ET: Engine (Twin) Seeking Ignition Suggestions For Twin - Can't Get The ATD Fitted

[CarlHungness]

I am so knackered in trying to fit my ATD to my newly rebuilt Lucas mag I'm looking for suggestions for alternatives. A new ATD is $345 US dollars plus postage and I've already spent $400 on the magneto that I'm ready to throw in the towel. I sure loved my old B-TH that worked a treat for 20 years, but it SEEMS to have given up the ghost, and I've spent another $100 US on it for new (factory) coils and some aftermarket ones as well. B-TH isn't real interested in looking at a 20 year old mag and I've heard some iffy stories about the new ones (surging) so may have to bite the bullet and go with a battery ignition, which really goes against my grain.

 

[CarlHungness]

Has anyone used the Thorspark from Sussex Motorcycles

 

[Simon Dinsdale]

Has anyone used the Thorspark from Sussex Motorcycles

Thorspark I believe just replaces the mag points with an electronic pickup which operates a separate ignition coil. The magneto is still used as a mechanical rotating shaft but doesn’t generate its own spark. So the ATD is still used and if you have a problem seating the ATD then that problem will still be there.

 

[Shane998]

I am so knackered in trying to fit my ATD to my newly rebuilt Lucas mag I'm looking for suggestions for alternatives. A new ATD is $345 US dollars plus postage and I've already spent $400 on the magneto that I'm ready to throw in the towel. I sure loved my old B-TH that worked a treat for 20 years, but it SEEMS to have given up the ghost, and I've spent another $100 US on it for new (factory) coils and some aftermarket ones as well. B-TH isn't real interested in looking at a 20 year old mag and I've heard some iffy stories about the new ones (surging) so may have to bite the bullet and go with a battery ignition, which really goes against my grain.

Having spent the money rebuilding magneto I r would try a new ATD Talk to the supplier /manufacturer the new ones I have have slightly longer arms that the springs attach and are an improvement. Maybe if you discuss your problems with the supplier / manufacturer he could give an opinion

 

[lee_812d]

Are the threads on the current ATD damaged or is it just difficult to set in the right place? If the ATD you have isn't broken and has the correct range then it would be annoying to replace it for no reason.
I suppose there is the option to replace the ATD with a manual unit but that will cost money as well, and could be awkward to fit as well.

 

[Peter Holmes]

If you have a surplus ATD with a good taper and Tufnol gear, but the mechanism itself is worn beyond acceptable limits, you could tack weld the central moving boss to the outer ears, and use the BT-H ignition device which has a built in advance curve, but you would still be reliant on a good taper fit, I am not sure that lapping with grinding paste is the best engineering solution, although I have done this myself, but you are only matching two components at the time of lapping, plus you are removing metal, and therefore moving the ATD gear inward a little the more you lap, not such a problem with the ATD taper, but maybe a problem down the line with the ignition device taper.

But having followed your trials and tribulations, I think the problem must lie with ignition timing slippage, nothing else makes any sense, if it were a cam turning on the camshaft, it would seem most unlikely that this could occur to both cams simultaneously, and a Vincent twin engine will start and run on one cylinder, although your right leg will know all about it. You seem to have ruled out all fuel problems.

Good Luck

Peter

 

[Keith Martin]

Which gasket are you using on the magneto mounting base? I have seen the grey gaskets supplied by Coventry and the Cometic ones that are to thick. This will move the ATD in too close to the case causing it to rub on the case. We always use the thin paper ones.

 

[vibrac]

I am in the UK just 15 miles from B-TH man I have not heard that he wont recondition a mag he certainly did mine about 3 years ago after a decade on the race track its now on my road Comet worth asking the head office...

Contact Us

Contact Us

www.bt-h.biz

 

[b'knighted]

Has anyone used the Thorspark from Sussex Motorcycles

Yes, it works well to add coil ignition to a defunct mag but it won’t help you as it still uses the mag, minus cam & points setup, and is driven and advanced by the ATD.

 

[Cyborg]

Which gasket are you using on the magneto mounting base? I have seen the grey gaskets supplied by Coventry and the Cometic ones that are to thick. This will move the ATD in too close to the case causing it to rub on the case. We always use the thin paper ones.

Glad you mentioned that. I have never used one before, but I have a brand new Cometic gasket hanging on the cases waiting for me to finish the mag. I’m using a slack wire advance setup with the Lightning style gear/tach drive etc, so maybe not an issue in my situation, but definitely worth checking. I could see that driving someone nuts trying to deal with the bolt on the ATD. Might explain the difficulties with that horseshoe washer.