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Fifty-plus years on, it's hard to know the real reason for four condensers (two on the points plate and two external), possibly simply to save scrapping a large number of 4CA points plates? Once the 4CA was superseded by the 6CA, there are only the two external condensers; as "Magnetoman" explains, not such good protection for the points but, given the external condensers' increased longevity, that the points were protected for longer was considered an acceptable compromise?
Triumph/Lucas would have known the implications of adding condensers at the coils and would have been aware that the amount of capacity needed to suppress sparking at the points and to minimise metal transfer either from the fixed contact to the moving one (or vice versa), is not some random value, having to be enough, but not too much.

The later 6CA plate was a much better arrangement in a number of ways, also making the optimisation of the correct value capacitors simple.

However with the 4CA condenser terminal also being the anchoring point for the contact spring, existing 4CA plates were probably just left as they were. The condensers on the 4CA plates were physically quite small to fit in the space available, which possibly limited how much capacity could be crammed into the casing.

Perhaps the extra condensors at the coils were an in-production compromise to suit Triumph's in-service needs .

Regardless, these old condensers typically were made with rolled up layers of aluminium foil, interspersed with a paper dielectric soaked in a thin oil, like paraffin. Apart from the conditions these condensers were exposed to, all paper capacitors of that generation, are well known to dry out and deteriorate with age, even if lying on a shelf unused,

This makes any condenser 50+ years old on a bike suspect.

Terry
 

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Discussion Starter · #23 ·
Hi Furbrain,

Here's another link worth having a look at:

Lucas ET Ignition Unraveled

It looks like those ignition coils you have may be Emgo part number 24-71532 "Universal" coils. They are supposedly "suitable for 6 Volt, 12 Volt and CD systems", but ET systems are not mentioned. Information elsewhere specs them with a 1 Ohm primary DC resistance, which more or less ties up with what you measured.

You got 1.3 Ohms, before taking the reading, did you touch the meter leads together to take the resistance of the meter leads alone, to subtract it from the reading you got?

On a AC system like this, taking a DC resistance reading is of very limited value, what matters is Impedance (AC resistance), unfortunately your meter cannot measure that to compare the coils. However, if it becomes necessary later, there is a fairly basic method to measure it, but we can go into that later if needed.

Both the the link above and the previous one seem to indicate that the Emgo coils will work on an ET system.

Its also interesting that the ET system uses 2 condensers for each cylinder, one at the points and another at the coil in each case. It is also mentioned on the above site, that both are needed for this system to work.

If the condensers you have are original, are they still working, I wonder? Might be worth checking!

A simple test to give you some indication - the condensers will need to be disconnected for this.

Set your DVM to 200k on the resistance scale.

Connect the meter leads to the condenser - what you should see, is an initial low resistance, which increases as it charges up and then settles at a very high value or even above what the meter can read. This should be a quick rise.
If the reading stays low, the condenser is no good.

If it passes this test, change the range to 200 Ohm scale and use the meter to "charge" the condenser for a few seconds.

Remove the leads and switch the meter to the 20 Volt DC voltage range - After a few seconds, by the time you have done this, touch the leads on the condenser and see if it has retained any of the charge. What you should see, is an initial voltage that then reduces as the meter discharges the condenser.

If it passes this test, charge it again on the 200 Ohm resistance setting and try leaving it for a minute or two, before checking the voltage again as before. If it passes this test, it is in good condition.

These simple tests will not indicate the actual capacitance of each condenser, but they will show if they are still working.

Terry
Greetings Terry,
Apologies for the late reply.
The information you send is very, very interesting!.
Can't thank all involved with my bike situation.
I am busy with other stuff at the moment and will be abroad for a few weeks before being able to resume work on the bike.
At least I know now that the Emgo coils should work (without suppressor plug cap).
Will update in the nearish future on progress.
'Never give up........Never surrender'. I am confident that ET will phone home....... sometime.

Take care,......it's a jungle out there!.
 

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Discussion Starter · #24 ·
Hi Furbrain,

Here's another link worth having a look at:

Lucas ET Ignition Unraveled

It looks like those ignition coils you have may be Emgo part number 24-71532 "Universal" coils. They are supposedly "suitable for 6 Volt, 12 Volt and CD systems", but ET systems are not mentioned. Information elsewhere specs them with a 1 Ohm primary DC resistance, which more or less ties up with what you measured.

You got 1.3 Ohms, before taking the reading, did you touch the meter leads together to take the resistance of the meter leads alone, to subtract it from the reading you got?

On a AC system like this, taking a DC resistance reading is of very limited value, what matters is Impedance (AC resistance), unfortunately your meter cannot measure that to compare the coils. However, if it becomes necessary later, there is a fairly basic method to measure it, but we can go into that later if needed.

Both the the link above and the previous one seem to indicate that the Emgo coils will work on an ET system.

