Honda-SOHC
SOHC.co.uk Forums => CB350/400 => Topic started by: smoothoperator on November 09, 2020, 05:18:57 PM
-
I'm researching this topic and finding that there is a lot of information, so I'll keep looking. In the meantime could anyone shed some light on a couple of points? Current situation is that kill switch doesn't kill the engine in either of the off positions. Can I test its function without actually firing the engine up, which is tricky at the moment because of intermittent fuel overflow. I have a multi meter. I haven't found a black/white wire in the headlamp shell as yet. As I understand things this wire routes to the coils, so with the ignition on I'd expect to see a voltage, but where to measure it? Looking at stripping the r/h switch unit but even removing this is looking tricky to me at the moment, with wire tight into the handlebars, throttle cables to disconnect and handlebar to remove there is quite a bit to learn. I'm a bit baffled at the moment, any help would be appreciated.
Just noticed the loom from the handlebars routes to underneath the tank so I can eliminate searching in the headlamp shell.
-
You’re on the right track; you need to place the Red probe onto the B/W wire under the tank, and the Black probe onto the battery negative (or KNOWN good Earth). (Black circle in the pic). The ignition will need to be ON.
The B/W wire has two possible connectors you can use; either the one in the ‘boot’ forward LHS of the tank (Blue circle in the pic).... or by the coils where the feed splits (Red circle in the pic). (you do not need to disconnect the connectors, tho’ a slightly lower voltage reading will result)
An odd failure: my early guess is that the kill switch (or it’s wiring) has failed in the past, and the PO has simply directly connected the coils to the ignition, bypassing the kill switch circuit.
To test the Kill Switch functioning, you’ll need to disconnect both its Black and B/W connectors within the boot. (These are both within the Blue circle).
(To set the meter select the lowest Ohms range, and touch the probes together - you should see close to 0 ohms.)
Now put the probes across the Black MALE and B/W FEMALE connectors of the kill switch, and check its continuity in the OFF / ON / OFF positions. In OFF you should see Infinite ohms (open circuit), and in ON you should see close to 0 ohms.
Wiggle the handlebars / loom whilst doing this check, see if anything changes... bad loom etc.
The Kill switch is indeed a pain to remove / service. As a starter for 10 it might just be worth shooting a good squirt of WD40 into into any nearby switch orifice!
Good luck...
PS - whilst the safety implications are obvious, in this current state of ‘permanent’ Kill function ON you may burn out a coil / flatten the battery when the ignition is ON & engine not running for any length of time.
-
Aside from your mates overtaking you and activating your kill switch it has always baffled me as to its purpose.
I do not recall any of my Mopeds,Scooters or British Bikes having such a device though my memory could be defective. That said if its fitted I want it to work!
-
It's very unlikely that the kill switch could go faulty in this way. I've had one open circuit, but never a short circuit.
It's more likely a previous owner has been meddling with the wiring, perhaps to repair an open circuit switch.
-
Thanks guys, great help for me to test this now. Meanwhile I have found a smoking gun. I have put an image in below along with a couple of pic's of the coils. There is a disconnected black wire from the r/h handlebar and a likely looking home for it, both circled. The female circled is a double connector which has 1 black/white and 1 black - although the plain plain black is difficult to see in all the grime.
There are 2 other empty females in the bag but these are orange/white and light blue/white.
The only dodgy bit I have arrowed as it is very poorly connected and is thinner than the rest of the wires. This might be a red herring/future issue/no issue.
https://photos.app.goo.gl/AvCtaW7HwqH5YLcx6
-
The 2 photos showing coil connections seem OK to me.
The 3rd photo is a little confusing as things difficult to make out.
But.... it appears that the Kill switch 12v supply (Male / Black) connector has been disconnected and is floating free. (there is potential for a short circuit here - it should be insulated / taped up)
Normally, Black would never be directly connected to Black / White, and because you have this, I (still) reckon the PO has bypassed the (faulty?) Kill switch and wired the coils directly to the ignition. (Ie 12v Ignition Black now directly feeds the coil Black/White supply line.)
(The White wire is normally the 12v supply from the Lo Beam switch to the headlamp bulb, and is not part of this problem. I’ve no idea of Orange / White and Blue / White wires; Orange and Blue are normally L & R Indicator supplies: my guess is your loom may have options for American running lights - which would explain why they’re not used?)
As I see it, you need to ascertain whether the Kill switch is serviceable as described in my earlier post. If not you’ve 2 choices... continue as you are (being mindful of burning out the coils) or replacing / repairing the Kill switch.
