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Discussion Starter #1
Good afternoon to all.
The last time I rode the cub it kept cutting out. It would kick start again and then after a few miles cut out again. So I have now over the last few weeks changed all the electric connections to soldered ones as opposed to bullet type. I have also stripped down the fuel system eg emptied, flushed and refitted tank, stripped carb and cleaned it and put it all together. I proceeded to then start it and she awoke on first kick. After warming up and running for about 5 mins it stopped. From that point it will not start again. I’ve got compression, spark and a full 12.58v from battery. Fuel is getting through to carb so no blockages.

Any ideas as I thought the work I did would have sorted it out but alas it appears the initial problem is still there and I’m flummoxed ?

Any help really would be appreciated

Cheers
Stu
 

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condenser?
Have you tried a spray of staring fluid? That would help identify if it's fuel or electrics.
Standard road wiring?
 

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Discussion Starter #3
Hi Dave, I’ll give that a go tomorrow.
It doesn’t have a condenser as it’s now a 12v system.
Thanks and hopes that works.
Any ideas why it just stops after a while?
Stu
 

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Coil could overheat?
Runs out of fuel because the float sticks?
Petrol cap breather blocked?
Partial seizure nipping up/cooling down?

Are you sure that you don't need a condenser with 12v?
 

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Discussion Starter #5
Hi Dave, because it a converted 12v electrical ignition I lost the condenser. Not sure how to test the coil to see if that’s ok. Happy that the float doesn’t stick but will check breather hole in cap just in case. It’s just weird how when it does actually start and running nicely it just cuts out.
Stu
 

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Sounds like a coil to me, they work fine cold, but stop when hot. This sometimes happens if there is a hole in the coils alloy and all the coolant oil has leaked out.
 

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Discussion Starter #7
Thanks Trindent, will take it off and have a good look.

Cheers
Happy to try anything at moment.
Stu
 

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Hi Stu,

converted 12v electrical ignition
I guess you mean "electronic ignition"? :) 12V coil switched by points would still be "electrical" but it'd still need a condenser.

Which electronic ignition? It would've been helpful to mention this in your first post as what you described:-

kept cutting out. It would kick start again and then after a few miles cut out again.
awoke on first kick. After warming up and running for about 5 mins it stopped. From that point it will not start again.
weird how when it does actually start and running nicely it just cuts out.
... is classic electrical fault symptoms:-

they work fine cold, but stop when hot.
... can apply to anything electrical.

Not sure how to test the coil
If you don't have a multi-meter, beg, steal, borrow or buy one.

If you have a meter, set it to Ohms (might be indicated by the Omega horseshoe-shaped symbol):-

. One meter lead on each coil LT terminal, meter should display between 3 and 4 Ohms (a modern pattern '12V' coil could display up to 10% more); outside the range, the coil is donald (much lower and 'fraid it could've taken the EI with it :().

. Assuming the LT check is within range, one meter lead in the HT terminal, other meter lead on each LT terminal in turn, meter should display ~5,000 Ohms (if the meter auto-ranges, it could display just "5" but check this is KiloOhms). Post anything apparently vastly different and we can tell you if it's still OK.

. Assuming both above checks are within ranges, one meter lead on the casing, other meter lead on each terminal (LT and HT) in turn, meter should display a very high number (some meters display the infinity symbol - looks like an "8" on its side).

If the coil passes the checks cold, you'll be wise to do them again if the bike conks out when warm. However, post the EI details, I'll advise some checks I'd make to one of those too.

Hth.

Regards,
 

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Discussion Starter #9
Hi Stuart, tested the coil and when one lead into ht and the other on either terminal the reading was 9.10. When I tried to get a reading from frame and ht connections there was no reading coming up. The only reading I could get on the ohms was. With ht and either terminal and always 9.10.
The system is a PBOXOO108 Boyer single phase power box alternator regulator with seperate single phase rectifier so no points, condenser etc. HT lead gives a constant reading of 11.8.

Regards
Stu
 

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Hi Stu,

tested the coil and when one lead into ht and the other on either terminal the reading was 9.10.
If you're absolutely sure you tested it exactly as I described in my previous post, doesn't sounds right - if it's KiloOhms, that's almost double what it should be; otoh, if it was plain Ohms, it's wa-aa-ay too low. What make is the coil?

What's the Ohms reading between the coil's LT terminals?