Its also interesting that the ET system uses 2 condensers for each cylinder, one at the points and another at the coil in each case. It is also mentioned on the above site, that both are needed for this system to work.

If the condensers you have are original, are they still working, I wonder? Might be worth checking!

A simple test to give you some indication - the condensers will need to be disconnected for this.

Set your DVM to 200k on the resistance scale.

Connect the meter leads to the condenser - what you should see, is an initial low resistance, which increases as it charges up and then settles at a very high value or even above what the meter can read. This should be a quick rise.
If the reading stays low, the condenser is no good.

If it passes this test, change the range to 200 Ohm scale and use the meter to "charge" the condenser for a few seconds.

Remove the leads and switch the meter to the 20 Volt DC voltage range - After a few seconds, by the time you have done this, touch the leads on the condenser and see if it has retained any of the charge. What you should see, is an initial voltage that then reduces as the meter discharges the condenser.

If it passes this test, charge it again on the 200 Ohm resistance setting and try leaving it for a minute or two, before checking the voltage again as before. If it passes this test, it is in good condition.

These simple tests will not indicate the actual capacitance of each condenser, but they will show if they are still working.

Terry
Hi Terry, I've had some fun timing the bike 'old school' like it describes in the link you sent me!.
Clean b7es's gap .5mm and she started first kick,........yeehaa!.
However,.......it wasn't long before it behaved like it was before.........some black smoke and symptoms of running rich. Sure enough the plugs where covered in soot!.
My gut is still saying that it is still lack of power to plugs rather than rich fuel delivery.

I have just removed the primary casing and 'think' there maybe a weak magnet.
To be honest I expected to be able to stick a reasonable size screwdriver on the rotor and use some force to take it off???. Maybe I'm expecting too much!.
Could it be that the magnet is indeed weak?. Strong enough to make the bike start but not strong enough to make the nice strong spark that I've never seen!.
How do I test this magnet and should they be strong enough to hold a hefty piece of steel on them?.
The more I find out about this bike the more determined I am to keep it original if I can!.
Look forward to any thoughts about magnet strength.
Cheers....
Hi,

Wrote my earlier text in a bit of a rush before I went to work. Thinking about it on a 160-mile round trip mostly with cruise control on, I realised "suitable for 6 Volt, 12 Volt and CD systems" was written by an electrical illiterate, it's impossible. Quick internet search doesn't find the a link to an actual Emgo webpage, so dunno whether the sellers are parroting bum information from Emgo or inventing it themselves.

The impossibility has to do with primary resistance. @Furbrain has already measured 1.3~1.4 Ohm, that's high for a CDI coil, marginal for a '6V' (DC) coil but wa-aa-ay to low for a '12V' coil.

The primary criterion for a DC coil switched by points (or points-replacement EI) is the primary draws 3~4 Amps when the rated Volts are applied across it. Ohm's Law (E=IR, Volts = Amps multiplied by Ohms) says a '6V' coil must have primary resistance between 2 Ohms and 1.5 Ohms respectively, a '12V' coil must have primary resistance between 4 Ohms and 3 Ohms respectively ... i.e. take a '6V' coil and apply 12V across its primary, it'll draw between 6 and 8 Amps ... it'll get very hot just before it burns out ... :oops:

Otoh, CDI coils are charged with a very short (milliseconds) burst of relatively-high Volts (400V?); because the charge duration is very short, primary resistance would be a hindrance, they don't heat up because the charge duration is so short.

In addition, in Repairing an ET Ignition System, "Magnetoman" states CDI coils have a much lower secondary resistance - ~2.5 KOhms, vs. the 5~6 Kohms of an ET coil, that's been measured and posted earlier in the thread.


Uh-uh, ET doesn't "need" four condensers to work; certainly in '66 and '67, both AC and DC systems show four condensers.

Lucas put the condensers on the 4CA points plate; as "Magnetoman" explained, that is indeed desirable for the primary reason of protecting the points when opening and closing, irrespective of whether the electrics are AC or DC. As I posted above, snag with that arrangement is Lucas failed to protect the condensers from engine heat; :oops: 4CA points-plate condensers have always been notorious for their short lives.

Fifty-plus years on, it's hard to know the real reason for four condensers (two on the points plate and two external), possibly simply to save scrapping a large number of 4CA points plates when the balls-up became apparent? Once the 4CA was superseded by the 6CA, there are only the two external condensers; as "Magnetoman" explains, not such good protection for the points but, given the external condensers' increased longevity, that the points were protected for longer was considered an acceptable compromise?

Hth.

