coils

[milne]

hi steviep,
                thought ide ask a question on a new thread,rather than hi-jacking toledos thread. by the way its been very informative with u and others working thru his problems..
 my question is,  did ti40s come out standard with 12 volt coils,did any come out standard with 6 volt ?  and with introducing an electronic ignition system, why is there a need to convert to 6 volt coils ?
 so i can understand it properly,what is the difference between both types as far as special tuning or differences in set up,, i no mine had boyer installed when i bought it and had 12 volt coils ?
                           cheers colin

[gumpt1oo]

Hi Colin,
StevieP will know the reasons why the some systems have 12v and others 6v, I am not sure why, I am no expert with this electrickery!
My manual says that  the TR65, TR7V and T140V (+ earth) all came with 12volt coils.
all other models had 6volt coils.

Steve

[steviepope2000]

Hi Guys,
As Steve says, the T140 had 12v coils as standard. In Pauls case though, given that the bike is approaching 40 years old, who knows what a PO may have done to the wiring?
The coils changed to 6v with the introduction of the T140E and its fitment of Lucas RITA electronic ignition. I'm not sure about the new wave of EI (30 years on) we have mentioned recently (Pazon, Tri-Spark, Sparx, etc. as looking at their instructions give an array of 6v, 12v, Jap 12v twin output, etc. coils) but the early ones were designed to trigger just the once, when both pistons are nearly at TDC and using the waste spark method, thus keeping the design and moving parts to a minimum. This would still work by triggering both 12v coils at the same time but I believe there are another couple of points.
The EI requires power to the 'AB11' amplifier box (whereas points are basically an on/off switch, triggering the coil field, and consume zero'ish power to do this) and the introduction of the halogen headlight on the T140E also increased power consumption. They increased the alternator output on this model, but not the battery size and 2 x 6v coils in series apparently aids starting and use less power and you can see that a few of the new EI suppliers even recommend (and obviously supply) 2 x 6v coils as the best option in their tech blurb.
Hope this sheds some light, but it is as I understand it from bits here and there over the years, not in writing.
I'm not an electrician either - but our old Triumphs are fairly basic and understandable.
Stevie.P

[Ed Sidders]

Colin
While I'm thinking about it-------------Done any good on your bike yet

[milne]

thanks for that steviep, very informative..
  hey tex,  my bike is still back at his shop,he has it for sale as he cant afford to refund me..ill give him till septemberish,if he hasnt sold it,,im going to take it back and do a restoration etc.
 he still cant fix the richness problem,but hes got it on his website for sale...its at central motorcycles,under triumph for sale,,hes got 10k on it..its the pale blue tank one ,if u look..
  yeah real frustrating,but i cant afford to buy another until he pays me for that one,,but as i said,septemberish and ill cut my losses and take it back and work on it myself..
                         cheers   colin

[spartan]

I  am having a bit of trouble with my T140 and have changed all the electrics including the ignition,
I rang Boyer who make the electronic ignition i fitted and asked them if 6 v cols are better on the T140 and yes they are better spark wired the same as the 12 v.

I am know setting about the carbs.

[steviepope2000]

I rang Boyer who make the electronic ignition i fitted and asked them if 6 v cols are better on the T140 and yes they are better spark wired the same as the 12 v.

I definately wouldn't replace 12v coils with 6v and leave the wiring the same, not unless the 12v coils were incorrectly wired in the 1st place (in which case they were working poorly at 6v). The bike is 12v, so to run 12v coils they need to be wired in parallel, so each gets 12v supply. To run 6v coils they are wired in series, the 12v supply goes in to the 1st coil and out to the 2nd coil. The 1st takes 6v and the other 6v carries on to the 2nd. If you left them wired as for 12v then each would be fed 12v (twice its design level) and not last very long before failing.
(If anyone would like a simple diagram to help clarify the above I can add to post).
Stevie.P

[spartan]

Thats what i thought but the Boyer man said different due to the system using the waste spark system.
The first coil gets 12v and the second half the voltage. Weird i thought but i checked the diagram that comes with the system and its right..

Pete

[steviepope2000]

Hi Pete
I assume you have the Mk IV Kit00052? and can now look forward to years of adjustment & replacement free use, unlike points. You may even notice a real difference (once you can sort your present problem) as the timing advance will be much more precise than the vague mechanical advance unit you have ditched. 
I have looked at the wiring diagram and the fitting details and it explains how you link the wiring and modify to make the coils fed in series and so each gets 6v. They do say 12v coils are ok like this for road use, which for someone with 12v coils already saves some money. If I had to replace them in the future though I'd go for 6v ones which will obviously perform better at the correct design voltage.
As for the "one can have 12v and the other 6v", I think in polite circles I'd cough while stating "Bullsh*t", unless the wiring had been rigged with resistors or something.  
As for 'waste spark', as I've answered recently, that is the way EI normally works, it simplifies things by only having only one sparking trigger point (just before TDC) for both cylinders (hence the coils in series, to fire both), whereas there were two sets of points triggering each cylinder independently. The rotor has two trigger points on it but that is because the camshafts turn at half crankshaft speed.
Stevie.P

[bonnevillebill]

As a general rule, electronic ignitions use 6v coils, wired in series; Points type ignition uses 12v coils, wired individually through the points set for that coil.
Here's how it works:
Triumphs are 360 degree twins. That means that both pistons move up and down at exactly the same height. When one is at top dead centre, so is the other one (Some twins, such as the Honda CB350/360/450s are 180 degree twins with one at bottom dead centre while the one beside it is at top dead centre, like bicycle pedals, but not Triumphs, not BSA's not Nortons.)