When I tried to get a reading from frame and ht connections
This doesn't make any sense. HT is only between the coil HT terminal and the spark plug.

Inside an ignition coil are two windings (coils of wire), LT and HT. On your bike (most old vehicles) the LT windings are powered by the battery when not disconnected by points, electronic ignition or kill switch or ignition switch. The LT windings charge the HT windings by magnetic induction (there always being a magnetic field around a wire with electricity passing through it). When power to a coil's LT windings is switched off (by points, electronic ignition, kill switch, ignition switch, etc.), the magnetic field collapses, triggering a discharge of the energy in the HT windings, which (usually) becomes a spark at the plug gap.

In a coil with only one HT terminal, the other end of the HT windings is connected to one of the LT terminals. When the meter's set to Ohms and you put one meter lead in the coil HT terminal and the other meter lead on each LT terminal in turn, you're testing the resistance of the coil's HT windings, which is about 5,000 Ohms (5 KOhms) in an 'original Lucas' coil. That's why I've asked you for the make of the coil, patterns made by PVL, Wassell ("Genuine :LOL: Lucas") can have a different HT resistance. But 9,100 Ohms ("9.1" KOhms) is likely too high. :(

However, I do not understand why you're trying "to get a reading from frame and ht connections", the HT is never connected to the frame.

is a PBOXOO108 Boyer single phase power box alternator regulator with seperate single phase rectifier so no points, condenser etc.
Errrm ... you're really, really confused ...

Any Powerbox is a combined regulator and rectifier - look at the fitting instructions - its input is from the alternator, its output is 12V DC; the input is Alternating Current, the output is Direct Current, this cannot be if the Powerbox doesn't rectify. Also look at the wiring diagram, where does it show a "seperate single phase rectifier"?

Powerboxes only convert alternator AC to DC; none do ignition. Again look at the wiring diagram; "IGNITION UNIT BOYER" (connected to two separate "6V COIL") is completely separate from "POWER BOX BOYER".

If you're using a Boyer-Bransden electronic ignition, an educated guess says either a Black or Red "IGNITION UNIT"; if that's labelled with a black-printed silver label, it'll say respectively "MicroMark" plus Roman numerals or "MicroDigital" (if the Box is Blue and labelled "MicroPower", you're really up sh1t creek because they work differently and don't use points-type ignition coils).

Btw, as your bike's a single, you are using a single '12V' coil, not a "6V" shown in the PBOXOO108 wiring diagram?

HT lead gives a constant reading of 11.8.
This is with the meter set to Ohms, one meter lead attached to one end of the HT lead, other meter lead attached to the other end of the HT lead (not the plug cap)? If so, sounds like it's a resistive HT lead; why did you fit that?

Hth.

Regards,
 

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A 61 cub has the points in the distributor type housing. Is this standard, or does the bike have the EI that uses the points as the trigger? Another type uses a circuit board inside the unit.
 

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Discussion Starter #12
Wow, thanks for your info Stuart. I think I need to have a really good look at the wiring as I’m somewhat confused at what I actually have installed and what you have listed I should have including why I have a seperate rectifier.
In answer to some of your queries I can say:
I think I tested in ohms not kilo ohms so will try again on correct settings.
It’s a Wassell 12v coil.
I will double check the power box and wiring against the instructions and come back to you once done.
My head is spinning to take on everything you have stated above and as I need to get the bike going I am going to take each one of your comments and check it against what I actually have as the more I read the more I think something is majorly wrong!

Thanks again for all the comments and I will return in a few days after checking numerous electrical items.

Regards
Stu
 

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Discussion Starter #13
Ok Stuart, looking at what I’ve actually got I think I have misled you all. I have a Boyer Macro MK 1V high powered ignition unit for BSA/Triumph single. This is what was fitted when it was converted to 12v. 095EC4EE-45EB-4BFC-9E2C-B58E6BFCAE42.png
This is why I have the rectifier.
The coil is a 12v Wassell version.
I could not see kilo ohms on my meter just ohms. The reading from ht socket on coil and other lead on either terminal tonight was 8.7 a drop from last night.
I’m hoping this info gives you a better idea as to what may be wrong.
Stu
 

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Hi Stu,

have a Boyer Macro MK 1V high powered ignition unit for BSA/Triumph single.
:) No worries. Note for the record, there isn't anything "high powered" about it, it's essentially just an electronic version of the original points and auto-advance, so just still a glorified on-off switch.