Regards,
Hi Stuart,
At last I've found the root of my spark problem!
Turns out the rotor has made itself a nice groove and 3 of the stator coil pickups are well worn. I can't believe the bike ran at all,.........
Anyway, will delve further.
I have a horrible feeling that the main left bearing might be worn. Would it be physically possible to move the shaft up and down(wiggle it) if the bearing was worn?.
I must admit, the stator mounting studs weren't that tight (one unscrewed from the crankcase completely ) and nuts felt like they were 'nipped' up only. Mmmmmm........not sure if that would be cause of the pickups only wearing one side and wearing the rotor.
Of course I'm hoping that's the case,......... however I suspect the dreaded engine strip for a new main bearing.
At least I'm learning about the bike . I will persevere.......
Take care,
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Hi.
maybe a weak magnet.
expected to be able to stick a reasonable size screwdriver on the rotor and use some force to take it off?
Could it be that the magnet is indeed weak?
The rotor has six magnets.

The rule-of-thumb tests were either to stick it to the underside of the exhaust and roll it along, or stick a spanner on it and lift it with the spanner. If it won't pass either test, bear in mind magnetic strength attenuates with age, the rotor is 55? years old (it's stamped with a date code of one- or two-figure week number plus two-figure year number?) and the rotor rubbing on the stator won't have done either any good. (n)

stator mounting studs weren't that tight (one unscrewed from the crankcase completely ) and nuts felt like they were 'nipped' up only.
not sure if that would be cause of the pickups only wearing one side
:rolleyes: The perils of an old engine "rebuilt" by an unknown ...

Stator securing nuts should only be tightened to 8 lb.ft. (not the 20 in the workshop manual :eek:); otoh, a stator mounting stud should not simply unscrew from the crankcase ... Studs are easy for the home bodger to fit or unscrew ... trouble is, mole grips always leave witness marks ... :rolleyes: Proper stud extracting/fitting tools are expensive, and afaik no-one makes 'em for British Standard threads ... Otoh, many decades ago, the engineer I was using at the time for one-off bits made me a 'set' - in reality, a collection of ~1" lengths of hex. bar drilled and tapped for the common threads on a T160; if you have a local engineer or machinist, say and I'll post more details.

Stator ID should have between 8 thou. and 12 thou. (0.008"-0.012") clearance all round a rotor ID; stator ID "only wearing one side" could be your bike's engine rebuilder" was simply careless checking. :(

Otoh, if you can detect any up-down or side-to-side movement at the end of the crank, something's knackered (hopefully just the main bearing); however, even if you can't detect any of the aforementioned movement, doesn't mean the bearing isn't knackered - the energy in the pistons, rods and crank big-ends at even a thousand rpm is considerably more than you can exert on the end of the crank,

engine strip for a new main bearing.
Wise anyway, your bike's crank oil feed is through the timing-side bush that's also the bearing there. Not as infamously troublesome as the similar arrangement on BSA twins, but no sense buggering possibly perfectly-good big-end bearings because the previous "rebuilder" couldn't be arsed to do the timing-side bush properly? Be aware, if the bush does need doing, because it's also the timing-side main bearing, "properly" means someone specifically capable of finish-reaming the new bush concentric with the drive-side main bearing.

I will persevere.
(y)

Hth.

Regards,
 

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Discussion Starter · #26 ·
Hi.

The rotor has six magnets.

The rule-of-thumb tests were either to stick it to the underside of the exhaust and roll it along, or stick a spanner on it and lift it with the spanner. If it won't pass either test, bear in mind magnetic strength attenuates with age, the rotor is 55? years old (it's stamped with a date code of one- or two-figure week number plus two-figure year number?) and the rotor rubbing on the stator won't have done either any good. (n)


:rolleyes: The perils of an old engine "rebuilt" by an unknown ...

Stator securing nuts should only be tightened to 8 lb.ft. (not the 20 in the workshop manual :eek:); otoh, a stator mounting stud should not simply unscrew from the crankcase ... Studs are easy for the home bodger to fit or unscrew ... trouble is, mole grips always leave witness marks ... :rolleyes: Proper stud extracting/fitting tools are expensive, and afaik no-one makes 'em for British Standard threads ... Otoh, many decades ago, the engineer I was using at the time for one-off bits made me a 'set' - in reality, a collection of ~1" lengths of hex. bar drilled and tapped for the common threads on a T160; if you have a local engineer or machinist, say and I'll post more details.

Stator ID should have between 8 thou. and 12 thou. (0.008"-0.012") clearance all round a rotor ID; stator ID "only wearing one side" could be your bike's engine rebuilder" was simply careless checking. :(

Otoh, if you can detect any up-down or side-to-side movement at the end of the crank, something's knackered (hopefully just the main bearing); however, even if you can't detect any of the aforementioned movement, doesn't mean the bearing isn't knackered - the energy in the pistons, rods and crank big-ends at even a thousand rpm is considerably more than you can exert on the end of the crank,


Wise anyway, your bike's crank oil feed is through the timing-side bush that's also the bearing there. Not as infamously troublesome as the similar arrangement on BSA twins, but no sense buggering possibly perfectly-good big-end bearings because the previous "rebuilder" couldn't be arsed to do the timing-side bush properly? Be aware, if the bush does need doing, because it's also the timing-side main bearing, "properly" means someone specifically capable of finish-reaming the new bush concentric with the drive-side main bearing.