-
Aside from your mates overtaking you and activating your kill switch it has always baffled me as to its purpose.
I do not recall any of my Mopeds,Scooters or British Bikes having such a device though my memory could be defective. That said if its fitted I want it to work!
The reason was safety, probably to satisfy the U.S. market. If you came off the bike and the engine stayed running it was a fire risk or the engine could rev uncontrollably due to the carbs flooding. If the bike was down on it's left side, you couldn't turn it off as the ignition switches at the time were fitted below the front of the tank, so it gave somebody an easy way to kill the motor.
Sent from my POT-LX1 using Tapatalk
-
The orange/white and blue/white are the US front running lights, kill switch was just an easy way to stop engine without burning your fingers on the exhaust when fiddling for the ignition switch
-
You’re on the right track; you need to place the Red probe onto the B/W wire under the tank, and the Black probe onto the battery negative (or KNOWN good Earth). (Black circle in the pic). The ignition will need to be ON.
The B/W wire has two possible connectors you can use; either the one in the ‘boot’ forward LHS of the tank (Blue circle in the pic).... or by the coils where the feed splits (Red circle in the pic). (you do not need to disconnect the connectors, tho’ a slightly lower voltage reading will result)
An odd failure: my early guess is that the kill switch (or it’s wiring) has failed in the past, and the PO has simply directly connected the coils to the ignition, bypassing the kill switch circuit.
To test the Kill Switch functioning, you’ll need to disconnect both its Black and B/W connectors within the boot. (These are both within the Blue circle).
(To set the meter select the lowest Ohms range, and touch the probes together - you should see close to 0 ohms.)
Now put the probes across the Black MALE and B/W FEMALE connectors of the kill switch, and check its continuity in the OFF / ON / OFF positions. In OFF you should see Infinite ohms (open circuit), and in ON you should see close to 0 ohms.
Wiggle the handlebars / loom whilst doing this check, see if anything changes... bad loom etc.
The Kill switch is indeed a pain to remove / service. As a starter for 10 it might just be worth shooting a good squirt of WD40 into into any nearby switch orifice!
Good luck...
PS - whilst the safety implications are obvious, in this current state of ‘permanent’ Kill function ON you may burn out a coil / flatten the battery when the ignition is ON & engine not running for any length of time.
Did the first test and it gave around 11.5V.
Didn't do the second test as the b/w from the handle bar goes to a grey wire rather than another b/w. I have added 3 more labelled images which might help the expert eye.
I can see from the wiring diagram that the ignition to the horn, I think I have this in one of my images. I mention this because the horn button is missing. I opened up the left hand switchgear expecting to see remnants of the horn, however, it is completely missing, 3 cut wires bare the only evidence to its former existence. Given that these are as I understand it unavailable, I will probably be fitting a new, copy left hand switch. Correction, I was thinking of horn button, switch assemblies are available.
New images added:
https://photos.app.goo.gl/AvCtaW7HwqH5YLcx6
-
Hi again.
It would seem there’s a bit more to your wiring dilemma when you talk of cut / bare wires within the L handle bar switchgear, and really you should be considering a complete overhaul of the loom / switches as reconnecting things iaw the book may well just liven up previous cut & dangling wires.
... which was going to be my first suggestion; ie connect the loom up as designed, meaning colours can only connect to the same, and NEVER mismatched. Eg B/W to B/W, Black to Black.... NOT Black to Grey etc. If you’ve (eg) 3 Black Females floating in the headlamp bowl (wherever) and 3 Black Males, you needn’t worry where each is from / going to, you just connect them.
The above said, when checking the functioning of the Kill Switch, you DO need its specific Black feed wire as in total, there are 3 Black wires going to this RH switch gear.. ie the Kill switch, Engine Starter & Headlamp.
It’s all getting complicated - sorry. A quicker check of the kill switch might be to connect the two Black/Greys together, and also ensure ALL Blacks are connected (ie none left floating around). Then, with the Ignition ON, and VOLTAGE Scale dialed in, put the Red probe into the B/W Coil connector, and the Black probe on the battery -ve.... as you did recently. Flip the kill switch and hope to see 0V / 11.4V / 0V.
(I reiterate though. Doing the above MAY liven up some various ‘loose ends’ given your bike seems to have been badly messed with - and cause blown fuses etc)
You might be better to seek local hands-on advice?
