The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Lucas, Ignition, Charging, Electrical => Topic started by: Ewen on 14.09. 2021 20:21
-
I may have an intermittent mag problem. I am considering putting on the Thorspark electronic ignition system. Is it any good.
-
I think it is, Ewen. (Good, that is.)
Very low current consumption (critical on dynamo bikes some would say!), runs on a wasted spark so you don't have to worry about whether the timing's the same on both sides, quite hard to spot on the bike if done neatly (if the original look is important), reasonably priced and not hard to fit.
Were I not a bit one-eyed and biased in favour of magnetos, I'd probably have one on something or other - and if I had a V twin I definitely would!
-
I think it is, Ewen. (Good, that is.)
Very low current consumption (critical on dynamo bikes some would say!), runs on a wasted spark so you don't have to worry about whether the timing's the same on both sides, quite hard to spot on the bike if done neatly (if the original look is important), reasonably priced and not hard to fit.
Were I not a bit one-eyed and biased in favour of magnetos, I'd probably have one on something or other - and if I had a V twin I definitely would!
Why more so on a V twin Bill?
Are they even more sensitive to ignition timing inaccuracies than a parallel twin? If so why?
Sorry for the dumb question but your comment prodded my curiosity really hard with a very pointy stick.
-
'More so on a V' 'cos of the problem of demanding assymmetric operation of an instrument designed to work symmetrically.
My aside was a (too!) oblique reference to posts # 1852 & 1853 by wortluck and richard L on 10/09 under 'What have you done with your bike . . .' where there is a link to an excellent explanation by The Magneto Guys of the particular problems of V Twins, and a good review of how some makers developed workarounds. They're no more sensitive to all the camring stuff, but they start from a position of considerable weakness, and the weakness increases with the ° angle of the V.
A Thorspark conversion gets round pretty well all of the points of weakness, with what is basically a doubled-up version of their standard kit (you probably don't want a wasted spark on a V engine!) Adjustable for any V angle and can be grafted onto any magneto (as can all their kits in fact). Need a bit more current for the V version, as there are 2 triggers & coils etc, but still in the half-an-amp range; so within the limits of limited 'lectricks!
-
Thanks Bill, that makes sense now.
-
Have a Thorspark on my RGS lookalike as fitted by th PO.
Generally a 1st kick starter and runs well. Nice big blue spark. Running on 6v
-
Pazon also good, as with most e ignition some form of reminder to switch off is a very good idea, they don't like low battery voltage
-
Not A7 or A10 relevant but just as a matter of interest: My 1954 Mk2 Velocette LE is hand start and hand gear change and was almost impossible to start mainly because it wasn’t easy to get enough pull on the lever to turn the engine over fast enough. This clever electronic ignition solved it. It has two sensors on the controller board above and near the magnetic rotor, to trigger the sparks.
To make it easier to start hand start LEs it’s timed at the first sensor by turning the rotor, with either one of the pistons at tdc until the green led goes out, after the engine is running the second sensor takes over automatically and calculates the correct amount of advance needed thereafter. How clever is that!
The controller board and the two 3v coils are contained in the grey Miller generator cover seen at the front of the engine, which is nick named the biscuit tin. This is where the original coils, cb and atd was housed.
For the later kick start LEs only one sensor is needed and timed at the normal advance of tdc.
Minimag was designed and is manufactured by a clever Velo LE club member.
Rog.
-
Reading the LE experience, and other posts on electronic ignition, there appears to be a theme that (with designs that do away with the ATR) at a start up, the engine has to go through one cycle (one at least, and maybe two) of “triggering” of the spark, but that first “triggering” does not result in a spark - it just “callibrates” the ignition so it can then set the correct amount of retard, for starting at the next “triggering”. This is a problem points don’t have, as at low revs the ATR is retarded anyway. The electronic ignition needs to “see’ two triggerings to work out the engine is at low rpm and needs retarding to either avoid kick back (at starting) or pinking (if running at low revs).
I don’t profess to fully understand the technicalities of this, but surely if a (first, at least) “triggering” is effectively ignored surely this must result in either no start at first kick, or at least less chance? (and with a single, probably no chance).
Or is this just “urban myth”? That you can’t really have a “first kick start” with some electronic ignitions?
-
Or is this just “urban myth”? That you can’t really have a “first kick start” with some electronic ignitions?
Dunno KGF, but when I had Boyer systems on two bikes, sometimes they'd go first prod, other times not. Which doesn't help us! Battery voltage seemed to be the killer with them for me, as I just don't like leaving things on permanent trickle chargers in the shed. If I'm not in there, all power is OFF, too many rodents out my way!
The Minimag folk are very smart though - specialists in mini-systems as their name implies. See their site if interested: http://www.minimag.co/
On my own (kickstart & footchange) LE Velo I just use a double ended coil and standard points, wasted spark, and it's good. (The 3v Miller originals were cooked on mine, and far cheaper to substitute with a small Honda-style 6v double-ender.) When I had a hand-change one 50 years ago, the Miller coils still worked . . .