(y)

Hth.

Regards,
Hi Stuart.
Once again the information is greatly appreciated. Before going further, do I reply using small icon on left OR use text box at bottom. As you have probably guessed I'm not used to forums and not sure where I should reply and post. I will formally introduce myself very soon. Obviously you and Terry have helped very much.

Ok,........on with the saga......
The magnet on rotor is strong and passed your test. However, as seen with photo it's not something I can use again. The stator puzzles me a bit. I send 2 photos. One shows 3 pickups that are knackered and obviously the ones that have reshaped the rotor. The other 3 pickups are perfect!.
My logic(questionable sometimes) is telling me that if the main bearing was worn then all 6 pickups would be at least be marked?. Surely the crankshaft would wobble and affect the whole stator and not just one side?.
I'm still wondering about the studs and their looseness.
As you know, you can tighten something up on a stud and it can feel sturdy ish........ however for proper effect the stud must be secure on its own!.
Would it be possible for the stator to move enough and cause contact with the rotor?.
Great idea about using hex for making stud fasteners. Hope you don't think I'm a bodger but I've always used 2 nuts, locked them, tighten stud and then remove the two nuts.
If this is a bad idea then please say. It's pretty obvious that you and Terry know your stuff.
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Hi,
reply using small icon on left OR use text box at bottom.
Either, If you click on "Reply" at the bottom of a post, the Forum software copies that post's text into the box at the bottom - can be useful if you want to reply to parts of a previous post. Otoh, if you don't want that, simply just type in the box at the bottom.

A useful little wrinkle - if, say, you needed to refer to photos. in the post you're replying to - is to hover the cursor over "Reply", click the right mouse button and then click on "Open link in a new tab" ("Reply" is a "link"); that copies the post text (and any photos.) to a bigger text box in another browser tab.

stator
3 pickups that are knackered
other 3 pickups are perfect!
These are the ends of the stator coils' cores. The basic principle the alternator works on is a rotor magnet passing a stator coil, the magnetism induces electron movement in the coil's wire. The rotor's six magnets are arranged with north and south poles alternating; as a given magnet passes a given coil, the magnet induces electron movement in one direction in the coil; the next magnet passing the same coil induces electron movement in the other direction ... hence Alternating Current. :)

My logic(questionable sometimes) is telling me that if the main bearing was worn then all 6 pickups would be at least be marked?. Surely the crankshaft would wobble and affect the whole stator and not just one side?
Might depend where the three knackered stator coil ends were located? Rotor clearance within the stator should be checked three or four times, with the rotor rotated to different positions relative to the stator. Say, for the sake of argument, the main bearing was worn up-down; if rotor clearance was set with the crank 'down', when the engine's running and the pistons reach the top of the stroke, they'll exert enough force to pull the crank, and rotor, 'up'?

Another problem to be aware of is the bearing can spin in the case, then the bearing's steel outer race wears the case ally, possibly oval; if the rebuilder didn't both having the bearing housing bored round again (and the new clearance taken up with either an oversize bearing or a standard bearing shimmed), the bearing could be moving in the case. :(

One way of finding whether the "rebuilder" was simply careless setting the rotor-stator clearance, or what you really have is a Triumph boat-anchor, would be to reassemble stator on studs, rotor on crank and see if there's 8~12 thou. all round?

hex for making stud fasteners.
I've always used 2 nuts, locked them, tighten stud and then remove the two nuts.
(y) if there's enough threaded length for two nuts.

Otoh, length of hex. bar drilled 'n' tapped for the thread and screwed on to the stud thread, because the bar is secured on the stud with a bolt in the other end of the bar, doesn't matter if the stud only has a short threaded length. Also, if the bar hex. is chosen with some thought, two different spanners can be used - e.g. 1/4"UNF is normally 7/16" AF; my 1/4"UNF stud extractor/fitter hex. bar is a piece of 1/2" AF; the securing bolt is held/turned with a 7/16" AF spanner, the hex. bar is held/turned with a 1/2" AF spanner. (y)

Hth.

Regards,
 

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Discussion Starter · #28 ·
Hi,

Either, If you click on "Reply" at the bottom of a post, the Forum software copies that post's text into the box at the bottom - can be useful if you want to reply to parts of a previous post. Otoh, if you don't want that, simply just type in the box at the bottom.

A useful little wrinkle - if, say, you needed to refer to photos. in the post you're replying to - is to hover the cursor over "Reply", click the right mouse button and then click on "Open link in a new tab" ("Reply" is a "link"); that copies the post text (and any photos.) to a bigger text box in another browser tab.


