[mph dawson]

Hi all I have a 1972 Triumph Bonneville t120v 25500 genuine miles. The engine was rebuilt 20 years ago by a PO. It is all receipted the bike has done 3500 miles in the 20 years since and I have done 400 of them. I have owned the bike for 8 months and I rebuilt the chassis and rewired and upgraded the electrics.as both were in a state. I have the primary cover off to change the gearbox sprocket and the clutch plates.
I know from the receipts that the duplex chain was replaced but not the sprockets. . Once complete I hope to do circa 3-4000 miles per annum.
1. How many more miles can I expect from the existing duplex sprockets - They look ok and are showing minimal wear
2. If the consensus is to replace them then can anyone recommend a good manufacturer and supplier of the hard anodised clutch or should I stick with steel. Websites don't seem to mention who makes them it simply says uk supplier. Maybe just new rubbers will suffice . The clutch does slip but as I have said I am intending to upgrade to a 7 plate system.
3. I fitted a Mofset regulator which will operate 3 phase so maybe I ought to also look at upgrading the stator and rotor because both are original and nearly 50 years old . From what I can see a RM24 stator and rotor could do the job. So again same question do the original parts fail and at what point. Would it be therefore prudent to change the originals and if so then with what manufacturers part and where from.
I ask because I have had mixed results when replacing parts , though to be fair it has been mostly positive . There have been a couple of horror stories . As part of the rewire i got a Lucas loom that melted and other parts that I sent back because they were of poor quality. I think the problem with the loom was poor crimping and too thin a gauge cable because when I stripped it from the bike the connectors easily dropped off and the replacement Lucas loom from another supplier is of noticeably better quality, thicker gauge cables and you can unplug a connector without it falling off. All the electrics are now working as is the existing charging system . I also fitted LED lighting so maybe it doesn't require to be 3 phase? . I am asking the question as I am simply thinking whilst it is stripped then maybe I could save future effort by tackling all these jobs all at once. I do not want to spend money for the sake of it especially if I replace something with something that may be new but not as reliable. I am interested to hear peoples experiences opinions,and advice before deciding upon the best course of action

 

[StuartMac]

Hi,

1972 Triumph Bonneville t120v
fitted a Mofset regulator which will operate 3 phase so maybe I ought to also look at upgrading the stator and rotor
do the original parts fail and at what point

Not an easy question to answer because well-spec'd and -fitted electrics left alone go on 'til they fail - generally, "the longer electrics go on, the longer electrics go on."

However, there are two common failure points:-

. Particular to twins is the primary chain damaging the stator cable inside the chaincase.

. Rotor magnetism attenuates with age, but not at a set rate; e.g. if your bike's rotor was left out of the stator for any length of time during the engine rebuild, the rotor magnetism will have attenuated more than if the rotor had always been kept inside the stator.

fitted LED lighting so maybe it doesn't require to be 3 phase?

Depends what you want to do with the bike:-

. If the LED headlamp bulb was simply a replacement for the existing BPF (British Pre Focus) incandescent bulb, the bike still has the crap lens/reflector - fine for other road users seeing you, useless for seeing down the road at night unless you're happy to travel at no more than about 40 mph.

. Otoh, if you also replaced the headlamp lens/reflector with a modern one (P43t bulb base) and its characteristics match the LED bulb, so you're seeing plenty of light projected down the road at night and you'd be happy riding at a similar speed to in daylight?

RM24 stator
replacement Lucas loom from another supplier is of noticeably better quality, thicker gauge cables

Mmmm ... afaik, no-one makes an off-the-shelf loom for any '71-on Britbike with thicker than 14-strand cables so any cable is rated for only 8.75 Amps. Given even the 'low output' version of a 3-phase is rated for 10.5A @ 5,000 rpm and both 3-phase (should) produce 85% of rated @ 2,400 rpm, that's about where the rating of the main Brown/Blue wire is exceeded even with a low-output 3-phase ...

There's an old 'Irish' joke, the punchline of which has a local directing a tourist, "If I was going 'dere, I wouldn't start from here." Similarly, anyone considering upgrading old Britbike electrics, never start with the loom, at least not unless you want to change a lot of it when you want it to connect better bits together.

14-strand loom cables, the only way I'd utilise the 'high output' version of the 3-phase for brighter and more-useful lights than standard is to supply the more-powerful headlamp separately through relays, the handlebar dipswitch switching the relays, not the power for the headlamp directly. Easy to do, no changes to a standard loom.

peoples experiences

Both my T160's have had high-output 3-phase alternators since the early 1980's. Primary aim was (a) more-powerful headlamp(s) - single 60/55 quartz-halogen wasn't enough, single 100/55 turned out to be enough but I'd have fitted twin 60/55 if necessary. Another unexpected gain was electric-start that worked irrespective how long the bike had been plodding along at low engine rpm. But I wired them myself from wire, terminals, insulation, etc., never even contemplated using an off-the-shelf loom. Since then, one bad experience with an off-the-shelf loom, I'd never consider using another, I've always built from components.

