Electra nearly there.

However, as it would be wired in using existing bullet connectors, it would be the work of a moment to disconnect and reinstate as original. I'm not convinced I need it but may just try out of interest.

Push start? Beyond me I think. But you're right the kickstart is there and the engine starts fairly easily using it. The scenario that worries me - and why I replaced my ES2 with the Electra in the first place - is stalling the engine in traffic and being unable to restart while astride.

... this morning so it was an easy fitment. It does indeed step up (or down) the voltage it receives. However, it seems to do this in a fixed ratio with the input so as the input voltage drops so does what's available, so no advantage. But for a fiver I've learned something.

I suppose what I could do if I was minded would be to put a changeover relay so that in normal running the Boyer etc are fed direct but when starting they could be fed from this device. But that does seem like overkill.

I do think it was worth a try. I have also discovered that the battery needs to be pretty much fully charged otherwise cranking voltage drops below 10.

The clatter on Lightweight Twins generaly comes from the cam followers, as you correctly imagine. The cam lifts them off-centre, with idea being that they will rotate to even out wear. The reality is that over time, the stem wears into a barrel shape - little wear in the centre, but well worn at top and bottom of travel.

There is little you can do about this - but you need to keep an eye on this, as the wobble introduced by extreme wear will affect the cam follower face, where it meets the cam, and will also damage your cams.

Its one of the things you need to check on high mileage engines - or if the clattering is excessive

Yes, I've noticed that it sometimes fires on releasing the button. If I could time this correctly..... Ambient temperature seems to have a lot of influence - last week in the warm weather it was starting reliably, this week as it's colder it's struggling a bit. But being a fair weather rider these days I don't think it'll be an issue.

I seem to remember from my long ago days as an AA patrol that it was Ford that first used the ballast resistor, and as you say my 850 Commando had one as it had 6 volt coils. But of course it was in circuit all the time.

The rattle isn't too loud although don't have any reference point so think I'll leave well(?) alone.

... which I would have thought enough. It spins the engine over very happily. As a matter of interest I've just popped the plugs out and they were black so cleaned them with a bit of carb cleaner and the engine started on the first push. Fully charged battery however.

This site has some interesting stuff about battery CCA etc. An interesting table showing how available power drops off with temperature - and how CCA is measured. Temperature has a far bigger effect than I had realised. But as I say, we FWBs don't care!

 is  aYB9-AGM Powerline again from Tayna. It should be enough at 120 CCA and 9Ah.

https://www.tayna.co.uk/motorcycle-batteries/powerline/yb9-b-agm/

I'd be interested if anybody could tell me what voltage they get when the engine is cranking. With a charged battery I'm getting around 10.4 volts. Voltage at rest is 12.7.

.. as though they will work well Nick.

... is now starting immediately the button is pressed (without the fancy voltage controller). I put it down to warmer weather and a fully charged battery.

I have to say I forsook it this afternoon for a shakedown pre-MoT and pre-sale run on my little Yamaha V-twin. A very pleasant ride but am looking forward to getting on the Norton!

... but initial rides will just be up & down my local lane (Icknield Street) so it isn't too far to push home.

On the meantime here are my 3 bikes while all present and correct.

... it's fitted with an ex-CCM Suzuki DRZ400 engine by a previous owner. A nice engineering job with even gearchange and rear brake on the proper sides although I needed to change the former to one up four down to work in correct (ie Norton) pattern. It also needed a lot of minor but important tweaking. I've only ridden it once - couldn't get on with the Triumph gearchange pattern - but it went very well.

... so pushed the little Norton out of the garage into the sunlight, started it up (first push of the button) and wobbled off for a very short - 2 miles or so - ride backwards and forwards along the local lane.

Good points:
Excellent riding position, good brakes, lovely planted feel. Plenty of urge - pulled up a hill - maybe 1 in 10 - in top with no trouble. Decent gearchange although there was too much slack in the clutch cable so neutral was somewhat elusive. It's a much nicer ride than the Yam, to my relief.

Bad points:
Only one really. It doesn't like to restart after the first try. I managed to stall it when trying to set off and it took several goes to get it running again. The same when I deliberately stopped the engine half way through my little run. I suspect the plugs (Champion N4C) may be on the hard side? And I've only been able to adjust the mixture when it's been cold so that needs some attention. The problem is that having had one hip and one knee replaced, I find getting my foot up far enough to use the kickstart almost impossible. Hence my choice of the Electra.

So I'm feeling much more confident about taking it for a longer run as long as I don't have to stop the engine!

... shows a nice colour although interestingly not wet at all. I'm still wondering whether there's enough voltage to trigger the Boyer properly although this may be leading me along the primrose path. I'm also tempted to try a couple of NGK (B6ES?) plugs or maybe even posh platinum ones. There do seem to be plenty of sparks at the plug when spun over.

..When I rewired the bike I used very heavy duty (10 sq mm) cables for the main earth and starter / solenoid connections, reasoning that this would minimise voltage loss and give the starter motor the best chance of operating. This has proved very successful in that respect. However, I am led to wonder whether the large current draw from the battery which this allows may drop the available voltage at the Boyer below its minimum level. Maybe this is why it start instantly with a fully charged battery, but on subsequent attempts the battery voltage will have dropped - maybe by just enough?

I plan to try connecting in an external battery to the Boyer so that it's getting its full whack. Not viable for actual riding but may lead me to revisiting my voltage controller idea with relay control.

Boyer say that the version I have ( a new one, Mk 4) works down to 7.5 volts. I did try what I outlined with an auxiliary battery and it seemed to make some improvement.

However - I have discovered that I can get an almost reliable start by only letting the starter operate for a couple of revolutions then releasing the button. I've been letting it churn over for several seconds. So maybe the problem all along has been my technique. Give me an ES2 with a valve lifter and I know exactly what to do!

... not sure what plugs to try. Any recommendations? Once started, the engine runs very well.