These are the ends of the stator coils' cores. The basic principle the alternator works on is a rotor magnet passing a stator coil, the magnetism induces electron movement in the coil's wire. The rotor's six magnets are arranged with north and south poles alternating; as a given magnet passes a given coil, the magnet induces electron movement in one direction in the coil; the next magnet passing the same coil induces electron movement in the other direction ... hence Alternating Current. :)


Might depend where the three knackered stator coil ends were located? Rotor clearance within the stator should be checked three or four times, with the rotor rotated to different positions relative to the stator. Say, for the sake of argument, the main bearing was worn up-down; if rotor clearance was set with the crank 'down', when the engine's running and the pistons reach the top of the stroke, they'll exert enough force to pull the crank, and rotor, 'up'?

Another problem to be aware of is the bearing can spin in the case, then the bearing's steel outer race wears the case ally, possibly oval; if the rebuilder didn't both having the bearing housing bored round again (and the new clearance taken up with either an oversize bearing or a standard bearing shimmed), the bearing could be moving in the case. :(

One way of finding whether the "rebuilder" was simply careless setting the rotor-stator clearance, or what you really have is a Triumph boat-anchor, would be to reassemble stator on studs, rotor on crank and see if there's 8~12 thou. all round?


(y) if there's enough threaded length for two nuts.

Otoh, length of hex. bar drilled 'n' tapped for the thread and screwed on to the stud thread, because the bar is secured on the stud with a bolt in the other end of the bar, doesn't matter if the stud only has a short threaded length. Also, if the bar hex. is chosen with some thought, two different spanners can be used - e.g. 1/4"UNF is normally 7/16" AF; my 1/4"UNF stud extractor/fitter hex. bar is a piece of 1/2" AF; the securing bolt is held/turned with a 7/16" AF spanner, the hex. bar is held/turned with a 1/2" AF spanner. (y)

Hth.

Regards,
Hi Stuart, thank you for your time and expertise.
I understand all that you are saying.
It's a shame that I didn't do lots of clearance tests to stator/rotor BEFORE removing the stator. Oh well..... hindsight eh!. I will set it up again after I fit the studs properly and check clearance all round. However I'm not sure that will prove anything as the gap at the worn pickups will be greater anyhow......in theory.
I will let you know soonish....

You mentioned 'setting' the stator. I'm not sure how this can be done as the studs are in a fixed position?. Unless the studs are bent ( they look ok) then there is only one position the stator can go?.

Busy with other boring stuff today but will update asap.
Thanks for your patience.

I wonder if Terry is following this thread?. It seems he has worked on these bikes a lot in the past and wonder if he has ever seen a rotor worn like this?.
Onwards and hopefully upwards.
 

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setting the rotor-stator clearance
not sure how this can be done as the studs are in a fixed position?
Unfortunately neither the original Lucas company nor current pattern stator makers always have stator centre and mounting holes in exactly the same relationship. :( However, thankfully, because the clearance is small in total, any change is smaller and, because it's at one end of the studs, it's smaller still at their other ends.

I like to:-

. first separately ascertain rotor fits on crank and stator mounting holes fit over mounting studs, rotor OD is concentric with centre;

. then measure rotor OD and stator ID and make up a non-magnetic spacer or shims to centre the rotor in the stator off the bike - some plastic soft-drinks bottles are the right ID, OD and wall thickness to make a rotor-stator spacer, or shims can be made from bits from ally drinks cans.

Rotor and stator assembled as a unit off the bike, attempting to slide the rotor on to the crank will show which, if any, studs are 'off', they can be 'fettled' in the appropriate direction but, as I say, the movement where the stator fits is tiny, so the pressure where they fit in the crankcase is even tinier.

I will warn the above method is extremely time-consuming, you have to be in the right frame of mind, and the patience of Job is still required. :( However, the reward is a rotor and stator in the correct relationship, (y) not "that'll do".

One tip I'll add is if, when you start, all the studs are 'off' by the same amount, quicker is to remove the rotor and spacer/shims from the stator, slip the stator over all three studs and move them the same amount. Regrettably, this can't be done with the rotor fitted as that limits the stator's and studs' movement, the studs'll just spring the stator back to its original position. :mad:

Once the rotor-stator 'unit' slides on to all four (crank and three studs) at the same time, tighten rotor and stator nuts and pull out the spacer/shims - you should :whistle: be rewarded with the same clearance all round ... also when the rotor is rotated to different positions.

Hth.

Regards,
 

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Discussion Starter · #30 ·
Hi

Unfortunately neither the original Lucas company nor current pattern stator makers always have stator centre and mounting holes in exactly the same relationship. :( However, thankfully, because the clearance is small in total, any change is smaller and, because it's at one end of the studs, it's smaller still at their other ends.

I like to:-

. first separately ascertain rotor fits on crank and stator mounting holes fit over mounting studs, rotor OD is concentric with centre;

. then measure rotor OD and stator ID and make up a non-magnetic spacer or shims to centre the rotor in the stator off the bike - some plastic soft-drinks bottles are the right ID, OD and wall thickness to make a rotor-stator spacer, or shims can be made from bits from ally drinks cans.