Hth.

Regards,

 

[mph dawson]

Hi,

Not an easy question to answer because well-spec'd and -fitted electrics left alone go on 'til they fail - generally, "the longer electrics go on, the longer electrics go on."

However, there are two common failure points:-

. Particular to twins is the primary chain damaging the stator cable inside the chaincase.

. Rotor magnetism attenuates with age, but not at a set rate; e.g. if your bike's rotor was left out of the stator for any length of time during the engine rebuild, the rotor magnetism will have attenuated more than if the rotor had always been kept inside the stator.


Depends what you want to do with the bike:-

. If the LED headlamp bulb was simply a replacement for the existing BPF (British Pre Focus) incandescent bulb, the bike still has the crap lens/reflector - fine for other road users seeing you, useless for seeing down the road at night unless you're happy to travel at no more than about 40 mph.

. Otoh, if you also replaced the headlamp lens/reflector with a modern one (P43t bulb base) and its characteristics match the LED bulb, so you're seeing plenty of light projected down the road at night and you'd be happy riding at a similar speed to in daylight?


Mmmm ... afaik, no-one makes an off-the-shelf loom for any '71-on Britbike with thicker than 14-strand cables so any cable is rated for only 8.75 Amps. Given even the 'low output' version of a 3-phase is rated for 10.5A @ 5,000 rpm and both 3-phase (should) produce 85% of rated @ 2,400 rpm, that's about where the rating of the main Brown/Blue wire is exceeded even with a low-output 3-phase ...

There's an old 'Irish' joke, the punchline of which has a local directing a tourist, "If I was going 'dere, I wouldn't start from here." Similarly, anyone considering upgrading old Britbike electrics, never start with the loom, at least not unless you want to change a lot of it when you want it to connect better bits together.

14-strand loom cables, the only way I'd utilise the 'high output' version of the 3-phase for brighter and more-useful lights than standard is to supply the more-powerful headlamp separately through relays, the handlebar dipswitch switching the relays, not the power for the headlamp directly. Easy to do, no changes to a standard loom.


Both my T160's have had high-output 3-phase alternators since the early 1980's. Primary aim was (a) more-powerful headlamp(s) - single 60/55 quartz-halogen wasn't enough, single 100/55 turned out to be enough but I'd have fitted twin 60/55 if necessary. Another unexpected gain was electric-start that worked irrespective how long the bike had been plodding along at low engine rpm. But I wired them myself from wire, terminals, insulation, etc., never even contemplated using an off-the-shelf loom. Since then, one bad experience with an off-the-shelf loom, I'd never consider using another, I've always built from components.

Hth.

Regards,

Thanks Stuart, If only I have talked to you at the beginning of the project.!!
To be honest I doubt I will be doing much night time riding because my eyes have already reached a point where they are not great at night. I seem to have more of a problem when there is oncoming traffic, rather than actually seeing in the dark if you get my drift..Either way I know I am beginning to struggle so I avoid it where I can . Another of those sneaky ageing tricks that life seems to keep playing on me!
So in essence you think I am better to stick with the existing rotor and stator or at least their outputs if I replace them .
Do you have any thoughts re the life expectancy of the primary drive sprockets because as I have said I have to remove the clutch etc.to replace the gearbox sprocket so I am thinking it may be best to learn to try some preventative maintenance rather than my more usual more reactive approach.
I have a 7 plate conversion and a set of rubbers on order to try and address the slipping but i am not sure how long the centres and baskets last. Certainly on the more modern bikes i have been running and maintaining then I would expect to get circa 10-15k out of a set of friction plates. . To be fair and maybe I have been lucky but I have never had a basket fail but I haven't ever kept a bike with more than 40K miles on the clock . I have had a sprag fail on a Aprilia after 20k miles so I suppose I am more concerned about the gear attached to the basket than the basket itself..I did in the early 80s have a t140v as it was the only big bike my meagre apprentice wages could afford when I sold my LC. I had it re-bored because it smoked more than my grandad and fitted a new rectifier and apart from oil changes and basic servicing then that was it in 20K miles . I sold the bike with 32K on it so maybe I am looking for problems that don't exist. Another one of life's sneaky aging tricks .

 

[Rancidpegwoman]

Hi MPH,
I always use the anodised alloy clutch basket, it does not wear notches in the slots where the clutch plates sit as easily as steel. The chainwheel teeth seem to last longer. But this is not my primary reason for purchase, the alloy basket is much lighter than the steel, therefore carries less inertia, and requires less energy to spin up. The alloy basket seems more stable than the steel.

