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Discussion Starter · #1 ·
Hey all,

My bike ('78 T140E) has been behaving curiouser and curiouser in the electrical department. My dad granted me this fairly pristine example from the old shed. <10,000 miles on it. He put on new rubber bits, re-did the paint, and put in a new battery (lithium ion).

All's well and I put on about 1000 miles, but my brain being what it is, I forget to turn off the headlight from time to time, and find myself recharging the battery once in a while. I'm being careful with it, not charging it for more than 15 minutes at a time. This per the recommendation of a biker battery salesman who did me the favor of charging my battery when I found myself stranded once.

But after a while I notice that the battery's not always keeping a charge. I go to test it with the multimeter and when revving it up, the volts go through the roof. (16.5 @3,000RPMs) My dad and I figure it's the zener, but it seems to be working. I put in a new battery, and the volts top out at around 13.6. However, the amps do run pretty high (9-18A @3,000RPMs), and I'm occasionally blowing a fuse (I upgraded from 20A to 30A fuses).

So, what I am wondering, is if I might be cooking the batteries. Is something wrong, or is it just the Prince of Darkness? Should I install something like this to just pre-empt things, or are those amps at the level that I should expect?
 

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A few people in the UK have used L-ion and had failures.Seems they do not like vibration or the crude regulation of these old bikes.A good quality AGM type lasts a long time.I have one on each of my old bikes and over 4 years old so far.
That regulator/rectifier will work well,just make sure that you buy the correct one,single,or,3 phase.Fit in just a few minutes as on my bike.
https://youtu.be/eLepJYCXtcs
 

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Michael


1 Please confirm your bike has a VIN between HX00100 and JX10747. This will confirm you have a 1978 T140E and not a 1979. Electrically the bikes are totally different.


2 Does this bike have the stock headlamp and is the rest of the electrical as done at the Factory?


3 I do not like the fuse problem you are having. You do not "upgrade fuses" any more than you put a penny in a fuse box to bypass a blown fuse at home. If you do not have a Brit Bike Store there go to auto parts. Ask for a Littlefuse Brand SFE20 or UK35 fuse. The original LUCAS was US rated at 17.5amps.


4 Welcome to the forum.


K
 

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Discussion Starter · #4 ·
Thanks for your replies.

My VIN is EX08096.

Yes, the headlamp is stock. None of the electricals have been replaced - to the best of my knowledge.

My dad said that a 35A fuse is what is recommended, but that is something he only recently learned. He had put a 20A fuse in, and 30A was the largest my auto parts store had in the shape that would fit. You're saying that a 20A should have been sufficient, based on original specs?
 

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Regardless of the fuse size,that Li-ion will need replacing with an AGM.The bike would run OK without blowing a 20 amp fuse unless you do have a fault .Check what has been reported about fuse size as USA has different characteristics for the fuses to the UK.
 

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Hi Michael,

Welcome to the forum.
+1.

My dad said that a 35A fuse is what is recommended, but that is something he only recently learned. He had put a 20A fuse in, and 30A was the largest my auto parts store had in the shape that would fit. You're saying that a 20A should have been sufficient, based on original specs?
You're confusing two different specifications.

GB rates specifically those original cylindrical glass-'n'-metal fuses by 'blow' Amps - hence the "35A". Otoh, the US rates them by 'continuous' Amps - half 'blow'; there isn't a 17.5A 'continuous' Amps fuse so you use 20A (or, better still on standard electrics, 15A). You should replace whatever you've "upgraded" asap.

I forget to turn off the headlight from time to time,
This sounds like an incorrect connection at the ignition switch - the headlamp should turn off with the ignition switch; post again if you'd like details of what to check - takes a newbie maybe an hour or so.

I go to test it with the multimeter and when revving it up, the volts go through the roof. (16.5 @3,000RPMs) My dad and I figure it's the zener, but it seems to be working.
With respect, if the Volts "go through the roof. (16.5 @3,000RPMs)", how can the Zener be "working"? That's what the Zener does - limit the DC Volts (to no more than 15.3V @ ~3,000~3,500 rpm).

Before condemning the existing Zener, I would check its physical and electrical connections:-

1. Remove the fuse from the Brown/Blue wire.

2. Disconnect and unbolt the Zener from its mounting on the battery box.

3. Use your meter set to resistance (Ohms, horseshoe-shaped symbol, etc.) to check continuity (~ zero Ohms) between the fuse holder and the Zener terminal, and the Red wire and battery +ve.

