Author Topic: Thorspark any good?  (Read 516 times)

Offline Ewen

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Thorspark any good?
« 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.

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Re: Thorspark any good?
« Reply #1 on: 14.09. 2021 21:22 »
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!
Bill

Offline Minto

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Re: Thorspark any good?
« Reply #2 on: 15.09. 2021 01:32 »
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.
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Re: Thorspark any good?
« Reply #3 on: 15.09. 2021 07:08 »
'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!

 
Bill

Offline Minto

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Re: Thorspark any good?
« Reply #4 on: 16.09. 2021 01:03 »
Thanks Bill, that makes sense now.
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Offline Gearbox

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Re: Thorspark any good?
« Reply #5 on: 16.09. 2021 08:06 »
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

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Online bsa-bill

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Re: Thorspark any good?
« Reply #6 on: 16.09. 2021 11:41 »
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
All the best - Bill
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Offline RogerSB

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Re: Thorspark any good?
« Reply #7 on: 16.09. 2021 11:52 »
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.

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Re: Thorspark any good?
« Reply #8 on: 16.09. 2021 12:17 »
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?
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Re: Thorspark any good?
« Reply #9 on: 16.09. 2021 13:38 »
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.
Bill

Offline Butch (cb)

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Re: Thorspark any good?
« Reply #10 on: 16.09. 2021 14:15 »
... 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.
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Offline RogerSB

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Re: Thorspark any good?
« Reply #11 on: 16.09. 2021 14:36 »
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*

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Re: Thorspark any good?
« Reply #12 on: 16.09. 2021 19:04 »
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:



It's in a low current draw mode when the engine isn’t running, but the bike (650 twin) usually starts first kick.

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Re: Thorspark any good?
« Reply #13 on: 16.09. 2021 21:05 »
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.
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Offline Swarfcut

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Re: Thorspark any good?
« Reply #14 on: 17.09. 2021 08:13 »
 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.