Alloy clutch sprocket 650 duplex

Alloy clutch sprocket 650 duplex

www.triumph-spares.co.uk

The 7 plate conversion will certainly work well for you, once fitted remember to readjust the pushrod clearance after 250 or so miles, the plates will bed in and reduce the clearance quickly in the beginning, but then will settle down after the 250 mile adjustment.
As you probably know from your T140 days initial setting up of the clutch is a balancing act of adjustment, do them right in the correct order and you will have a nice action, non dragging, non slipping clutch. Get the adjustments wrong and you will have a horrorshow of a gearchange.
If you want the best description of how to set the clutch up correctly, then search for previous posts by @TR7RVMan on the subject.
The centre hub might have notches worn in by the previous clutch plates, if severe replace, if light file smooth, making sure the slots are evenly filed. Behind the clutch centre is a thrust washer, this will almost certainly benefit from replacement.
The working life of duplex (and triplex) primary chains appears to be greatly affected by correct alignment of the sprockets, Triumph placed shims behind the crankshaft sprocket to allow you to adjust the position of the sprocket, try to get the alignment within 0.005" (5 thou) for chain longevity.
The engine and primary share oil on the 72, so it is important to choose an engine oil that is suitable for wet clutches, these will be motorcycle specific oils, often labeled 4T, there should be a JASO ma/mb rating in the specification. Car grade oils should not be used as they have friction modifiers that will make your clutch slip.

best regards
Peg.

 

[StuartMac]

Hi,

you think I am better to stick with the existing rotor and stator or at least their outputs if I replace them

Imho:-

. First put some miles on the bike, to see if there are any charging problems using the bike as you want. If no problems, whatever state the rotor and stator are in, they're adequate for what you want?

. If you do replace, with the high-output version of the 3-phase; it doesn't make any financial sense to replace with anything else - there's only one new rotor, stators cost pretty-much the same whatever their output so the high-output 3-phase is the "most bang for your buck":-

.. While the existing loom Brown/Blue cable is only rated for 8.75A, the basic principle of any reg./rec. is, irrespective of stator output at any given rpm, a reg./rec. only rectifies enough to satisfy the DC 'demand'. You've connected the reg./rec. DC cables directly to the corresponding battery terminals? If yes, only the ignition and lighting are being supplied through the loom Brown/Blue wire; the ignition (should) only draw(s) 4A max., LED lighting, the existing wire's 8.75A capacity shouldn't be exceeded.

.. Any stator output not rectified is turned into heat; however, realistically, because even the high-output 3-phase is only rated for 14.5A @ 5,000 rpm, ignition and lighting powered, battery kept charged, any excess stator output turned into heat is only a few Amps. If you decide you want to use any of a high-output 3-phase stator's unused output to power something else, you know there's a point where you might have to replace some loom wires with thicker.

Considering the future, if/when you want or have to sell the bike, the MOSFET reg./rec. fitted already is an advantage, high-output 3-phase if added would be another one.

thoughts re the life expectancy of the primary drive sprockets

Mmmm ... personally, I wouldn't change a chain without changing the sprockets - new chain on worn sprockets wears the components faster, worn chain on new sprockets wears the components faster. However, define "faster" - if you change just the engine sprocket now, although all three components are worn differently, if you do only cover "circa 3-4000 miles per annum", there might still be two or more years' life in, say, the chain?

However, were I to change both engine sprocket and clutch basket, I believe I'd fit a new chain as well; any used components (sprocket, basket, chain) not showing obvious wear, I'd put on Ebay with the use information in the advert. description.

Hth.

Regards,

 

[mph dawson]

Hi MPH,
I always use the anodised alloy clutch basket, it does not wear notches in the slots where the clutch plates sit as easily as steel. The chainwheel teeth seem to last longer. But this is not my primary reason for purchase, the alloy basket is much lighter than the steel, therefore carries less inertia, and requires less energy to spin up. The alloy basket seems more stable than the steel.

Alloy clutch sprocket 650 duplex

Alloy clutch sprocket 650 duplex

www.triumph-spares.co.uk

The 7 plate conversion will certainly work well for you, once fitted remember to readjust the pushrod clearance after 250 or so miles, the plates will bed in and reduce the clearance quickly in the beginning, but then will settle down after the 250 mile adjustment.
As you probably know from your T140 days initial setting up of the clutch is a balancing act of adjustment, do them right in the correct order and you will have a nice action, non dragging, non slipping clutch. Get the adjustments wrong and you will have a horrorshow of a gearchange.
If you want the best description of how to set the clutch up correctly, then search for previous posts by @TR7RVMan on the subject.
The centre hub might have notches worn in by the previous clutch plates, if severe replace, if light file smooth, making sure the slots are evenly filed. Behind the clutch centre is a thrust washer, this will almost certainly benefit from replacement.
The working life of duplex (and triplex) primary chains appears to be greatly affected by correct alignment of the sprockets, Triumph placed shims behind the crankshaft sprocket to allow you to adjust the position of the sprocket, try to get the alignment within 0.005" (5 thou) for chain longevity.
The engine and primary share oil on the 72, so it is important to choose an engine oil that is suitable for wet clutches, these will be motorcycle specific oils, often labeled 4T, there should be a JASO ma/mb rating in the specification. Car grade oils should not be used as they have friction modifiers that will make your clutch slip.

best regards
Peg.

