Twin sparking a single cylinder. Plug gaps and caps?

[WD Forte]

OK mad idea 2
You see the first gear after the crank with a hole in it?
(Assuming it runs at half crank speed)
A sensor mounted on the cover with an IR opto or hall effect device could sense the absence of material
response to trigger an ignition event with far less back lash.

If the gear (the exhaust valve cam I assume?) is keyed then that would help fix the position of a sensor
otherwise it would need to be determined so if it was ever removed, refitted in the exactly the same position.

I'll also assume that others have had their own solutions to this and not sure how good or feckin expensive
they are.
____________________
bikers smell of wee

[lingeringstin...]

Ah, I see the problem with the Wipac-style thingy being rather small and there not being enough room to faff about in there.

My simple cheapo Chinese rotor with an external AC CDI works great. You can literally start the bike by cranking the rotor bolt by hand with a socket if you feel like it and it will push start easily without even a battery. But it takes up space that you don't have. A conundrum indeed.

Any chance of running a dry clutch and fabricating or modifying a cover to take the GY6 rotor gubbins?

[lingeringstin...]

Hang on, does one even NEED a cover there? Why not just get jiggy with shaft seals and run an open primary kind of thing? Yes it would look retarded but it would free up some space for alternator shenanigans.

I once ruined one of my experimental engines by forgetting to put oil in it when I fitted it to the bike and after a couple of days the con rods started to knock. Once I realised that I'd neglected to put oil in the damned thing I took the engine off and stripped it down to see what the damages were. The crank and cam had gone to pot but the clutch and gearbox seemed not to have suffered any damage at all. I had been running a dry clutch all that time and it just worked fine. Made me wonder why the clutch was designed to exist in an oil bath anyway. It didn't seem bothered by running dry.

Of course I have no experience with Enfields so it's just a thought.



MEANWHILE, THE NEXT MORNING IN THE GARAGE...

Sips coffee. Remembers looking at that Enfield pic of the vaguely Wipac looking air gapped alternator. Remembers when I cobbled one of those onto my MZ engine. Worked pretty well actually. Don't know why people hate them so much...

Sips coffee. Thinks about that picture of the Enfield clutch with the chain etc. Never had one like that myself but as I recall they use a different grade of oil in there to what's in the engine. ATF or something generally gets recommended I think. Hmmm.

WAIT A MINUTE- (spits out coffee)

How the feck does an air gapped alternator live in the same case as an oil bath clutch? Bloody Hell. I really need to pay more attention to things before chucking my theories into the fray.

Please disregard that erroneous tale of ruining a brand new engine rebuild by forgetting to put oil in it. Nobody would ever do such a thing. Especially me.

Looks at pile of engine bits in the corner.

SHUT UP YOU. THIS IS JUST OUR DIRTY SECRET.

Now my coffee's cold. Feck.

[WD Forte]

A lot of bike alternators live in an oily chamber
I did wonder about Stinkers RE setup myself but looking at the primary chain I reckoned/assumed it needed lube in real ife and the pic we see
is a nice clean 'during assembly' pic.
Mind you, waddooino? maybe it does run dry.
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bikers smell of wee

[stinkwheel]

Yes, it's normally sat in oil. I use ATF, others just use engine oil. You can run it dry if you do a belt primary drive conversion but that clutch. was £££ so it's staying!

I hadn't thought of triggering an ignition pulse off the cam sprocket. There is minimal backlash there because they are more precisely machined than the idler gears. I think the oil pump assembly might be in the way of anywhere you could put a sensor though (it's in the timing chest cover, driven off the end of the crank). I'll have a good look at it.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[stinkwheel]

I've got a twin coil/plug setup fitted.

I went with a set of aftermarket japanese coils designed for a 1970s GN 250 (basic points ignition bike). They were listed as 6ohm but actually turned out to be around 4 ohm like all the other ones.

I've rigged them connected in parallel to a plate under the seat, I have a condenser seperately mounted in paralell to each one and have removed the stock condenser.

This produced a good spark at each plug but it draws 7A under normal running conditions which is a bit much for my liking and is likely to cook the points quick-sharp.

Doesn't look like you can readily get ignition coils with much more than a 4 ohm primary winging which would be ideal So it ocurred to me that one way to drop the current load is to add a ballast resistor in series with them. This is a double-edged sword because it also drops the voltage at the coils.

I've set it up with a 1.6 ohm ceramic ballast, mainly because this is the standard one used on vintage car and agricultural implement ignitions so you can fairly reliably source a good quality replacement if it fails, agricultural merchants usually stock them.

This setup drops the current draw (at 14V) to 3.89A which is much closer to the stock setup. However it does drop the coil voltage to 7.8V. The big question is, is this enough voltage for reliable sparking?

A brief road test saw the bike fire up as easily as it ever has and pulling well up to high revs. Plugs seem clean. I will do a longer road test tomorrow when my wife is home so there's a recovery service available if it all goes wrong.

https://lh3.googleusercontent.com/pw/AP1GczOBhdZWJoLqCkDjhavVVPXOpfTodMCP8wYefDj-2-oe2jieZJ9xZMSxB6SgejeoKUOgcAjIfH0F8dVjpQCdSfKYKr_usMSyAW2Qbrh1J7iEIA2_oHOPJkJ2x2t9f9I7fZIYmLS1sLFw9zXYsSGR-0-aIQ=w937-h785-s-no

There is leeway to fiddle with the ballast, it's a payoff between current and voltage at the coils. If I dropped the ballast to 0.7 ohm, I'd be drawing 5.19A and seeing 10.4V at the coils.

With hindsight, I should have gone for a pair of 6V coils (I believe Norton did this). They tend to be 2.5 ohm. A pair of 2.5 ohm coils in parallel with a 1.6 ohm ballast in series with them would give me a draw of 4.9A and 6.1V at each coil. Upping the ballast to 2 ohm would give a points-friendly 4.3A and 5.4V at the coils.

If this all goes haywire (like with a charging system failure), I can fairly easily just disconnect the ballast and one of the coils which would put things back to a standard single plug setup.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[stinkwheel]

https://lh3.googleusercontent.com/pw/AP1GczNfL5OURvBfBJdauaNUPFKqISq9FkLMPZT-sbOjZPyzy8gMoLrs-TGNVpZgxntwQKN8VOKTKsCZaoh7iVhl4QVOOdCVhoIkRzySG-O1SvX_EQ1YjsfmI5l5wjYX2gQZK55VdHx1O3UZM49fGu7u59wy7w=w1669-h939-s-no

https://lh3.googleusercontent.com/pw/AP1GczOXH-4CQ4kKXplmoHH7VKcKtRA5VNOj--i_o_hKrXKXtC-L6kwTEvxaaa3i6Se4YVu4bRT9pbDtVECDXi9IB22AiWp4NREvjqFILoJvZ2vXKjGsT4UFcJjtuTsANuIW9t9jD3rPBMAEFw9Emyil9tkVhg=w1669-h939-s-no

https://lh3.googleusercontent.com/pw/AP1GczO-LpY0S799IVFC2oeLMylNtxz8ZdwDJj7OIPBHNK489DuzhgTT0NXu6ca5BqStWfsbKDr1ZGzSdTBs_VF-JVKIrBd30nouvN5K2bTbv8z2gQbXgA3rMqmdQufV1OLaWcgIkMHjFdqW85uhC-ffRegVRw=w1669-h939-s-no
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.