Rotor and stator assembled as a unit off the bike, attempting to slide the rotor on to the crank will show which, if any, studs are 'off', they can be 'fettled' in the appropriate direction but, as I say, the movement where the stator fits is tiny, so the pressure where they fit in the crankcase is even tinier.

I will warn the above method is extremely time-consuming, you have to be in the right frame of mind, and the patience of Job is still required. :( However, the reward is a rotor and stator in the correct relationship, (y) not "that'll do".

One tip I'll add is if, when you start, all the studs are 'off' by the same amount, quicker is to remove the rotor and spacer/shims from the stator, slip the stator over all three studs and move them the same amount. Regrettably, this can't be done with the rotor fitted as that limits the stator's and studs' movement, the studs'll just spring the stator back to its original position. :mad:

Once the rotor-stator 'unit' slides on to all four (crank and three studs) at the same time, tighten rotor and stator nuts and pull out the spacer/shims - you should :whistle: be rewarded with the same clearance all round ... also when the rotor is rotated to different positions.

Hth.

Regards,
Many thanks. I understand what you say and will give it my best shot asap.
Yes Stuart, patience is something needed when trying to revive a bit of history!.
Never give up and never surrender!.
My facination is in the way bikes where built 'back in the day'. Pretty crude and agricultural but never forgetting that these machines were the forerunners to some pretty impressive Japanese engineering.
Thanks again for your time.............👍.
Will update when I've tried what you suggest.
 

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Discussion Starter · #31 ·
Hi

Unfortunately neither the original Lucas company nor current pattern stator makers always have stator centre and mounting holes in exactly the same relationship. :( However, thankfully, because the clearance is small in total, any change is smaller and, because it's at one end of the studs, it's smaller still at their other ends.

I like to:-

. first separately ascertain rotor fits on crank and stator mounting holes fit over mounting studs, rotor OD is concentric with centre;

. then measure rotor OD and stator ID and make up a non-magnetic spacer or shims to centre the rotor in the stator off the bike - some plastic soft-drinks bottles are the right ID, OD and wall thickness to make a rotor-stator spacer, or shims can be made from bits from ally drinks cans.

Rotor and stator assembled as a unit off the bike, attempting to slide the rotor on to the crank will show which, if any, studs are 'off', they can be 'fettled' in the appropriate direction but, as I say, the movement where the stator fits is tiny, so the pressure where they fit in the crankcase is even tinier.

I will warn the above method is extremely time-consuming, you have to be in the right frame of mind, and the patience of Job is still required. :( However, the reward is a rotor and stator in the correct relationship, (y) not "that'll do".

One tip I'll add is if, when you start, all the studs are 'off' by the same amount, quicker is to remove the rotor and spacer/shims from the stator, slip the stator over all three studs and move them the same amount. Regrettably, this can't be done with the rotor fitted as that limits the stator's and studs' movement, the studs'll just spring the stator back to its original position. :mad:

Once the rotor-stator 'unit' slides on to all four (crank and three studs) at the same time, tighten rotor and stator nuts and pull out the spacer/shims - you should :whistle: be rewarded with the same clearance all round ... also when the rotor is rotated to different positions.

Hth.

Regards,
As a postscript, my stator studs have separate cotton reel spacers. I see there are studs available with cotton reels machined in to them. Not sure, but I wonder if they would be more solid than my setup?.
 

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Discussion Starter · #32 ·
Hi

Unfortunately neither the original Lucas company nor current pattern stator makers always have stator centre and mounting holes in exactly the same relationship. :( However, thankfully, because the clearance is small in total, any change is smaller and, because it's at one end of the studs, it's smaller still at their other ends.

I like to:-

. first separately ascertain rotor fits on crank and stator mounting holes fit over mounting studs, rotor OD is concentric with centre;

. then measure rotor OD and stator ID and make up a non-magnetic spacer or shims to centre the rotor in the stator off the bike - some plastic soft-drinks bottles are the right ID, OD and wall thickness to make a rotor-stator spacer, or shims can be made from bits from ally drinks cans.

Rotor and stator assembled as a unit off the bike, attempting to slide the rotor on to the crank will show which, if any, studs are 'off', they can be 'fettled' in the appropriate direction but, as I say, the movement where the stator fits is tiny, so the pressure where they fit in the crankcase is even tinier.

I will warn the above method is extremely time-consuming, you have to be in the right frame of mind, and the patience of Job is still required. :( However, the reward is a rotor and stator in the correct relationship, (y) not "that'll do".

One tip I'll add is if, when you start, all the studs are 'off' by the same amount, quicker is to remove the rotor and spacer/shims from the stator, slip the stator over all three studs and move them the same amount. Regrettably, this can't be done with the rotor fitted as that limits the stator's and studs' movement, the studs'll just spring the stator back to its original position. :mad:

Once the rotor-stator 'unit' slides on to all four (crank and three studs) at the same time, tighten rotor and stator nuts and pull out the spacer/shims - you should :whistle: be rewarded with the same clearance all round ... also when the rotor is rotated to different positions.