Thanks Peg , any information regarding how to correctly align the sprockets would be very much appreciated.In respect to the clutch I have bitten the bullet and purchased an alloy one along with a new rotor and stator Oil I have been use Morris but again happy to learn from those who can recommend from experience of knowing what works best.

Hi,

Imho:-

. First put some miles on the bike, to see if there are any charging problems using the bike as you want. If no problems, whatever state the rotor and stator are in, they're adequate for what you want?

. If you do replace, with the high-output version of the 3-phase; it doesn't make any financial sense to replace with anything else - there's only one new rotor, stators cost pretty-much the same whatever their output so the high-output 3-phase is the "most bang for your buck":-

.. While the existing loom Brown/Blue cable is only rated for 8.75A, the basic principle of any reg./rec. is, irrespective of stator output at any given rpm, a reg./rec. only rectifies enough to satisfy the DC 'demand'. You've connected the reg./rec. DC cables directly to the corresponding battery terminals? If yes, only the ignition and lighting are being supplied through the loom Brown/Blue wire; the ignition (should) only draw(s) 4A max., LED lighting, the existing wire's 8.75A capacity shouldn't be exceeded.

.. Any stator output not rectified is turned into heat; however, realistically, because even the high-output 3-phase is only rated for 14.5A @ 5,000 rpm, ignition and lighting powered, battery kept charged, any excess stator output turned into heat is only a few Amps. If you decide you want to use any of a high-output 3-phase stator's unused output to power something else, you know there's a point where you might have to replace some loom wires with thicker.

Considering the future, if/when you want or have to sell the bike, the MOSFET reg./rec. fitted already is an advantage, high-output 3-phase if added would be another one.


Mmmm ... personally, I wouldn't change a chain without changing the sprockets - new chain on worn sprockets wears the components faster, worn chain on new sprockets wears the components faster. However, define "faster" - if you change just the engine sprocket now, although all three components are worn differently, if you do only cover "circa 3-4000 miles per annum", there might still be two or more years' life in, say, the chain?

However, were I to change both engine sprocket and clutch basket, I believe I'd fit a new chain as well; any used components (sprocket, basket, chain) not showing obvious wear, I'd put on Ebay with the use information in the advert. description.

Hth.

Regards,

Thanks Stuart I have decided to replace all the contents of the primary case and I have ordered a new stator and rotor , engine sprocket, gearbox sprocket oil seal and alloy clutch , it should ( assuming I assemble it properly) see me out . I decided to stick with the RM20 rotor and RM21 stator as I have already experienced a melting loom and having read your earlier response was worried re the prospect of all my hard work going up in smoke because as you pointed out the cables weren't rated in line with the potential output. I have since read your latest response which seems to now say the cables will be fine but hopefully I have made the right decision . I wont be attaching a sat nav or any other power hungry gizmos to the bike so really I suppose I simply need enough power to create a spark and power the indicators and brake lights .Here's a question for you Stuart as you seem to know an awful lot more about electrics than I do. I can follow a diagram and that is about it . I have noticed that my indicators are slow when the engine is revved and I am travelling at higher speeds but as I return to normal speed at lower revs they operate as I would expect . Could this be a dodgy flasher unit or is this a symptom of needing 3 phase and therefore maybe my thinking re the RM20/21 Rotor and Stator is already flawed

 

[Rancidpegwoman]

Thanks Peg , any information regarding how to correctly align the sprockets would be very much appreciated.In respect to the clutch I have bitten the bullet and purchased an alloy one along with a new rotor and stator Oil I have been use Morris but again happy to learn from those who can recommend from experience of knowing what works best.

Hi
The sprocket alignment is simple, assemble and fit the clutch thrust washer/20 roller bearings/basket and hub, nip up the gearbox mainshaft nut, not too tighr as you don’t want to lock it hard on the taper fit yet. Do not worry if it feels wobbly, they are all wobbly.
fit the engine sprocket pushed back hard on the crankshaft (do not fit the primary chain), hold the clutch basket hard agai the thrust washer and place a straight edge between the sprocket teeth and the clutch basket teeth, if you have no shims there is likely to be a gap at the sprocket end. Remove the engine sprocket and add the shims in thickness combinations between the crankshaft and sprocket. When you can place the straight edge between the two sets of teeth, without a gap (with 5 thou) alignment is complete.
you are then set to assemble the complete clutch assembly.