The Thorspark system retains the manual advance or ATD ('snot programmed in), see Question and Answer 6 here: http://www.sussexmotorcycles.com/thorspark-magneto-igniton-faq.html so the 'turn it over a time or two to set it' thing doesn't apply there at least.
-
... there appears to be a theme that (with designs that do away with the ATR) at a start up, the engine has to go through one cycle (one at least, and maybe two) of “triggering” of the spark, but that first “triggering” does not result in a spark - it just “callibrates” the ignition so it can then set the correct amount of retard, for starting at the next “triggering”. This is a problem points don’t have, as at low revs the ATR is retarded anyway. The electronic ignition needs to “see’ two triggerings to work out the engine is at low rpm and needs retarding to either avoid kick back (at starting) or pinking (if running at low revs).
Way back I built up a Triumph Daytona for my girlfriend to use. She had the most terrible job kick starting it, she was only a wee thing. To assist the process I fitted electronic ign. With that she couldn't start it all.
-
Originally I had a single sensor version fitted. Below is Julian Kemp's reply to me regarding my LEs difficult starting and also he recently told me that from now on double sensor versions will be supplied as standard to all hand start models.
Rog.
Thank you for bringing your starting issue to my attention.
It turns out some hand-start mechanisms don't impart a good spin on the crankshaft which can cause the starting difficulty you describe. It is exacerbated by the tightness of rebuilt engines, thick oil in cold weather etc.
The dual sensor, originally developed for BTH-PEC systems to make it easier to set up the ignition timing in such a confined space, has now been applied to the Miller controller.
The system locks timing at TDC for twenty revolutions and also disables coil power-down, thus the engine will fire if there is sufficient air-fuel mixture in the cylinders even at very slow or partial crankshaft rotation.
Please send in your controller and I will exchange it for a dual sensor version. There is no need to send anything else. You will need to reposition your timing rotor for the new controller. Instructions are supplied. Check you have the brass removal bolt. There is no charge for the dual sensor controller, just postage and packing.
This is happening because the engine is turning over so slowly and the coil time-out is operating. Energy already stored in the coils at this point will cause a spark at switch-off therefore it is timed at a safe point (BDC) to avoid a backfire. Advance is programmed to start at 1000RPM. You will not see it come on at starting speeds, even on a kickstart model.
Best regards,
Julian
Edit: I should explain that Advance referred to in Julian's last paragraph is the red led top right in photo. That was in reply to my statement to him that I've not seen the Advance led come on at all. I was checking with the engine at tickover and bike on its stand *doh*.
-
I think using the magneto bearings in paper cups and the mechanical auto advance, are two bad ideas in an electronic ignition.
I’ve been using the Wassell electronic ignition in a housing like this:
(https://th.bing.com/th/id/R.d0b46b318e3a906aa33da9aa998b2082?rik=avqVR7wKz%2fV8Lg&pid=ImgRaw&r=0)
It's in a low current draw mode when the engine isn’t running, but the bike (650 twin) usually starts first kick.
-
G'day Fellas.
I agree TT. Been using one like that on both my A's since the early 90's with Boyer. Very reliable and timing a breeze with a strobe.
Cheers
-
TT Back in the mists of time a cheap and reliable coil ignition alternative to the ageing K2F's was designed and manufacturer by Kirby Rowbotham, in Rugeley, Staffordshire UK.
This used a custom distributor housing, similar to yours, with contact points from the ever popular and available Ford Pinto OHC engine. The dizzy cap used was from a Fiat 500. The reasoning was that these other parts were freely available and of proven performance. Later versions evolved into the all singing and dancing electronic range we have now. After a long and successful association with the old bike movement, Kirby is now retired, by all accounts.
The USP of electronic ignition the Thorspark way is that there is no need for the additional expense of the modern housing, which alone represents a sizeable chunk of the cost to go electronic. Your old despised magneto does the job. Once fitted, (remember the magneto and its timing do not need to be disturbed) at first glance the machine looks to have its original magneto ignition. The magneto can be derelict inside, but as long as the armature turns the system will give consistent and reliable sparks. Poor magnetism, failed insulation, worn or non existent brushes, damaged slip rings, faulty coil and condenser are all of no consequence. All that is needed is a good set of bearings and an undamaged taper on the armature. It needs a battery powered supply, either from the machine or an external battery pack and power consumption is minimal. Available to suit 6 & 12 volt bikes.
The Thorspark system retains the mechanical advance system of the fitted magneto, and avoids the initial advance and starting problems of the more sophisticated electronic systems described above. It uses a wasted spark, so timing is identical on both cylinders, something not found on the majority of old worn maggys.
Swarfy.
-
Yup. To TT's and Musky's point, obviously a shorter and better-supported shaft without a whole lot of chunky redundant bits flying around between maggie bearings in paper insulators is better from the engineering point of view, but if looks and cost are part of the discussion, then to Swarfy's comments I reckon the Tspark thing is a decent option. I've seen a few high mileage Vincent twins do well on the (more expensive) doubled-up version , as well as some others on the simple £150 kit. The armatures seem to stay where they're meant to, anyway.