Cheers,
Simon
-
Thanks for this Simon, some very useful information. Wiring issues often result in a can of worms opening up and it's clear I need to really dig into this issue. My plan is to completely strip the bike so currently I'm trying to fix what issues I can rather than face them during the rebuild. That said I might end up with a new loom, new left hand switch, new right hand switch etc so with that in mind I'll go as far as I can with this but if it beats me then I'll take a new tack. For example let's say I buy new handlebar switch gear I would be looking at the problem in a different way, e.g. where is the wire in the loom that I fit this wire from the switch to. Got a free day today so I'll be giving it a good look. By the way the reason I might buy a new r/h switch is because it looks like I need a new left hand one and aesthetically I would want them to match. They aren't stupidly expensive either.
-
Agreed. Often it can be a false economy to patch things that are worn out, and wiring issues especially, are notoriously difficult to fettle on a roadside.
Peace of mind is often underrated!
Good luck...
-
Disconnected both handlebar looms, removed "the bag", cleaned wires so things are clearer. Added 3 images. The first shows that the b/w from r/h switch went into a grey that connects to NOTHING. Another black connects to NOTHING. Also the thin white white wire went to NOTHING. At this point I take a mental decision to buy new l/h and r/h switch, so focus now on planning for this. With that in mind, the r/h switch loom has 7 wires, 6 male and 1 female, b/w. The main loom into which these connect are all female. The l/h switch wires all male. So the odd one out is the b/w. Presumably new switch wires will be the same, leaving me with just one issue, understanding why the b/w is female in both cases?
https://photos.app.goo.gl/AvCtaW7HwqH5YLcx6
-
Just studied the pics, it looks like the PO has removed the kill switch from the wiring as Lobo suspected. For some reason the last pic where you’ve removed all the wires from the loom you’ve left a male black/white wire still connected to a black female. Honda and most other manufacturers used plastic sleeving to cover all wires which held power, these were normally female. So you could disconnect these wires and they wouldn’t short on the frame blowing a fuse. All wires which tapped into this power were uninsulated except for a small covering where the connector was attached to the wire. So if it’s bare it’s usually dead. Now the right hand switch has a covered black/white as when the male blacks are connected it feeds the kill switch, with the switch on power comes back down the black/white hence the insulation. This should connect to the male black/white you can see in the last pic connected to the black, this goes into the loom and comes out again near the coils as a twin female, this feeds the coils, so kill switch off and no power down the black/white so no power to coils, engine stops.
Sorry if this sounds a repeat of some of the advice already given but it explains why Honda did things like this
Thanks, all observations welcome on this one. In the image where I'm wearing a glove, I left the male wire attached to the female b/w just to show how in fact it lead to nowhere. In the next image I have removed it. I still can't see how I connect the female from the switch to the female of the loom without a male to male piece for example. When I install a new handlebar switch, that is. All connections to the left handlebar switch I "get". You can see on images of new handlebar switches, they have the one b/w insulated female connector.
-
Yes, just to pint out that is where I found the wire it's not my doing! You've really helped me by focusing on this so thanks again. Looking at the wiring diagram posted by Lobo, I can see that the b/w wire in question should go directly to the female b/w wire from the handlebar switch. It's probably been put where it is to bypass the kill switch and provide a voltage to the coils regardless of kill switch position.
It has also occurred to me that the clever little wiring diagram shows the gender of the termination, triangle for male and rectangle for female. Also where rectangles are joined to each other, then that signifies a double connector.
Searching for both l/h and r/h switches, DS copies look favourite so far.
-
... these wiring diagrams are a mine of information. If you know how to use them they can save you a great deal of work.
Eg, the new LH switchgear you’ll be fitting. If needing info on what the switch operation connects to where, you’ll find that bottom LHS. It shows that the switch in LO position connects the B/Y to White, in mid position it connects B/Y to both White & Blue,
And in HI it connects B/Y to Blue.
The Horn switch. In OFF (Free) ... zip. Push it and Black is connected to Green. Slide it and Black is connected to White.
And so on.
In ‘opening up’ the loom bits and cleaning the wires you can only make your whole job easier - it’s so hard to trouble shoot when colours appear from nowhere and disappear likewise.
From what I see the basic loom looks good; but if in doubt (as you dig into it) it might be worth replacing as so much of it hidden / inaccessible once embedded into its various runs.
-
I bought a pair of switches for the 400 four a while ago, you want me to look if I still have them, genuine switches are always better than copies
Please do, where possible I am trying to keep the bike genuine without going over the top.