I would only use the set up method used by @TR7RVMan, he has explained it on several previous occasion, so it is easy to find, and it is a foolproof method.

Morris oils are odd, either you have used 20w50 golden film heritage oil or 20w50 Race V twin motorcycle oil.
The race Vtwin is Jaso MB rated so should not make your clutch slip.
The golden film is a low additive low detergent oil, so might not have the friction modification additives that make the clutch slip. The low detergent means that it is designed to drop contamination out of the oil to form a sludge at the bottom of the oil tank, the old fashioned way.
A high detergent oil will hold contamination in the oil, to be removed by a modern oil filter, there are several aftermarket add on Filter assembly’s available.

Personally if I was using Morris oils, I would use the Race V Twin 20w50 in the engine and primary drive. It is Jaso rated and designed for motorcycle.
If I was thinking of using the Golden Film 20w50, I would contact Morris Lubricants and seek reassurance that the clutch will not be affected (Slip).

Regards
Peg.

 

[mph dawson]

Hi
The sprocket alignment is simple, assemble and fit the clutch thrust washer/20 roller bearings/basket and hub, nip up the gearbox mainshaft nut, not too tighr as you don’t want to lock it hard on the taper fit yet. Do not worry if it feels wobbly, they are all wobbly.
fit the engine sprocket pushed back hard on the crankshaft (do not fit the primary chain), hold the clutch basket hard agai the thrust washer and place a straight edge between the sprocket teeth and the clutch basket teeth, if you have no shims there is likely to be a gap at the sprocket end. Remove the engine sprocket and add the shims in thickness combinations between the crankshaft and sprocket. When you can place the straight edge between the two sets of teeth, without a gap (with 5 thou) alignment is complete.
you are then set to assemble the complete clutch assembly.

I would only use the set up method used by @TR7RVMan, he has explained it on several previous occasion, so it is easy to find, and it is a foolproof method.

Morris oils are odd, either you have used 20w50 golden film heritage oil or 20w50 Race V twin motorcycle oil.
The race Vtwin is Jaso MB rated so should not make your clutch slip.
The golden film is a low additive low detergent oil, so might not have the friction modification additives that make the clutch slip. The low detergent means that it is designed to drop contamination out of the oil to form a sludge at the bottom of the oil tank, the old fashioned way.
A high detergent oil will hold contamination in the oil, to be removed by a modern oil filter, there are several aftermarket add on Filter assembly’s available.

Personally if I was using Morris oils, I would use the Race V Twin 20w50 in the engine and primary drive. It is Jaso rated and designed for motorcycle.
If I was thinking of using the Golden Film 20w50, I would contact Morris Lubricants and seek reassurance that the clutch will not be affected (Slip).

Regards
Peg.

Thanks ever so Peg, I am using the Race V twin version- out of interest what do you use? Right back to the alignment I think I understand, but I can see that it will be fiddly for one pair of untrained hands. Holding a feeler gauge in one hand with a steel rule in the other is about as close as I will ever get to multi-tasking. Anyway I had better clean my glasses and have a go .I can't find the shims in my catalogue so would you happen to have a part number for each of the varying thicknesses or are they simply called engine sprocket shims and the folks at my friendly supplier will know exactly what I require .Presumably I have to buy and stock a range of them and you can only shim from the engine sprocket side, where the sprocket meets the main bearing? Naively I thought I was making it easier for myself by purchasing an assembled alloy clutch basket,.I thought it was a case of simply exchanging everything and I would have everything stripped and reassembled by close of play on Saturday but I am beginning to think that will be wishful thinking .I have a couple more questions if you don't mind When you say not too tight, then if you were to throw a number at a torque setting for not too tight then what would it be? Do you recommend loctite for the reassembly or do I simply rely on the tab washers/nuts. Normally i would use loctite blue 242 for the clutch .Finally if I was to measure the thickness of the existing engine and clutch sprockets and compare them to their replacements and assume it was set up correctly previously then could I work out the required shim thickness from the differences or is that just wishful thinking? Thank you for your help and if you ever decide to buy an Aprilia Mille and you need some advice I may be your man!