4. Clean any corrosion from the Zener and where it mounts on the battery carrier.

5. Reassemble with dielectric or graphite grease (not ordinary grease because it doesn't conduct either electricity or heat).

the amps do run pretty high (9-18A @3,000RPMs),
Again with respect, I don't know what you're measuring but it ain't Amps; nothing that'll physically fit inside your bike's primary chaincase is capable of generating those Amps at those rpm, and it's a specialist meter that'll measure over 10A. Standard alternator was rated for 10.5A @ 5,000 rpm and generates about 8A @ 3,000 rpm.

If the above cleaning doesn't work, regrettably, new Zeners are expensive and generally-poor quality - you might get one that works within range, but you aren't going to know that 'til you test it and many vendors often won't accept returned electrical components. :(

Time to consider a modern combined regulator/rectifier? However, certainly not that shonky Sparx one - there are definitely-cheaper-likely-better and definitely-better. What are your electrical abilities and tool kit like?

what I am wondering, is if I might be cooking the batteries.
The Zener isn't working as-is, so that'll donald any battery.

Nevertheless, as has been posted, your dad was too kind to the bike buying it a Li-ion battery; the standard charging system wasn't built for 'em doesn't really suit 'em. Check and clean the Zener but, even if it works afterwards, be prepared for the Li-ion battery to die sooner rather than later.

Hth.

Regards,
 

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Discussion Starter · #7 ·
It sounds like the arguments against the Lithium Ion battery are mounting.

GB rates specifically those original cylindrical glass-'n'-metal fuses by 'blow' Amps - hence the "35A". Otoh, the US rates them by 'continuous' Amps - half 'blow'; there isn't a 17.5A 'continuous' Amps fuse so you use 20A (or, better still on standard electrics, 15A). You should replace whatever you've "upgraded" asap.
Ah, okay, I'll do that.

This sounds like an incorrect connection at the ignition switch - the headlamp should turn off with the ignition switch; post again if you'd like details of what to check - takes a newbie maybe an hour or so.
Yes, I'd like to figure this out. As it stands, the switch on the headlamp will turn the headlamp on even with the ignition off. I do know that there's weirdness in there. I've had to open it up a couple times for sundry things, including wiggling wires to make things work right. I probably need to go through it and check to make sure all the connections are seated properly, but the headlamp going off and on with the ignition switch off has been a constant.

With respect, if the Volts "go through the roof. (16.5 @3,000RPMs)", how can the Zener be "working"? That's what the Zener does - limit the DC Volts (to no more than 15.3V @ ~3,000~3,500 rpm).
Regarding the zener, what I did was put an ammeter between the zener and its wire. When I was conducting the test with the old battery, it showed that current was flowing through it. I was also watching the volts over the battery with my multimeter. They would both fluctuate rather wildly, but both went up as I revved the engine. I did the same with the new battery and the volts were limited and current flowed through the zener.

To do the test properly, should I have been watching the volts over the zener instead of the battery?

Before condemning the existing Zener, I would check its physical and electrical connections:-

1. Remove the fuse from the Brown/Blue wire.

2. Disconnect and unbolt the Zener from its mounting on the battery box.

3. Use your meter set to resistance (Ohms, horseshoe-shaped symbol, etc.) to check continuity (~ zero Ohms) between the fuse holder and the Zener terminal, and the Red wire and battery +ve.

4. Clean any corrosion from the Zener and where it mounts on the battery carrier.

5. Reassemble with dielectric or graphite grease (not ordinary grease because it doesn't conduct either electricity or heat).
I'll give those a shot, though I'm wondering about the grease. It bolts onto the airbox. Where would the grease come in?

Again with respect, I don't know what you measuring but it ain't Amps; nothing that'll physically fit inside your bike's primary chaincase is capable of generating those Amps at those rpm, and it's a specialist meter that'll measure over 10A. Standard alternator was rated for 10.5A @ 5,000 rpm and generates about 8A @ 3,000 rpm.
Well, I'll admit that I'm very new to this. I'm reporting what I saw. Perhaps I should try it again and make double sure that the meter is set to the right settings. I generally don't do anything right the first time, and I was doing this together with someone else, so perhaps his meter was set wrong. (Mine was checking the volts over the battery - not to blame him, but I wasn't working his device during this process.) :unsure

If the above cleaning doesn't work, regrettably, new Zeners are expensive and generally-poor quality - you might get one that works within range, but you aren't going to know that 'til you test it and many vendors often won't accept returned electrical components. :(

Time to consider a modern combined regulator/rectifier? However, certainly not that shonky Sparx one - there are definitely-cheaper-likely-better and definitely-better. What are your electrical abilities and tool kit like?
My capacities are very modest, but I learn and figure things out. Any tools I don't have I can get from a Harbor Freight for cheap. (It's where I got the higher-end multimeter.) If the video posted by Rambo above is anything to go by, it doesn't look all that difficult to me. I can solder stuff if need-be.
 