This is why I have the rectifier.
Uh-uh. As I wrote in my earlier post:-

. The Powerbox is a combined regulator and rectifier, it must be because its input is alternator AC, its output is DC.

. Look at the Powerbox wiring diagram, do you see any additional separate rectifier shown? :) You aren't achieving anything by having any separate rectifier connected.

coil is a 12v Wassell version.
could not see kilo ohms on my meter just ohms. The reading from ht socket on coil and other lead on either terminal tonight was 8.7 a drop from last night.
Hmmm ... for the time being, assume your meter is auto-ranging (changing ranges automatically because the digital display itself can't show "8,700" (or 9,100 earlier)).

hoping this info gives you a better idea as to what may be wrong.
More things to check and eliminate as possibilities for the fault(s):-

In all the following advice, I've assumed your bike's electrics are standard 'positive earth'.
If your bike's been converted to 'negative earth', post and I'll amend the relevant parts of this post.​

. Any additional "separate rectifier" - as above, should be disconnected (and removed?):-

.. Originally, the alternator White/Green (or Light green) and Green/Black (or Dark Green) wires were connected to different rectifier AC terminals, these should've been connected to different Powerbox Yellow wires when the Powerbox was fitted.

.. At best, the Powerbox Black wire could've been connected to the original rectifier Purple wire to ignition/lighting switch terminal 13. I might consider this only on a bike with an Ammeter. If your bike doesn't have an Ammeter, the Powerbox Black wire should be connected directly to the battery -ve terminal and any wire connected to ignition/lighting switch terminal 13 discarded.

.. Or post a picture of the component you're calling a "separate rectifier", in case you've mis-identified it?

. Coil - please post the Ohms readings:-

.. between the coil's LT terminals (as it's a Wassell coil, between 3 and 4.4 Ohms would be good);

.. between each coil terminal (HT and both LT) and the case, very high numbers would be good.

. Does the wiring loom contain Red wires, that connect (say) the headlamp or shell and the original rectifier frame mounting to the battery +ve terminal? If so, on the electronic ignition:-

.. The Red wire from the "Transistor Box" is attached to the battery +ve terminal itself (contrary to the fitting instructions, not to the frame or any other part of the bike)?

.. The Box Black wire is attached to the coil's "-" terminal?

.. The (Red?) wire from the coil's "+" terminal is either attached to the battery +ve terminal itself or connected into the Red wires on the bike already (again, contrary to the fitting instructions, not to the frame or any other part of the bike)?

.. There is a Red wire from the bike's wiring loom attached to an engine component?

. Also on the EI:-

.. Please post how particularly the Transistor Box Black/Yellow wire has been connected to the EI "Stator" (where the points and mechanical auto-advance used to be) Black/Yellow?

.. Bransden chose Black/Yellow (and Black/White) because Lucas used these to wire colour combos. to connect coils and points on twins and triples, his Stator replaced the points so Bransden used those wires to connect his Stator to his Box.

.. However, when used to connect EI components, those wires and connections must be near-perfect. Your bike had only the Black/White wire and its connections originally so how good they and any Black/Yellow connections are is important.

.. Temporarily disconnect the EI Stator Black/White and Black/Yellow wires, set your meter to Ohms and hold each meter lead on a different Stator wire terminal; the meter reads 136 Ohms?

. Turning to the rest of the bike's electrics, as it's been converted to 12V:-

.. The alternator Green/Black (or Dark Green) wire is connected only to one Powerbox Yellow wire; it isn't still connected to terminal 7 on the ignition/lighting switch?

.. Similarly, the alternator Green/Yellow wire is connected only to the same Powerbox Yellow wire as the alternator Green/Black (or Dark Green) wire; the Green/Yellow isn't still connected to terminal 16 on the ignition/lighting switch?

.. The Black/White wire isn't still connected to terminal 15 on the ignition/lighting switch?

.. Is there a fuse in any wire connected to either battery terminal? If there is:-

... If it's a modern automotive blade type, have you pulled the fuse out, inspected fuse and holder terminals for any obvious corrosion, scrubbed the fuse terminals with a brass wire brush then pushed the fuse back into the holder and pulled it out a few times, to ensure there's good contact between fuse and holder terminals?

... Otoh, if it's a cylindrical holder and fuse, have you taken the holder apart, extracted the fuse, pushed the parts of the holder down each wire so the terminals are accessible, scrubbed the ends of the fuse and the wire terminals with a brass wire brush and reassembled?