 

[Rancidpegwoman]

Hi
I’m using an Australian oil Penrite, but it is very hard to get hold of in the UK. I eventually managed to get a 205 litre barrel.
The Morris Race V twin looks good.
I had better clarify that the ’not too tight’ was only for measuring the chain offset, so that the sprockets/hub is held in place and can be popped on and off easily for adjustment, it is just nipped up to take out the play. For final assembly the nuts have to be fully tightened. (30 lb ft for the alternator nut, 50 lb ft for the clutch hub nut).
I have got into the habit of lapping the hub on to the mainshaft, using a little fine grinding paste, then solvent cleaning it thoroughly after completion, thoroughly means about 10 times, grinding paste left inside the engine is instant destruction.
This involves temporarily removing the woodruff key, manually lapping the hub to the shaft so they both have a matt grey unbroken finish, clean,clean,clean, clean, then refit the woodruff key ready for final assembly. The clutch hub and mainshaft will never break away after this. But be aware if you have done this, removal of the hub at a later date will be a lot harder to achieve.

I don’t use loctite inside the primary.

70-8038 = 10thou shim,
71-2660 =30 thou shim.
Type these numbers and Triumph into your web browser to find retailers.

I would never assume anything is correctly set up on these old bikes, 51 years of idiot previous owners will certainly prove you wrong with any assumptions. Measuring is the only way.
I am not even sure that the T120 was originally shimmed, it may have only been introduced when the very sensitive to alignment triplex chain was introduced in 73, but the method still works well for the duplex chain, enhancing chain and sprocket life.

Nothing is plug and play on these old bikes, Triumph generously allows you set them up so they are a delight to ride, or allows you to set them up so you are permanently on the road to hell.

regards
Peg.

 

[StuartMac]

Hi,

have already experienced a melting loom and having read your earlier response was worried re the prospect of all my hard work going up in smoke because as you pointed out the cables weren't rated in line with the potential output. I have since read your latest response which seems to now say the cables will be fine

Then I've inadvertently given you the wrong impression:-

. While modern metric 14-strand cable is rated for 8.75A, empirical evidence suggests at least European wire ratings have something like a 50% 'safety margin'; i.e. metric 14-strand can probably carry up to ~13A without damage.

. The empirical evidence is: '71-on, Lucas supplied Triumph and BSA with looms having all 14-strand cables, including the Brown/Blue between rectifier and Zener diode:-

.. this 14-strand was Imperial, rated for only 7.5A because each strand was slightly smaller than metric;

.. however, the RM21 is rated for 10.5A @ 5,000 rpm and it produces 75% of rated (a gnat's under 8A) @ 2,400 rpm; i.e. most '71-on Britbikes operated with the 7.5A wire rating exceeded most of the time, most with few or no problems;

.. however2, I do know that some owners used '71-on triples with Lucas Rita electronic ignition with three '12V' ignition coils connected in parallel; this could draw up to 12A and some owners experienced the '71-on 14-strand Brown/Blue turn brown/crispy ... ... i.e. any "safety margin" was exceeded somewhere above 11A?

In your bike's case, although in theory a 14-strand metric wire's 8.75A could be exceeded by a 14.5A @ 5,000 rpm high-output stator, in practice:-

. the loom doesn't turn into a molten mess at 8.76A;

. because you've fitted a reg./rec.:-

.. if the rec./rec. DC wires are connected directly to the corresponding battery terminals, the loom Brown/Blue wire won't carry battery-charging Amps;

.. DC input Amps along the Brown/Blue won't exceed that drawn by ignition and lighting; because you've fitted LED lighting, I can't see ignition and lighting drawing more than 8.75A but, even if it did for short periods, you'd struggle to get it to exceed ~13A?

noticed that my indicators are slow when the engine is revved and I am travelling at higher speeds but as I return to normal speed at lower revs they operate as I would expect

Mmmm ... that's an odd one ... my experience is the other way 'round - some flasher units speed up the flash rate as the engine rpm rises, rate returns to 'normal' at lower rpm. Incandescent or LED flashers?

If LED, have you added resistors so a 'standard' flasher unit works them, or is the flasher unit for LED?

Either type of flasher, do they have both a supply and return wire, or are their returns (to the battery 'earth' terminal) through their mountings on the bike and painted or rubber-mounted other parts?

symptom of needing 3 phase

Uh-uh. Flashers are only used intermittently, I consider them (and the horn) powered by the battery, there should be charging system capacity that keeps the battery charged but be aware that there might not be at low rpm.

Hth.

Regards,

 

[mph dawson]

Hi
I’m using an Australian oil Penrite, but it is very hard to get hold of in the UK. I eventually managed to get a 205 litre barrel.
The Morris Race V twin looks good.
I had better clarify that the ’not too tight’ was only for measuring the chain offset, so that the sprockets/hub is held in place and can be popped on and off easily for adjustment, it is just nipped up to take out the play. For final assembly the nuts have to be fully tightened. (30 lb ft for the alternator nut, 50 lb ft for the clutch hub nut).
I have got into the habit of lapping the hub on to the mainshaft, using a little fine grinding paste, then solvent cleaning it thoroughly after completion, thoroughly means about 10 times, grinding paste left inside the engine is instant destruction.
This involves temporarily removing the woodruff key, manually lapping the hub to the shaft so they both have a matt grey unbroken finish, clean,clean,clean, clean, then refit the woodruff key ready for final assembly. The clutch hub and mainshaft will never break away after this. But be aware if you have done this, removal of the hub at a later date will be a lot harder to achieve.

