The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: UncleD on 24.03. 2019 07:19

Title: Electric ignition and mag driven tacho
Post by: UncleD on 24.03. 2019 07:19
I have a 58 SR that has the mag driven tacho but has had a later model K2F with ATD...so not compatible.  At present the tacho is in place but disconnected (I cut the drive paddle off the back of the tractor tacho drive that was in place)!

I am having all sorts of difficulty with the points gap (wildly out of balance) and therefore poor timing & running.  The ramps on the cam ring were different heights (3.54mm and 3.64mm) but even after gently grinding them to be equal, the points gap difference is still out (.012 and .019) so I suspect that the housing is also out of shape...or something!

I am coming to the opinion that electronic ignition is the way to go rather than spend money on this incorrect K2F or try to buy a refurbished manual version.  I have EI on my A65T so not spooked by the mysterious black box.  I know I need to upgrade to 12V and can do the research on the brand of EI (although happy to take suggestions).

My question is...can the tacho be driven from the back of the mag with electronic ignition in place?  I am assuming it will run off the pinion bolt just like the original manual magneto would have.  Does the fibre pinion remain in place or is it replaced with a solid one?

Title: Re: Electric ignition and mag driven tacho
Post by: Swarfcut on 24.03. 2019 08:20
G'Day UncleD.
    There are several factors worth considering, the major one for most people is cost. Replacing the magneto as a carrier for the system adds considerably to the outlay.

   Provided the magneto is in reasonable order, my choice is Thorspark, which retains the magneto and existing ATD, simply substituting the contact breaker points plate for the electronic trigger. This fits entirely inside the end cap. This output is fed to a twin lead coil, firing both plugs at the same time, avoiding the imbalance you have with the pesky cam ring. It is available in either 6volt and 12volt versions, easily fitted and can be removed without any alteration to the magneto. For comparison, in the UK today it is priced at £150, plus a quoted £17.50 for postage outside Europe. They may have agents in OZ.

 The exiting Tacho set up will work as it is driven as before, theoretically the extra drag on an ATD may alter the timing at low speeds, until full advance is achieved, which is why standard set up was  magneto drive, with solid cam wheel and manual advance.

 Pazon and Boyer systems are widely available for later points/coil type  systems, as on your A65, but when it comes to magneto systems these types generally require a new housing, which adds to the cost. However, these systems have electronic advance and a solid drive gear which is easily adapted to drive the Tacho gearbox.

 If you win the Lottery, "Lucas" now market an electronic look alike magneto, as a further possible choice.

 Be interesting to see what other Fellow Sufferers recommend.

 Keep Spannering

 Swarfy.

 Additional.. Add Tri-Spark to possible choices.. Thanks Pete.

 
Title: Re: Electric ignition and mag driven tacho
Post by: Peter in Aus on 24.03. 2019 08:58
I sold my magneto which nearly covered the cost of the Tri-Spark kit from South Australia *smiley4* best way to go if you are not a purist and just want to ride your bike!
Peter
Title: Re: Electric ignition and mag driven tacho
Post by: Triton Thrasher on 24.03. 2019 09:00
An electronic ignition that uses the centrifugal ATD and tufnol gear sounds daft to me.

You are right to not drive a tachometer with the auto-advance.

I think a Wassell electronic ignition and housing was about £240 in total. I already had a coil.
Title: Re: Electric ignition and mag driven tacho
Post by: KiwiGF on 24.03. 2019 10:48
I have a 58 SR that has the mag driven tacho but has had a later model K2F with ATD...so not compatible.  At present the tacho is in place but disconnected (I cut the drive paddle off the back of the tractor tacho drive that was in place)!

I am having all sorts of difficulty with the points gap (wildly out of balance) and therefore poor timing & running.  The ramps on the cam ring were different heights (3.54mm and 3.64mm) but even after gently grinding them to be equal, the points gap difference is still out (.012 and .019) so I suspect that the housing is also out of shape...or something!

I am coming to the opinion that electronic ignition is the way to go rather than spend money on this incorrect K2F or try to buy a refurbished manual version.  I have EI on my A65T so not spooked by the mysterious black box.  I know I need to upgrade to 12V and can do the research on the brand of EI (although happy to take suggestions).

My question is...can the tacho be driven from the back of the mag with electronic ignition in place?  I am assuming it will run off the pinion bolt just like the original manual magneto would have.  Does the fibre pinion remain in place or is it replaced with a solid one?

I’ve got a BTH electronic mag driven by solid alloy gear as it has built in advance, they cost a fortune but would work a  Tacho? The BTH I have (its a few years old and has been superseded) does not require power so you could avoid a 12v conversion.
Title: Re: Electric ignition and mag driven tacho
Post by: muskrat on 24.03. 2019 19:15
G'day UncleD.
I have Boyer in both mine.
https://www.a7a10.net/forum/index.php?topic=12198.0
https://www.a7a10.net/forum/index.php?topic=8219.0
Just did a quick search. About $600 for the housing, ignition, coils, alloy pinion & tacho drive nut. Then the DVR2 reg to convert to 12v $110. 12v battery and globes $80.
Then you may need a dynamo freshen up and belt drive kit add another $2-300.
I luv mine till the sparkles dry up, then I wish for a magy.
Cheers
Title: Re: Electric ignition and mag driven tacho
Post by: chaterlea25 on 24.03. 2019 20:50
Hi All,
Unlike a lot of the Wassel items the electronic ignition is a very good product
The units are made by what was the PAL magneto factory (Former employees) in the Czech Republic

John
Title: Re: Electric ignition and mag driven tacho
Post by: KiwiGF on 25.03. 2019 01:12
https://www.bt-h.biz/k2f--lucas-replica-flange-magneto-13-p.asp

£774 nowadays for the ktf.....ouch

Title: Re: Electric ignition and mag driven tacho
Post by: Swarfcut on 25.03. 2019 07:16
KiWi.. Just read the copy...."For the owner who wants to preserve the original appearance" Reduce inheritance tax or the kid's legacy, morelike. As I said, if you win the lottery........ Ouch Indeed!

 Swarfy.
Title: Re: Electric ignition and mag driven tacho
Post by: UncleD on 25.03. 2019 10:40
G'day all, Mr Pendulum here on the other side of the fulcrum.

Got a quote to refurbish my K2F and convert to a manual A/R...worst case scenario (replace everything...bearings, cam ring etc) is $750...plus $100 for solid pinion & nut (hope to recoup something from the ATD).

Although EI varies in form and price, once I've done everything Musky mentions, I'm about in the same ball park (give or take a hundred)...so dammit, I'm staying maggy.  Closer to original, natural connection to tacho drive and unique.

...until tomorrow...