Hth.

Regards,
Something else,.........
I notice some metal at the base of the rotor locating pin ( see photo).
Not sure how much this would affect things. Probably only about .25mm thick but will not help in the final seating of rotor. ie, it will be very very slightly tilted. Ho hum the beat goes on!.
I have set the rotor/Stator with shims as per suggestion and offered both to the now well fixed studs and crankshaft.
It looks quite good,..... but bear in mind three pickups are worn and the stator is grooved and cupped. This would be more accurate if stator and rotor were in good condition.
I have no option but to buy new setup. These items are knackered.
Update again soon.
 

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Discussion Starter · #33 ·
Hi

Unfortunately neither the original Lucas company nor current pattern stator makers always have stator centre and mounting holes in exactly the same relationship. :( However, thankfully, because the clearance is small in total, any change is smaller and, because it's at one end of the studs, it's smaller still at their other ends.

I like to:-

. first separately ascertain rotor fits on crank and stator mounting holes fit over mounting studs, rotor OD is concentric with centre;

. then measure rotor OD and stator ID and make up a non-magnetic spacer or shims to centre the rotor in the stator off the bike - some plastic soft-drinks bottles are the right ID, OD and wall thickness to make a rotor-stator spacer, or shims can be made from bits from ally drinks cans.

Rotor and stator assembled as a unit off the bike, attempting to slide the rotor on to the crank will show which, if any, studs are 'off', they can be 'fettled' in the appropriate direction but, as I say, the movement where the stator fits is tiny, so the pressure where they fit in the crankcase is even tinier.

I will warn the above method is extremely time-consuming, you have to be in the right frame of mind, and the patience of Job is still required. :( However, the reward is a rotor and stator in the correct relationship, (y) not "that'll do".

One tip I'll add is if, when you start, all the studs are 'off' by the same amount, quicker is to remove the rotor and spacer/shims from the stator, slip the stator over all three studs and move them the same amount. Regrettably, this can't be done with the rotor fitted as that limits the stator's and studs' movement, the studs'll just spring the stator back to its original position. :mad:

Once the rotor-stator 'unit' slides on to all four (crank and three studs) at the same time, tighten rotor and stator nuts and pull out the spacer/shims - you should :whistle: be rewarded with the same clearance all round ... also when the rotor is rotated to different positions.

Hth.

Regards,
Still more!.
I measure crank to studs overall measurement (see quality drawing).
Cheap Vernier and I'm not an engineer however it's obvious that the studs are not central to crank!. I've obviously taken studs out and refitted so it's possible that if studs were bent slightly before this would make the difference.
 

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You should be able to see a stud end "walking" as you screw it in if it's bent. Unfortunately, the are usually bent near the bottom, so rolling on a flat surface doesn't show it up.
 

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Hi,
my stator studs have separate cotton reel spacers. I see there are studs available with cotton reels machined in to them
wonder if they would be more solid than my setup?
Two potential difficulties:-

. Your bike's studs likely have British Standard threads (BSF into the crankcase, Cycle for the nuts), the later studs likely have UNC into the crankcase and UNF for the nuts.

. If necessary, you can adjust the length of your bike's spacers to have the axial centre of the stator over the axial centre of the rotor. No adjustment in the later type if they aren't accurate ... (n)

notice some metal at the base of the rotor locating pin ( see photo).
:confused: Don't see this particular photo.?

You should be able to see a stud end "walking" as you screw it in if it's bent. Unfortunately, the are usually bent near the bottom, so rolling on a flat surface doesn't show it up.
The studs might not be bent; could be the angle of the thread in the crankcase.

Unscrew each stud half-a-turn and take your measurements again; the end of a bent stud will be a different distance from the crank centre.

Try rolling them on a really flat surface (piece of plate glass?) anyway, either a bent end, or the middle oscillating as it rolls, might show up.

Hth.

Regards,
 

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Discussion Starter · #36 ·
You should be able to see a stud end "walking" as you screw it in if it's bent. Unfortunately, the are usually bent near the bottom, so rolling on a flat surface doesn't show it up.
Thanks Mick,
Your input makes perfect sense. Will update asap.
Hi,

Two potential difficulties:-

. Your bike's studs likely have British Standard threads (BSF into the crankcase, Cycle for the nuts), the later studs likely have UNC into the crankcase and UNF for the nuts.

. If necessary, you can adjust the length of your bike's spacers to have the axial centre of the stator over the axial centre of the rotor. No adjustment in the later type if they aren't accurate ... (n)


:confused: Don't see this particular photo.?


The studs might not be bent; could be the angle of the thread in the crankcase.

Unscrew each stud half-a-turn and take your measurements again; the end of a bent stud will be a different distance from the crank centre.