I don’t use loctite inside the primary.

70-8038 = 10thou shim,
71-2660 =30 thou shim.
Type these numbers and Triumph into your web browser to find retailers.

I would never assume anything is correctly set up on these old bikes, 51 years of idiot previous owners will certainly prove you wrong with any assumptions. Measuring is the only way.
I am not even sure that the T120 was originally shimmed, it may have only been introduced when the very sensitive to alignment triplex chain was introduced in 73, but the method still works well for the duplex chain, enhancing chain and sprocket life.

Nothing is plug and play on these old bikes, Triumph generously allows you set them up so they are a delight to ride, or allows you to set them up so you are permanently on the road to hell.

regards
Peg.

 

[mph dawson]

Hi,

Then I've inadvertently given you the wrong impression:-

. While modern metric 14-strand cable is rated for 8.75A, empirical evidence suggests at least European wire ratings have something like a 50% 'safety margin'; i.e. metric 14-strand can probably carry up to ~13A without damage.

. The empirical evidence is: '71-on, Lucas supplied Triumph and BSA with looms having all 14-strand cables, including the Brown/Blue between rectifier and Zener diode:-

.. this 14-strand was Imperial, rated for only 7.5A because each strand was slightly smaller than metric;

.. however, the RM21 is rated for 10.5A @ 5,000 rpm and it produces 75% of rated (a gnat's under 8A) @ 2,400 rpm; i.e. most '71-on Britbikes operated with the 7.5A wire rating exceeded most of the time, most with few or no problems;

.. however2, I do know that some owners used '71-on triples with Lucas Rita electronic ignition with three '12V' ignition coils connected in parallel; this could draw up to 12A and some owners experienced the '71-on 14-strand Brown/Blue turn brown/crispy ... ... i.e. any "safety margin" was exceeded somewhere above 11A?

In your bike's case, although in theory a 14-strand metric wire's 8.75A could be exceeded by a 14.5A @ 5,000 rpm high-output stator, in practice:-

. the loom doesn't turn into a molten mess at 8.76A;

. because you've fitted a reg./rec.:-

.. if the rec./rec. DC wires are connected directly to the corresponding battery terminals, the loom Brown/Blue wire won't carry battery-charging Amps;

.. DC input Amps along the Brown/Blue won't exceed that drawn by ignition and lighting; because you've fitted LED lighting, I can't see ignition and lighting drawing more than 8.75A but, even if it did for short periods, you'd struggle to get it to exceed ~13A?



Mmmm ... that's an odd one ... my experience is the other way 'round - some flasher units speed up the flash rate as the engine rpm rises, rate returns to 'normal' at lower rpm. Incandescent or LED flashers?

If LED, have you added resistors so a 'standard' flasher unit works them, or is the flasher unit for LED?

Either type of flasher, do they have both a supply and return wire, or are their returns (to the battery 'earth' terminal) through their mountings on the bike and painted or rubber-mounted other parts?


Uh-uh. Flashers are only used intermittently, I consider them (and the horn) powered by the battery, there should be charging system capacity that keeps the battery charged but be aware that there might not be at low rpm.

Hth.

Regards,

Thanks I will investigate further

 

[mph dawson]

hi Peg, when I am assembling the two sprockets to check their alignment prior to shimming and final assembly then I am presuming there is no need to insert the woodruff keys until I am happy the alignment is within spec. By the way I can see that you are a proper old skool craftsperson ,so fair play with the lapping ! Personally I have always put blue Loctite on clutch nuts and I will probably put a dab on the screws that hold the gearbox sprocket cover plate too,.I will not bother with the rotor or anything else on the bike that either employs a locknut or a folded tab washer. Everything else is fair game to me, otherwise I will suffer with a unhealthy level of paranoia for the first 500 miles after the rebuild Most of the parts have arrived today and the clutch looks quality but so do some knock off watches so I suppose only time tells. Anyway all being well I should be able to make a good dint in the project on Saturday

 

[mph dawson]

Hi All, quick question I have fitted the new gearbox final drive sprocket and after tightening there is a small amount ( maybe a mm )of side to side play , I can't nip it anymore. Is this normal , thought I had better ask prior to refitting everything else ?

 

[mph dawson]

Hi,

Then I've inadvertently given you the wrong impression:-

. While modern metric 14-strand cable is rated for 8.75A, empirical evidence suggests at least European wire ratings have something like a 50% 'safety margin'; i.e. metric 14-strand can probably carry up to ~13A without damage.

