the engine dying issue with electronic ignition is a common symptom of a loose wire, particularly the ignition earth wire which i would check first, 12 volt feed to igniton and pick up wires are all suspects.
any swarth on top of thee piston will most likely pass through the exhaust valve into the exhaust.

i have had a similar problem on my thunderbolt with a new wassel carb.
choke and tick over o k ish but jerky pulling away unless choke on. i raised the needle 2 notches from standard settings but now a lot better.

i ve read synthetic oil is the best form of oil protection on running surfaces but the customer is always right. in my experience if straight oils do not get hot enough it caN build up sludge in the bottom of the oil tank.

i think bsa recommended sae 40 mono in the summer [a10 handbook ] but a worn engine would benefit from a straight 50 when hot.
just substitute sae 40 with sae 50 and use the owners handbook =summer which is about now until it gets cold around october.

i wonder if anyone can help identifying my 1971 a65 crankcase threads i need to block. it is the 2 oil gallery holes bellow the oil pump and prv that are normally blocked off. the screws are missing [ probably drilled out ] and the threads are fine, similar to the oil pressure switch thread.
some information i ve read refers to 1/8 nps or 1/8 asp for the oil switch.

hi allan
yes your right, a good magnetic speedo can be very accurate if you can find one. i have a mixed lot of u/s and 2 that have opposite rotation and work with a drill holding the cable but not when connected to the speedo drive. it was causing a lot of frustration. the new emigo speedo i fitted is not as accurate with a 2/1 drive as you would expect a chronometric speedo to be. mine over reads mph a tiny amount but is close enough when the other option is a shagged smiths magnetic one. i would be interested to know the current price of a magnetic speedo rebuild is ,compared to the £80 i paid for the emigo unit.

1600 seems to be a more general ratio that would take into account various factors such as 18 or 19 " driven wheels and probably still over read slightly. for accuracy similar to gps a chronometric speedo of the 1575 type would be the way to go IMO. but they are bloody dear if you can find one. i think mines of a ajs 650.

well,
i fitted the 2/1 speedo drive and is accurate enough to assert that the speedo head must be near a 1600 rpm unit.
bob , i would say your speedo expert mate was spot on and the slight difference of 1.9 / 1 allows the speedo head to slightly over read and therefore remain legal as its unlawful to under read.
i dont feel the emigo drive unit to be as well built as a original smiths and the unit goes a little stiff when the spindle is tight so i guess it needs a thin washer in there to stop distortion.
i dont think the speedo cable i bought is as good as the original either except the square dive on the original has worn about 0.5 mm.
finally i m riding legally with a working speedo , so thanks for all the comments. however i have a 1575 chronometric speedo head on my a10 which has spot on accuracy and maybe i should have gone that route.

hi allen
its an emigo speedo with no ratio given that i can see.

sounds like the same issue norton owners have with the 3 to 6 start oil drive pinion off the crankshaft.
some of those owners use a adjuster in the feed pipe to the rockers to find the optimum oil supply without smoking and leaks.

i may be able to turn up at the birmingham camping weekend on the saturday and camp overnight.
do i have to buy a ticket in advance or can i just turn up ?

i ve seen a video of the triumph factory using wellseal to seal the crankcases and other engine parts.
i have some old a10 crankcases and i think bsa used hermatite red.

hi cornish bob
i followed up from your reply and ordered a 2/1 speedo drive from a different supplier than where i bought the speedo and drive.
i was a little disappointed with them as they promised back up when i bought the items not knowing if the ratios would work .
i emailed the online shop but had no answer.
I will let you know the result and accuracy when i fit the 2/1 drive.

hello
i have bought an emigo speedo which works great but over reads by about a third. i m wondering if the speedo is  a 1600 ratio instead of a 1000 ratio. the speedo drive is 1.25 / 1 and i am asking any knowledgeable person on the forum whether a 2/1 ratio speedo drive would be the way forward.

i tried extended nose spark plugs in my youth and they made my a10 sound like an unsilenced tractor but went really well. almost like a racer. classic race bikes probably use them but it was the noise that put me off. if your head has leaky guides i ve read they are less likely to oil up due to being away from any surface where the oil runs.