... In either case have you considered replacing the fuse with a 'known good' one (fuses are cheaply made and can suffer from vibration)?

Unless any of the above checks show up an obvious fault, before trying another test ride, prepare a test wire that'll connect the electronic ignition directly with the battery:-

. Assuming standard 'positive earth', the wire should reach from the battery -ve terminal to the White wire terminal on the Boyer-Bransden Transistor Box.

. The wire should be long enough to loop out from under the seat, this loop should have a fuse holder and the loop/holder should be positioned where you can access it easily sitting on the bike. Reason is, when the EI's connected to the battery with this wire, the only way of stopping the engine is by pulling the fuse in this wire.

. I'm assuming the Box White wire terminal on your bike is the male spade shown in your picture? And the White wire from ignition/lighting switch terminal 14 has a corresponding fully-insulated female spade terminal? If so, your test wire will also need a fully-insulated female spade to connect to the male spade on the Box White wire.

. The test wire can be attached to the battery -ve terminal. However, don't connect the wire to the EI Box and carry the fuse in your pocket. Only if the bike stops on the test ride, immediately disconnect the Box White wire from the ignition/lighting switch White wire, connect the Box White wire to the test wire, fit the test wire's fuse and see if the engine will restart. If it does, you know the problem is somewhere in the standard wiring between battery -ve and the ignition/lighting switch White wire, because that's what the test wire has bypassed. (y)

. Otoh, if the engine won't restart, while you haven't eliminated the possibility of problems in the standard wiring, there's also at least one problem in the EI wiring. (n)

Also take your meter with you on the test ride (hopefully the meter's one that'll fit in a jacket pocket). Especially if the engine won't restart even after connecting the test wire, repeat the earlier coil tests - between the LT terminals, between HT terminal and each LT terminal, between case and each terminal - as @tridentt150v intimated earlier in the thread, you're looking for big differences in any reading between the coil cold and warm/hot.

Hth.

Regards,
 

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Is the bike a road bike or a trial one?
Is the alternator original (6v converted to 12v) or replacement?
If trials is it wired with simplified switch gear, mountain cub style, or retain the PRS8 switch?
 

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Discussion Starter #16
Thanks Stuart, plenty to have a look at. The bike is a positive earth as you correctly assumed. I will get a picture uploaded of what I’m calling the rectifier as this is the only piece that has the yellow wires to connect to the alternator. I will write down how the macro 1V box is connected and the “rectifier” and let you know as the more I read your response the more I’m wondering if I’ve miss wired the PRS8 switch as I used the wiring diagram from the incorrect power box I first thought it was!!

Regards
Stu
 

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Discussion Starter #17
Is the bike a road bike or a trial one?
Is the alternator original (6v converted to 12v) or replacement?
If trials is it wired with simplified switch gear, mountain cub style, or retain the PRS8 switch?
Hi Dave, it’s a road model T20. The alternator was a replacement 12v with 3 cables. It runs with the original PRS8 switch albeit I may have taken out certain links that were original thinking I was wiring up to the wrong power box.
Stu
 

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Hi Stu,

it’s a road model T20.
what I’m calling the rectifier as this is the only piece that has the yellow wires to connect to the alternator.
The Boyer-Bransden Powerbox should have two Yellow wires to connect to the alternator (stator) wires. You posted earlier it's a PBOX00108, the fitting instructions have a picture of what that looks like, including the details on its black-printed silver label.

Rectifiers


Separate rectifiers look like the ones in the picture. The one on the left is the Lucas 47132 listed in your Cub parts book; it's 6V and afaict selenium. The one in the middle is 49072, fitted to all 12V Britbikes, has diodes. The one on the right is a common Chinese-made aftermarket, been around for decades, the good ones were (are still?) good but they have to be made so cheaply to be cheaper than combined reg./rec. that there many bad ones.

Either of the 12V ones would be used with a Zener for regulation.

alternator was a replacement 12v with 3 cables.
For clarity, alternators aren't either "6V" or "12V", they produce AC.

Afaik, all the British automotive electrical parts suppliers (certainly Lucas and Wipac (Wico-Pacy)) supplied all the British motorcycle makers with 'permanent magnet' alternator rotors. Then AC Volts depend only on the rotor rpm and the consumers (ignition coils, lamps, etc.) being supplied, aka the "load" across the stator coils.