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The video of the Podtronic type unit shows how it just connects to existing rectifier wires.If you buy one,it generally states connect to the battery positive and negative but going through the ignition switch will cover it with a fuse if a fault develops in the unit.Once fitted,just disconnect the wire that goes to the zenor,it is not needed.
 

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I will defer to Sir Stuart :wave and not duplicate what has already been said :applause. I wanted to confirm you in fact had a 78 T140 which is a POSITIVE ground vehicle. A small bits of info for you as far as the charging system.

1 With the stock headlamp on the battery is not charging until you reach about 2400RPM.

2 On my 78 T140V (NX010XX) if the battery goes flat I am able to start and ride the bike. First you remove the fuse so all power is diverted to the ignition. After starting replace the fuse so the battery may charge. A personal thing is I remove the fuse on my Brit Bikes when parking for the evening or winter storage.

3 A defective Zener Diode may or may not blow the fuse. I have seen both happen. If you do have a Zener go bad and the bike stops and will not start unplug it. Assuming that was the problem the bike will now start. You will be able to proceed at REDUCED RPM's. Remember you have just removed the 'voltage regulator' from the system.


4 Not saying you will have a problem but I have seen problems with the handle bar kill switch. If it goes bad bike will not run. Just something to be aware of.


5 SFE20 fuse was recommended due to its blow characteristics. UK35 would be preferred. Of the SFE style fuses only the 20 is the size to fit the stock fuse holder. While there are other fuses that size with ratings above and blow 20 they blow at a different rate.


6 I would not go spending money on part until it is determined what the problem is. Among other things as the bike has sat for a bit corrosion at terminals also misconnected items as some disassembly was done.


All my bikes have completely stock electrical systems and we get along fine. You first have to learn how it works and stay in the parameters. Many Lucas parts were not designed for motorcycle specific use but they do perform admirably. Other brand bikes have problems Old Yamaha XS650's used to 'eat' Alternator brushes and older Honda 750 had charging problems when the headlamp on laws came into effect among others.


K
 

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Hi Michael,

I forget to turn off the headlight from time to time,
This sounds like an incorrect connection at the ignition switch - the headlamp should turn off with the ignition switch;
You'll need to undo the headlamp shell from the fork mountings, so you can get access to the wires connected to the ignition switch.

However, first have a look inside the headlamp shell, confirm that the toggle switch has either "31788" or "35710" either moulded into the plastic case or stamped on a metal part, and a Brown/White(?) wire is attached to either terminal #1 or terminal #4 (the numbers are very small and moulded into the switch case).

Turning to the ignition switch:-

. when you pull the rubber 'boot' off the back of the switch, you should see three wires (Brown/Blue, White and Brown/White (? - same colours as connected to toggle switch terminal #1 or #4);

. on the back of the switch should be three or four male spade terminals - if three, one physically-connected pair and a separate single rivetted to the switch; if four, two physically-connected pairs rivetted to the switch);

. the White wire and the Brown/White(?) should be connected to the same physically-connected male spade pair, the Brown/Blue wire should be connected on its own to either the single spade terminal or one of the other physically-connected pair;

. Brown/Blue is the supply from the battery; the idea is that it's connected to the White wire and the Brown/White(?) to the lights toggle switch only when the ignition switch is turned to 'on'. :thumb

Regarding the zener, what I did was put an ammeter between the zener and its wire. When I was conducting the test with the old battery, it showed that current was flowing through it.
By definition, it should not have been all the time.

The comprehensive test procedure for the standard Zener fitted to your bike is detailed in the Triumph workshop manual for your bike, manual page H13, .pdf page 182. It says that the Zener should not conduct at all below 12.75V.

However, as I say, no alternator produced by Lucas is capable of generating the "9-18A @3,000RPMs" that you saw; even if one were, you cannot have a variation of 9A at the same rpm.

I was also watching the volts over the battery with my multimeter. They would both fluctuate rather wildly,
Harbor Freight
where I got the higher-end multimeter.
My understanding from several posts over the years on the BritBike forum is Harbor Freight meters are not protected from external emi (electro-magnetic interference). When your bike's engine is running, emi is generated by the HT. 'Fraid that would account for a lot of the nonsense your meters are showing, which renders them useless as diagnostic tools. :(

To do the test properly, should I have been watching the volts over the zener instead of the battery?
Doesn't matter where you watch it, the system has (should have) the same Volts everywhere.