I'm biased like I said, and prefer to have mags where I can for all sorts of reasons, but the unit TT shows is nicely made. Probably nicer than the one here, which is from way back I assume.
It wouldn't be beyond the wit of an owner with some tools to replace the mag armature with a one piece tailor-made shaft and fit ball bearings when converting, but it'd be a bit over the top!
As far as the pros and cons of a programmed advance curve are concerned, I honestly dunno. On the 750 Notrun motor in my P11 I have noticed no performance downside from ditching the Boyer in favour of a mag (on which many Atlas engines run fine of course), and it's given the poor old alternator a bit more freedom to support higher wattage halogen lights. I didn't notice anything very obviously 'better' on the large Oilfield café-racer I had for years, on which I retained the BB system with its programmed advance - but maybe it was a tad smoother at low rpm & large throttle opening. Pretty marginal though, I'd say, though I never ran it with a mag to compare.
Horses for courses I guess, as ever.
-
Yes, the new housing adds £140 to the £85 for the Wassell electronics and about £30 for a dual coil.
Even more expense if you don’t already have a solid pinion and 12V electrics.
Every different approach has advantages, but that lot has been a good system with me.
I was happy with the magneto until all the new points sets fell to pieces.
-
A friend recently installed a Thorspark on his 500 Velo.. the electronic module keep touching the mag housing killing the ignition. He had to make up an insulating sleeve.
This magneto replacement housing on my A10 contains a Boyer Micro Power..The coil not fully concealed is just behind the steering neck. The bike has a 12 volt dynamo conversion that works just fine
-
My latest bike, a 1959 T110 has the Thor system installed. I rode the bike to a club night, during which I noted that the ammeter was not indicating a charge.I wasn't too fussed as I knew the battery was fully charged and that I would easily get home before flattening the battery. I should add that Ive done about 100 miles with no problems. On the way home, lights on, after riding about 2 miles, to say the engine back fired would be an understatement! The engine died immediately, needless to say in the middle of single lane roadworks. Once clear of traffic, I shoved it onto a side road and gave it a boot, upon which it started. Great, I'm on my way again. Well I was, until I turned the lights on. Another series of loud detonations ensued, so I gave up, called the breakdown truck and arrived home after midnight. My conclusion is that the Thor system needs a well charged battery in order to operate, although Thor say it will run all day on a run down battery. The bike also came with a Boyer Brandsen regulator which I ultimately discovered, only cuts in at high revs so I changed it for a DVR2 unit which supposedly cuts in at low revs. I've reset the timing using a strobe and will shortly be in a position to try it, but I'm now wary of being depedant upon the battery and charging system for forward motion, even if it does all work ok! Points, anyone?
-
I had an RE which came with Thorspark already fitted. All I can say is "it worked", but had I been the original owner I would have spent the money on a mag recon instead.
When you depend on generated power for your ignition (even the minute amount that Thorspark claim) you've lost that inherent get-you-home ability that a mag has.
-
Yes, I wouldn’t class the dynamo as a sufficient charging system for electronic ignition.
-
I did the 12 volt dynamo conversion with new bearings and new 12 volt armature, field coil and electronic regulator...With a 35 watt halogen H4 headlamp and Boyer ignition it's 14.2 volts at 2000 rpm....With battery alone and lights off, a little better than an hour to get home...Good enough for me... ;)
-
I think you'd have been Ok in daylight Zander, to be fair. But the load killed things well and truly.
I know people with various electronic systems running with dynamos, usually at 12v, and they seem to do OK as Trucked up says, but like TT, I've never thought it was a great idea in principle. The fine-wound '12v' armatures and fields are strictly limited to 60W or they'll likely throw the solder off the comm, so total continuous loads need to be well managed shall we say. You can actually get more out of the standard windings, subject to tolerating the higher cut-in speed required and using a decent regulator.
Were I to go there on a 'dynamo' bike I'd probably get an Alton I think if I was feeling rich enough, now that they have been improved quite a bit.
The bikes I've had electronic systems on have been alternator models - the Oilfield with a 200W job supported a 60 Watter - and Oxford 'Hot Hands' 'n all.
With a period Lucas job and zener and separate rectifier on the P11, a 60 Watter wasn't good at low revs with the earlier heavier-current-consuming BB system and an extra tooth here and there to gear her up a bit. A magneto plus an A Reg1 has transformed it. That bike is a '67, and it's obligatory to run with lights on all the time here in France post '65 . . . I didn't want just a glow-worm on what is (by the very limited standards of our old toys) almost a brisk machine. With not very good brakes by today's yardsticks!
-
I believe the thinner gauge wire armatures throwing soldier is also the quality of the piece ...Common sense says don't install 60 watt halogen bulbs along with electronic ignition...
-
Yep, it's all a bit of a compromise. I have new 12V field coil and armature on my A7 plus a DVR2 (not to be confused with the awful VReg2 thing) and it all works very well, though I'm still running an over-hauled Lucas mag.
No fancy Halogen or LEDs required.
-
Thanks Swarfy. Those are all the reasons I liked the sound of Thorspark. The potential downside is reliance on a battery. Have you run a bike of your own with Thorspark?