"6V" and "12V" refer only to common automotive nominal regulated DC Volts. Before Lucas supplied Zener diodes for regulation ('64-on 6T, '66-on other Triumphs), DC Volts were regulated by the attached battery and some complicated switching of alternator stator coils by the ignition and lighting switches.

Aside, one of the reasons nominal regulated DC Volts went from 6V to 12V with Zeners was only 12V Zeners were available at the time.

alternator was a replacement 12v with 3 cables.
Regrettably, doesn't mean a lot; the more important difference is whether the rotor is original 70 mm. or '62-on 74 mm. OD.

'61 Cub would've been fitted with a 70 mm. rotor originally; if it still has this, the stator cannot be any later than a RM18. That and earlier were originally regulated to a nominal 6V DC; none were very powerful (didn't produce many DC Amps) if regulated to 12V, they produce even fewer DC Amps. :(

Otoh, if the rotor has been replaced with a later 74 mm., "3 cables" mean RM19 or RM20 single-phase or RM24 3-phase. If the original rotor has been replaced with later, given all the other problems, I strongly advise you to verify the stator:-

. if the stator isn't encapsulated - you can see the six coils of copper wire - not only is it old but also prone to failure - the later encapsulation shielded the wires from vibration; however, at least you'll know it's single-phase;

. if the stator is encapsulated and you can find a 5-figure number on it, 47204 = RM19, 47209 = RM20, 47244 or 47252 = RM24;

. if you can't find the stator's 5-figure number, look inside its centre and you'll see a number of metal squares - the ends of the wire coils' cores - 6 = single-phase, 9 = 3-phase.

Aside, RM19 was fitted certainly to the twins '62-'68; as I say, electrics changed from 6V to 12V (DC) '64-'66. So the same RM19 alternator was regulated to both 6V and 12V DC.

original PRS8 switch albeit I may have taken out certain links that were original thinking I was wiring up to the wrong power box.
The PRS8 switch itself never had anything to do with fitting a Powerbox. The only wiring that should've been taken out was some attached to PRS8 terminals:-

. The Black/White wire between PRS8 terminal 15 and the ignition coil "+" terminal.

. The wire between PRS8 terminal 7 and one of the alternator wires (either Dark Green or Green/Black).

. The alternator Green/Yellow wire must be detached from PRS8 terminal 16. This wire must be reattached elsewhere, where exactly depends on whether the alternator stator is single- or 3-phase.

. Assuming your bike doesn't have an Ammeter, the Powerbox Black wire should be attached directly to the battery -ve terminal; you should then be able to detach and remove the (originally Purple) wire attached to PRS8 terminal 13; however, this'll only work if the link between PRS8 terminals 2 and 12 is still present?

. If I'm mistaken and your bike does have an Ammeter, post the wire colours attached to each Ammeter terminal and I'll advise where to connect the Powerbox Black wire.

will write down how the macro 1V box is connected
Just as an aside, it's a "Micro" - as in "very small" - and "IV" - as in the Roman numerals for "4". ;)

Hth.

Regards,
 

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Discussion Starter #19
Good evening all, well this time before I did anything I found amongst my emails 3 years ago the one that Boyer sent me after I’d purchased the power box I now have and I found out that it wasn’t any of the ones I stated as I couldn’t actually see the one fitted so wrongly assumed which one it was. So now I know and have attached a photo of what I called the rectifier and the fitting instructions Boyer sent to me at the time. I’m hoping once you see what I’ve actually got it may make more sense.
I can only apologise and hope you can still help with my original problem.

087271EB-B014-44CC-9A29-48C041309184.jpeg

5D813768-DD7E-4729-B8C8-693008416B55.jpeg


Regards
Stu
 

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Hi Stu,

I can only apologise
:) No need. The "Powerbox" reference you posted earlier was for a 'normal' one (i.e. not one of the more complicated ones that does lighting, etc.). The image in your post above is for a common regulator/rectifier, just not an actual Boyer-Bransden Powerbox.

So all the advice I posted earlier in the thread applies exactly the same, including connecting the reg./rec. Red and Black wires directly to the battery +ve and -ve terminals respectively. There isn't anything gained - but ime much to be lost - by connecting the reg./rec. Red wire to some random bit of bike and the reg./rec. Black wire to a sixty-year-old electrical switch.

Hth.

Regards,
 
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