The usual and simplest Zener test is to connect a Volt-/multi-meter across the battery, observe the indicated Volts with everything off (~12.5V~13V), ignition on (a little less), engine running. With engine running, increasing the rpm slowly should see Volts rise with rpm to ~15V @ ~3,000~3,500 rpm, stay at that level even if engine rpm rises higher, only reducing when rpm reduces below that limit. While by no means completely comprehensive, that is a good indication the Zener is :thumb

Before condemning the existing Zener, I would check its physical and electrical connections:-
5. Reassemble with dielectric or graphite grease (not ordinary grease because it doesn't conduct either electricity or heat).
I'm wondering about the grease. It bolts onto the airbox. Where would the grease come in?
The grease simply excludes the possibility of corrosion-causing moisture between the Zener itself and its airbox and Red wire connection to battery +ve. Dielectric or graphite grease conduct electricity and heat, ordinary grease doesn't.

I generally don't do anything right the first time,
No worries, we all have to start somewhere. :) However, as I say, not only is neither the standard alternator fitted to your bike nor any alternator Lucas made capable of fitting into the physical confines of your bike's primary chaincase capable of generating 18A @ 3,000 rpm, you cannot have a variation of 9A at the same rpm, the first suspect when a meter gives impossible readings is emi, and Harbor Freight meters are notoriously not protected against emi. :Darn Btw, you don't need a "high-end" meter for emi protection, even the cheap one I carry on the bike has it ...

What are your electrical abilities and tool kit like?
If the video posted by Rambo above is anything to go by, it doesn't look all that difficult to me.
:thumb

The two commonest types of terminal on your bike are bullets and spades. Bullets specifically require a crimping tool with a half-hex in each jaw, spades require a 'M'-shaped cut-out in one jaw. Don't know whether these are available from Harbor Freight but they're definitely available from British Wiring (TT85 and PR4 respectively). However, I appreciate that you might find BW's prices expensive, I can point you at British suppliers who not only have those but cheaper tools.

The video of the Podtronic type unit shows how it just connects to existing rectifier wires.If you buy one,it generally states connect to the battery positive and negative but going through the ignition switch will cover it with a fuse if a fault develops in the unit.
Sorry, 'fraid this is A Bad Idea.

As I posted above, Lucas rated the standard alternator for 10.5A @ 5,000 rpm and ~8A @ 3,000 rpm.

Asking the ignition switch contacts to transmit these sort of Amps just to save the cost of a common automotive blade fuse and holder in one of the wires between reg./rec. and battery is not sensible.

If you decide to upgrade the alternator in the future, the arrangement makes even less sense.

Hth.

Regards,

'Mornin' K, :)
 

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The wiring for your bike is the same as my T120V.
If you stop/break down at night, you must show a red light to the rear and a white light forwards...in the UK anyway.
This is provided by the pilot light switched ON, with the ignition switch on or off.
Toggle switch lever pointing up.
There is a brown/blue to pin 4 of the light switch from the -12V side. (maybe ign sw., zener or bridge rectifier - terminal.)
But the headlight needs the ignition on, as it would drain the battery quickly if left on with the ignition.
 

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Hi Caulky,

My bike ('78 T140E)
The wiring for your bike is the same as my T120V.
No, it isn't.

There is a brown/blue to pin 4 of the light switch from the -12V side.
Only if someone's been screwing around with the electrics on Michael's bike. As standard on a '78 T140E, there isn't.

the headlight needs the ignition on, as it would drain the battery quickly if left on with the ignition.
That's why I've suggested that Michael arranges the connections on the ignition switch so that it turns the headlamp on and off as well.

Hth.

Regards,
 

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Don't bikes of that age in the USA have to have lights on all the time? Hence the different wiring for North America?
 

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Don't bikes of that age in the USA have to have lights on all the time? Hence the different wiring for North America?


I believe that started with 1978 model year. But some earlier US bikes also had different wiring for other reasons.


K
 

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Hi Dave,

Don't bikes of that age in the USA have to have lights on all the time? Hence the different wiring for North America?
FMVSS reg. effective 1st January 1978. Along with the other reg. effective on the same date mandating lower emissions, that required the Mk.2 carbs. on the parallel-port head with the revised frame oil tank and crankcase venting into the airbox.