. The empirical evidence is: '71-on, Lucas supplied Triumph and BSA with looms having all 14-strand cables, including the Brown/Blue between rectifier and Zener diode:-

.. this 14-strand was Imperial, rated for only 7.5A because each strand was slightly smaller than metric;

.. however, the RM21 is rated for 10.5A @ 5,000 rpm and it produces 75% of rated (a gnat's under 8A) @ 2,400 rpm; i.e. most '71-on Britbikes operated with the 7.5A wire rating exceeded most of the time, most with few or no problems;

.. however2, I do know that some owners used '71-on triples with Lucas Rita electronic ignition with three '12V' ignition coils connected in parallel; this could draw up to 12A and some owners experienced the '71-on 14-strand Brown/Blue turn brown/crispy ... ... i.e. any "safety margin" was exceeded somewhere above 11A?

In your bike's case, although in theory a 14-strand metric wire's 8.75A could be exceeded by a 14.5A @ 5,000 rpm high-output stator, in practice:-

. the loom doesn't turn into a molten mess at 8.76A;

. because you've fitted a reg./rec.:-

.. if the rec./rec. DC wires are connected directly to the corresponding battery terminals, the loom Brown/Blue wire won't carry battery-charging Amps;

.. DC input Amps along the Brown/Blue won't exceed that drawn by ignition and lighting; because you've fitted LED lighting, I can't see ignition and lighting drawing more than 8.75A but, even if it did for short periods, you'd struggle to get it to exceed ~13A?


Mmmm ... that's an odd one ... my experience is the other way 'round - some flasher units speed up the flash rate as the engine rpm rises, rate returns to 'normal' at lower rpm. Incandescent or LED flashers?

If LED, have you added resistors so a 'standard' flasher unit works them, or is the flasher unit for LED?

Either type of flasher, do they have both a supply and return wire, or are their returns (to the battery 'earth' terminal) through their mountings on the bike and painted or rubber-mounted other parts?


Uh-uh. Flashers are only used intermittently, I consider them (and the horn) powered by the battery, there should be charging system capacity that keeps the battery charged but be aware that there might not be at low rpm.

Hth.

Regards,

Hi Stuart , Alternator , clutch etc. fitted this afternoon, voltmeter reads 14.36v with the lights off at circa 2k revs. Indicators now speed up now as revs increase before returning to normal.at tickover. The flasher unit has a rubber mount and is connected up exactly as the wiring diagram. would you suggest replacing the flasher unit or is the problem likely to elsewhere. I fitted a replacement loom LED headlight,though the indicators use normal bulbs. All other functions work as they should . All returns are via the mountings on the bike.

 

[StuartMac]

Hi,

Indicators now speed up now as revs increase before returning to normal.at tickover. The flasher unit has a rubber mount and is connected up exactly as the wiring diagram. would you suggest replacing the flasher unit

I experienced very similar symptoms when I tried similar cheap flasher units in place of the standard Lucas 8FL. I reverted to Lucas but what's called the 9FL (Lucas supplied it to British makers of vehicles except bikes to work the flashers in 'hazard' mode). Apart from being deeper, a 9FL's the same dimensions as an 8FL, so the 9FL fits in the standard anti-vibe mount; despite it's capable of flashing four incandescent bulbs plus idiot warnings, ime they seem quite happy flashing a bike's two flashers and single idiot warning. Only thing to watch in the US is common incandescent flasher bulbs are 23W whereas certainly the original Lucas 8FL and 9FL were made for standard European 21W flasher bulbs.

returns are via the mountings on the bike.

When (not if ime) that begins to give trouble, the flash rate slows 'til eventually they don't at all - the problem is increasing resistance in the return is in series with the bulbs' standard resistance.

voltmeter reads 14.36v with the lights off at circa 2k revs.

Fwiw, I'd always check - engine rpm increased, at what rpm do the Volts stop increasing with increasing rpm? Should be no more than 15V somewhere between 3,500 and 4,000 rpm.

Hth.

Regards,

 

[mph dawson]

Hi Stuart,

I am not sure who fitted the flasher unit but it is obviously generic as it is called super winker . I have ordered a full replacement Lucas assembly(unit,bracket and spring) and now I simply have to work out the best place to fit it. This is because I removed the old airbox set up and replaced it with the more classically designed side panels so I could either mount it in the tool tray if there is room ( I have the electronic ignition there )or possibly make a longer bracket to put it in line with the Mofset(my preference) so it is hidden under the right hand side panel. Once fitted and assuming I can work out how to hand crimp my new rev counter bezel I will also take your advice and see whether the voltage stops rising at circa 3.5-4K rpm .