-
I removed the right hand switch so that I could identify the black wire from the kill switch for checking continuity with the black/white from the other side of the kill switch. Still not sure why Honda used 3 black wires rather than colours as once you've fed them through the bars you wouldn't know which was which. Anyway took enough apart to identify the 3 black wires and then test the kill switch. No continuity in any of the 3 positions. Took off the kill switch and the fault can be seen in the photo I have added. There is a shoulder of plastic next to the metal contact preventing it from touching the the 2 contacts in the switch body. It looks like it has melted at some point. I've removed this shoulder and now I've put it back together it works OK. As to whether it'll work long term I don't know. The wall either side of the contact has thinned on one side, this being where the plastic must have melted to form the shoulder.
https://photos.app.goo.gl/AvCtaW7HwqH5YLcx6
-
Well done... it’s always satisfying to find the issue. Your call (obviously!) as to whether you accept the fix, but at least if you do you now know how to facilitate a bodge to get you home. (ie connect a Black to the coils B/W!)
-
It doesnt matter about the blacks they are all power feeds to something so dont need different colours, only a problem when you get a melt like yours, which i have seen on ignition switches but never a kill switch.
-
Black signifies Ignition switched 12v.
Let alone confusing, they’d run out of options if every ignition switched 12v component on the bike used a different colour.
You don’t mention the resistance you found in the switch continuity check (after your fix) - this is significant as if high, it could lead to more melting and a false economy. If melting has occurred, it could perhaps suggest an Earth short in the B/W lead between the Kill switch and rubber boot area. Might be worth a check? (Kill Sw should be disconnected from loom, and move the loom / handlebars whilst doing so.)
A good reading will be ‘infinity’ ohms, a bad reading 0 ohms...
-
That makes sense. Just nipped out to do it, the switch is off the bike at the moment however that didn't stop me giving the wires a wiggle. Both off positions consistently giving infinity and on position giving zero.
-
You're not going to dismantle a switch and not clean the contacts.
-
I have cleaned the contacts. There is an image of them in the link above. I'm looking for dielectric grease before I reassemble the rest of the switch. Whilst I'm at it also looking for bullets, crimper etc ready for more work on the electrics. I have received a new head lamp and need to wire that in.
-
... just beware that the old Honda bullet connectors are smaller than what is commonly sold as ‘replacement bullets’. Off the top of my head I don’t know the specs.... perhaps someone can chip in with advice / best supplier here?
-
... just beware that the old Honda bullet connectors are smaller than what is commonly sold as ‘replacement bullets’. Off the top of my head I don’t know the specs.... perhaps someone can chip in with advice / best supplier here?
I think these were the ones I used 3.9 mm they do the female side as well. My old wiring loom is a bit of a mess it had the later 4.0 mm connectors in some places that had been made to fit by crushing the female side on the loom to make a contact!
https://www.ebay.co.uk/itm/Non-Insulated-Brass-3-9mm-Bullet-Connector-Terminals-Covers-Japanese-Type/332248892672?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649
-
Mac... apologies but I’m not so sure - I reckon my old Hondas use 3.5mm connectors. Smooth, obviously you’re going to have to do your homework, I’m not saying Mac is wrong, nor that I’m right! Aargh.
-
I stand corrected Lobo I am wrong you are right - I've just re-checked my old loom (again) in a few different places- it has a mixture of 3.9 mm and 3.5 mm male & female connectors!
Looking at the corrosion and insulating sleeves I think many of the originals have been replaced with 3.9 mm - a long time ago as they are green inside!
I'll be ordering some 3.5's now for when I connect the peripherals to the new loom.
-
On my first few searches e bay does not seem to list any 3.5mm connectors.
-
If you are fitting a new loom it may not have that size fitted
-
Undecided on new loom as yet. The bits I've been working on so far look good, aside from the kill switch problem and the work arounds that I've now removed, excepting there may be an underlying issue yet to reveal itself. I have found 3.5mm bullets on Amazon which should arrive soon. "Connectors,Dekaim 120pcs Brass 3.5mm Bullet Connector Terminal Male & Female with Insulation Cover". I've measured the bullets on the bike and they are 3.5mm. Just received a new crimp tool that will replace my sad looking Halfords jobby that to be fair has got me through years of odd job electrical tasks. I've moved on to another electrical task so I'll post that on my project thread. Thanks for looking for me Ted, little acts like that are so helpful when you've taken on your first bike restore than can feel a bit daunting at times. Looked down No 3 spark plug hole today and the head nut looks gruesome.
-
If you are fitting a new loom it may not have that size fitted
My loom arrived today from Electrex World Ltd - looking through the package it looks like its 3.5 mm as Lobo said - I didn't get to measure them as my wife insists it's from Santa and took it to her wrapping station. I will have to wait until the 25th December to find out.
-
That's great, I'm sure it will look like a pet snake when it's under the Christmas tree.
-
I didn't know RS sells jap bullets, that's worth knowing.