  (at the expense of proper Park light function)

Simon.
« Last Edit: September 16, 2019, 03:02:22 AM by Lobo »

Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #282 on: September 16, 2019, 12:13:19 PM »
... whilst I don’t have the US wiring diagram mattsz, I’m not sure how connecting the Park & HL will bypass the starter button ‘protection’ - ie I’d have thought the ‘protection’ will continue to work as designed?

Perhaps "protection" wasn't the best choice of words - substitute "function?"  USA model headlights are always on when the ignition key is on - except when you push the starter button - power to the headlight is then temporarily disconnected until the starter button is released.  So the circuit's "function" is to remove the electrical load of the headlight while the starter is used.  Whether that's a "protection" could be debated, I suppose.  Whatever you call it, with that jumper shorting the two wires in question, the headlight would stay on when the starter button is pressed, which is not the intended design.  I think...  ;)

BTW, if you're at all interested, I've added my version of the USA-spec wiring diagram to the same post that has the UK-spec diagram... link to that thread: http://www.sohc.co.uk/index.php/topic,17969.msg155929.html#msg155929

Quote
My guess at this bodge is that there’s been a break in the Black/Red feed (to the fuse holder) ... and so the PO has jumped the two together.

Has the PO therefore solved the problem and (lazily) restored the lighting to normal road light functioning?  (at the expense of proper Park light function)

Thinking about it, I'm liking this idea - you may or may not recall that my starter switch was broken, and it wouldn't operate the starter properly (pic of the switch in this post: http://www.sohc.co.uk/index.php/topic,17599.msg153989.html#msg153989).  Full headlight current runs through that switch - the "break in the Black/Red feed (to the fuse holder)" you mentioned could very well have been that broken switch - and I wouldn't have realized it because the headlight was getting power through that bodge...

Offline mattsz

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Re: New (to me!) '77 CB400F - US model
« Reply #283 on: October 09, 2019, 01:13:20 PM »
Sorry for my shameless cross post - I posted a question of sorts in the tricks and tips section, which has had 80+ views to date but no replies.  Anyone care to take a look and comment?

http://www.sohc.co.uk/index.php/topic,20253.msg179895.html#msg179895

Offline Nurse Julie

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Re: New (to me!) '77 CB400F - US model
« Reply #284 on: October 09, 2019, 03:17:39 PM »
Sorry for my shameless cross post - I posted a question of sorts in the tricks and tips section, which has had 80+ views to date but no replies.  Anyone care to take a look and comment?

http://www.sohc.co.uk/index.php/topic,20253.msg179895.html#msg179895
A soda blaster has many uses, including the parts you are talking about. No media is left, so no issues with little bits if glass or sand being left but, it is a slow process blasting anything with soda. The outcome and time spent is entirely dependant in the output of the compressor you are using. It needs to be a high CFM rating to do an effective job.
« Last Edit: October 09, 2019, 03:19:55 PM by Nurse Julie »
Im a Nurse, trust me, this won't hurt.....much !!!

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new