Regards,
 

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Regarding the old parking/sidelight arrangement.I took out my front side light as it is not an MOT requirement.This allowed me to fit a different halogen light unit.Later,i connected a day riding LED under the headlight and i get seen by the cars now.Of course,like a lot of parts,i change things around so running a concave Cibie light with old tungsten lamp now.Not very bright but it looks good ! There are some lower wattage halogens available to fit the old lampholders now and bought one for the original looking BSA.Its about 40 watt.Generally,i do not go out at night due to all the wildlife trying to knock me off.Worst type are the wild deer but have had encounters with cows,horses and sheep getting on the road.Had one encounter with a horse and the car overturned.Another incident with a car hitting the back legs of a cow which sat down and squashed the front end down quite a bit .Several bike riders have been killed within 4 miles of my house by the wild deer at night.
 

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Discussion Starter · #17 ·
Okay, it seems like I have my homework cut out for me.

I just wanted to take the quick moment to thank you all for your replies and help.

I'll probably respond to other aspects later, as I investigate further, but here's what I have time for:

My understanding from several posts over the years on the BritBike forum is Harbor Freight meters are not protected from external emi (electro-magnetic interference). When your bike's engine is running, emi is generated by the HT. 'Fraid that would account for a lot of the nonsense your meters are showing, which renders them useless as diagnostic tools. :(
I guess I'll have to make a tin-foil hat for my multimeter - or at least situate it further from the bike when running diagnostics. I already feel like I have to be Vishnu for some of these tests, but it keeps it interesting.

No worries, we all have to start somewhere. :) However, as I say, not only is neither the standard alternator fitted to your bike nor any alternator Lucas made capable of fitting into the physical confines of your bike's primary chaincase capable of generating 18A @ 3,000 rpm, you cannot have a variation of 9A at the same rpm,...
Yeah, I'm guessing my reading was just faulty then, but if I'm burning up these fuses, doesn't that indicate that at times I am running that sort of high current - which is causing the burnouts? That's not an alternator capacity issue, but a shorting-out fault.

When I get a moment I'll be running the tests again, and will report my findings.:nerd:
 

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Hi Michael,

if I'm burning up these fuses, doesn't that indicate that at times I am running that sort of high current
I don't mean to be rude but repetition is becoming tedious:-

. The standard alternator fitted to your bike is simply not capable of generating the 20, 30, etc. Amps to blow fuses of those ratings. Even when brand-new, it generated around EIGHT Amps @ 3,000 rpm.

. Even if a p.o. had upgraded the alternator to the most powerful capable of being fitted inside the chaincase without obvious external modification, it will only generate about 12.5A @ 3,000 rpm.

. For your bike to be generating 18A @ 3,000 rpm, it would have some huge alternator likely mounted in front of the engine with an external belt drive through one or more big holes into the engine. And the wiring would be either melted standard wires or thick fat ones.

If your bike has such obviously-major modifications, it would've been helpful if you'd mentioned them before?

Otoh, the other far-more-likely reason for blowing large-Amp fuses is you have a 40-year-old bike - with 40-year-old wiring? - that often wasn't assembled with the greatest care. Any battery is quite capable of generating 100A through a short-circuit for the milliseconds necessary to blow a fuse. That's why the wiring has at least one fuse.

Hth.

Regards,
 

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Follow every wire and check inside the headlight unit,the lampholders and you might find a wire contacting the frame or case.Wires might also chafe through where in a tight fitting area.You might find the short circuit this way.Inspection is the best tool.
 

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Gentlemen

Regarding the Headlamp/Parking lamp question. Since about 1976, on US bikes, the pilot bulb is wired to the headlamp bulb. When the headlamp is on the pilot bulb is on. It cannot be operated by itself.. By reviewing the 1978 T140E parts supplement there is reference to a diode pack used for headlamp on.


Michael

To see parts book for your bike www.vintagebikemagazine.com Use both the T140V(#99-7003) Book and T140E (#00-7003) Supplement Book.

For a wiring diagram use the Service Manual link Stuart posted earlier. Use the one on page H22, but be aware this one does not show the diode pack mentioned above. Nor is it shown correctly in the T140E Owners Manual(www.classicbike.biz).

As previously suggested by others I am of the opinion you have a dead short somewhere in the system. Possibly caused by a defective part, incorrect wiring, a bare wire grounding out, or combination of these. If it was me first thing I would do is compare the diagram to how your wires are connected at the same time looking for any bare, frayed, or rubbing wires. Look also for a common theme in when the fuse blows. Such as handlebar being turned to the right or left, hitting a bump etc. I have a bike, when it was new, used to shut off when riding. I noticed it occurred when the handlebars were moved just so. Played around and found out (saw sparks under the gas tank) clutch cable was rubbing against the coil and grounding out the ignition. Before you ask the problem bike was a Yamaha.

One other thing take care of the Styling panels on your bike. They are not the same as those on the T140V and to the best of my knowledge are not being reproduced..


K
 
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