Try rolling them on a really flat surface (piece of plate glass?) anyway, either a bent end, or the middle oscillating as it rolls, might show up.

Hth.

Regards,
Have hopefully attached photo this time!.
I've taken engine sprocket off and measured between crankshaft and stator studs at the base of the studs and find all is central!. Studs must therefore be bent. I understand about having to 'fettel' the studs and setting up the rotor within the stator BEFORE final fitting which is a brilliant idea. However, I will only be able to do this with a new Stator and rotor as the originals are so badly worn!.
That piece of metal at the base of the rotor pin (shown in photo) is yet another mystery?.
Will carefully remove it!.
More updates at some point.
I'm still unsure as to the reason the rotor/stator ended up this way. Was bad/ careless fitting the cause or problem with main bearing?.
Another thing,..,....making shorter spacers for stator studs is interesting. See original rotor photos and notice that the axial centre is no where near!. Automotive tire Bicycle part Motor vehicle Rim Gear
 

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Thanks Mick,
Your input makes perfect sense. Will update asap.

Have hopefully attached photo this time!.
I've taken engine sprocket off and measured between crankshaft and stator studs at the base of the studs and find all is central!. Studs must therefore be bent. I understand about having to 'fettel' the studs and setting up the rotor within the stator BEFORE final fitting which is a brilliant idea. However, I will only be able to do this with a new Stator and rotor as the originals are so badly worn!.
That piece of metal at the base of the rotor pin (shown in photo) is yet another mystery?.
Will carefully remove it!.
More updates at some point.
I'm still unsure as to the reason the rotor/stator ended up this way. Was bad/ careless fitting the cause or problem with main bearing?.
Another thing,..,....making shorter spacers for stator studs is interesting. See original rotor photos and notice that the axial centre is no where near!. View attachment 765299
That stuff around the "rotor pin" looks like the hole in the sprocket has got oversize, and a sort of shim has been made and the pin pressed into it. Not great, but if the rotor goes on ok and the nut is good and tight, then it shouldn't cause a problem of itself. You would need to trim off those excess bits, otherwise they will cant the rotor, maybe that's already happened? I think if I was going to change the rotor etc, I'd change the sprocket and pin too - it's just possible that the pin is not the correct diameter, I'd check against the holes in the rotor.
HTH
 

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Discussion Starter · #38 ·
That stuff around the "rotor pin" looks like the hole in the sprocket has got oversize, and a sort of shim has been made and the pin pressed into it. Not great, but if the rotor goes on ok and the nut is good and tight, then it shouldn't cause a problem of itself. You would need to trim off those excess bits, otherwise they will cant the rotor, maybe that's already happened? I think if I was going to change the rotor etc, I'd change the sprocket and pin too - it's just possible that the pin is not the correct diameter, I'd check against the holes in the rotor.
HTH
Hi Mick,
I thought the same,.....homemade shim. Can't understand why as the pin makes nice fit as is ???.
To add to this conundrum I notice some, not many, tiny pieces of metal embedded into some, not all, bonded clutch plates. At some stage loose metal has been having a party in that area and I'm now wondering if that homemade pin shim would be the main culprit for reeking havoc and possibly messing up the stator pickups before heading over to clutch department. Mmmmmm..........a conundrum indeed!.

Just for curiosity, how far away from the rotor can a pickup be in order for the system to still produce adequate electricity.
Obviously closer the better (.2mm) recommended.
Please see earlier photo of sculpted rotor.
IF I can centralise stator which I think I can, then shorten the stator stud spacers by +/-8mm which would make Stator sit above the good bit left on the rotor, would I be daft to try using my stator/rotor again?. Maybe both items are just too far gone,..............but comments welcome please. Wood Font Tints and shades Circle Concrete
 

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Hi,
how far away from the rotor can a pickup be in order for the system to still produce adequate electricity.
Lucas said 12 thou max. Magnetic force attenuates very rapidly with distance - e.g. a fridge magnet will hold, say, one piece of paper; it'll fall off if you try to get it to hold, say, three pieces of paper ... :(

Also, unlike AC being rectified to DC which generates the HT spark, ET ignition depends directly on the energy in the stator coils

daft to try using my stator/rotor again?
Imho, yes.

Firstly, do you know the functions of the three coils that've been damaged? Bear in mind each is in series with another - one end of each coil will be connected to another, so you probably need to trace the connections of at least two and possibly all three to find out which external wire each one is connected to.

Also, absent a manufacturing date on the rotor, it isn't safe to assume it isn't one where the magnets simply sit on the faces of the central hex., held in place by the non-magnetic material cast around them. It's well-known for rotors that haven't suffered the damage your bike has to start loosening off, clearance develops between hex. and magnets, engine accelerated and decelerated, the hex. starts to push the magnets outwards ... the magnets can only go the few thou. clearance to the stator before they hit it ...

Hth.

Regards,
 
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