On the Triumph, as both pistons are approaching top dead centre at the same time, one piston is on its compression stroke. (it has sucked in petrol and air mixture, both valves are closed, and it is getting ready to fire.)  The other piston is on its exhaust stroke (It has just fired, the exhaust valve has just opened and the piston is pushing the exhaust gases up and out the open valve.)

At this point on an engine fitted with points, one of the two sets of points is about to open (the one with the piston on its compression stroke). At the instant that the points open, that 12v coil will fire through the spark plug and ignite the compressed mixture in that cylinder. On the next turn of the engine, it will be this piston that travels through the exhaust stroke and the other points-set/coil/plug/cylinder will fire. In other words, one plug fires, then, 360 degrees of crank rotation later, the other one fires, 360 one, 360 the other, ad infinitum.

Now at  this point on an engine with electronic ignition, a magnetic trigger on a rotor (that lives in the same place as the points did...or do) is about to pass the reluctor, at which point BOTH COILS are going to fire SIMULTANEOUSLY. One side will have compressed mixture in the combustion chamber and will light off. The other side will have its exhaust valve closing, it's intake valve just ready to open (to suck in more mixture) and the spark from that plug will have nothing to ignite. So each 360 degrees of crank rotation, both plugs fire together, each and every time.

 The spark in the side that has no mixture is the "wasted" spark. The coils are wired in series.  When one plug sparks, so does the other one. This means that the electricity passes from the electronic amplifier (the 'brain box') then through one coil, the through the other coil, and then to ground. The two 6v coils, wired in series, provide the same resistance as one 12 volt coil. (ie, the 12 volts from the bikes electrical system simply would not pass through two 12v coils and produce 2 simultaneous sparks.

[milne]

hey bonnevillebill,
                          great explanation on coils.
   in your opinion, if a bike fitted with 12 volt coils,,( 78 t140e ) is convertated to a boyer ei system,would it be correct in saying its best to change over to 6v coils  ?.  or in your opinion can the 12v be left and trusted to do the same job, or could there be some inherent problems by not changing to 6v  ?
                                   colin

[bonnevillebill]

Hi Colin,
I believe that the Boyer unit will need 6volt coils. My1979 t140D has a Lucas RITA (6v coils), has been trouble-free all these years. I would check with Boyer and go with what they recommend. I had a Boyer set up on my old T150V trident years ago. I had a bit of trouble with getting it working initially and remember getting up to call them at 4:30 AM. I'm in Pennsylvania and this was back in the days before Skype, when different rates applied at different times of day and phoning the UK was expensive. Anyhow, it would be 9:30 over there. The people at Boyer were very friendly and helpful, had me up and running in no time so, I'd follow the  instruction sheet that came with your or, if it doesn't tell you or you somehow lost the sheet, give them a call. They're good folks (or they were back when I had my Trident).
Bill
PS I have seen a lot of after market 2 lead coils and have been told that they work well with this sort of application. Once again, though, if I were doing the job I'd give Boyer a call rather than listening to me.

[milne]

hey bonnevillebill,
                            thanks for that,mine is a long saga,as u might have seen on other threads,the bike is back with seller to resell,but im only giving him another month or so to sell,if he doesnt ill take it back and try and fix it myself....  he fitted the boyer on when i bought it, and i believe he said he fitted new coils 12 volt.. after a new head etc it still has major richness problems he still cant fix and hes trying to resell it as is is,anyway i wont go into the saga its all on previous threads,  but if i cut my losses and take it back ill be starting from scratch with it.  maybe hes had success with sticking to 12 volt coils when converting to electronic ignition,but it seems from yours and steviep response that changing to 6 volt is better, its just another bit of thought for a first timer like myself to consider and its great to here others with more experience. and who knows,this could be where i need to start to solve its problems,,  apart from him putting smaller main jet sizes in,which wont stop the richness in my opinion cause the main jet doesnt come into play until at least half throttle,he sais hes now done everything on the carb,but no change.
  anyway food for thought as they say..  cheers for your comments
                                        colin
                                melbourne

[Jef Davies]

Hey , Bill, Thank you very much for the post --This was all very instructive  & can provide some overview that is not usually heard --Thanks again for posting ---In this site we are all friends, ( or banned ) --if there is is ever a seemingly contradictory post , I just can say that we are all here together--M of M -- It might be OK to take the bike back, but you are talking in an open forum, I would hate to have your thoughts transmitted to the dealer of disappointment, and if He is reading this, I should say, we can mention you by name , on the world wide web....I think the carbs were boiled with the choke plungers in  , and  they were destroyed--nobody wants to buy new ones , as the cost fifty bucks apiece       

[milne]

hey jeff,
             i agree with u its good to get everyones imput and ideas, i can honestly say just reading thru the forum as a novice my understanding of bonnevilles has greatly improved.
  ....and i certainly do hope the dealer browses thru the forum,maybe as one of those obscured visitors perhaps,,  hey jeff,maybe like me he will actually learn something  !!!
   anyways  its another good informative subject to read about,  thanks again
                             colin
                           m of m