I know there's no success like failure....

Of course I had to strip the primary drive to fix the loose inner primary chaincase so it was an opportune point to fit the bigger sprocket which I'd already ordered - following Peter's and Andy's comments I think - in advance. It's brisk enough off the mark but to me 70 feels as though it may struggle to reach although I weigh well over 100kg kitted up so that won't help.

I'm not sure of the accuracy of the speedo and if I find time may pop out this afternoon and use a GPS app on my phone to check it.

I think I have some EP90 in the garage so will think about a change. I remember that the late lamented Fred Barlow always recommended 140 grade gear oil in the Commando and that worked very well.

... the charging system seems in excellent health and the split charge arrangement is working - the auxiliary battery is well charged as well as the main one. I was just wondering whether I should see the constant 4 -5 amps when all is charged but I suppose it's just warming the Zener diode up!

... why the current going through the Zener shouldn't be shown. My setup - which may of course be wrong - has the ammeter between the battery live lead (brown / blue) and the rectified alternator output (and load) (brown / white) so will show anything being dumped by the zener. It's consistent with the Lucas diagrams on p84 of the book "Wiring diagrams for AC motorcycles". I have completely ditched the original wipac wiring and am using a version of that Lucas layout.

Voltage across the battery at say 3,000 rpm is of the order of 14.5 volts ie what I would expect after clipping by the zener.

... I think you're right. But I think that's how I've wired it. I must go and check as my mind is getting blown more often than the fuses. 

... I think I have it right. I assume the 4 amps or so is just keeping the battery(s) charged. See sketch below.

... it just stops dead. But remember the ignition circuit is powered from the auxiliary battery which is switched in by a relay from the ignition switch. So there is no direct connection from the charging side to the ignition circuit other than via the voltage sensitive relay.

 but it shows about 4 amps discharge with the headlight on and engine not running. Of course this doesn't include the ignition. Looks about right to me. I'm not actually bothered about the 4 amp charge which is around 48 watts or so so probably is being correctly limited by the Zener.

from Hitchcock on Wednesday and it arrived in the post on Thursday morning. Excellent service. Now fitted and it will make it easier to change on the fly. I assume Michael's photo is intended to show the friction adjuster on the twistgrip which I admit I rarely use these days having indicators on my bikes but I may think about it.

I'm also considering fitting a large thumbwheel on the extended throttle stop or even fashioning something like the fast idle stop on the pre-unit Amals fitted to old singles. I made something like this for the monobloc on my ES2.

... I decided to make a throttle stop similar in principle to the one illustrated. The extended one supplied by Hitchcock's was OK but lacked any way to return to a fixed (warm idle) position. Rummaging around in the scrap bin I found a length of phosphor bronze and a Schrader valve adaptor for Presto tyres as well as some 2mm aluminium sheet. I have a box full of discarded Amal carbs and parts which provided a throttle stop screw.

First I bored the outer end of the throttle stop screw with a 3mm drill. I then made a double diameter adaptor - one end went in the bored hole, the other fitted inside the Schrader adaptor. I then soft soldered it all together. I made a stop / pointer out of the alloy sheet and secured it to the adaptor with a valve stem securing nut. I should tidy up the adges of the stop/pointer and remove my marking out line!

This arrangement seems to work very well although have only tested it in the garage so have guessed at the warm idle setting Half a turn makes a significant difference in engine speed.

... with a warm engine as it should be then it's too slow when it's cold and the engine will just stop eg when left on the prop stand while I put my helmet and gloves on or at one of the many traffic stops I encounter in the first couple of miles from home. If idle speed is set higher to counter this then it's too fast when warm. The extended screw from Amal addresses this to some extent but requires very precise operation - not always easy as a quarter turn on the screw goes from slow idle to racing.

My device allows normal idle speed to be set precisely - the cold starting position is less critical and depends to some extent on ambient temperature. Many carburettors other than slide types have some sort of arrangement to increase idle speed on a cold engine.

This kind of device was standard on Norton and Velocette singles just post-war and I don't think it would have been offered unless riders found it useful. It was known as the easy starting stop and is described in Edgar Franks's book.

having been riding for 60 years I think I know how to do it by now. However, I hate people sitting at traffic lights blipping the throttle unless of course they have a GP carb. I've always striven for a nice even tickover. Witness my ES2.

https://youtu.be/y6IMRXgZE8k?si=Ih5CzNHsmhGSgopV

Peter: of course the Concentric clone has an "enrichment device" otherwise known as an air lever. However, once started this is raised to a greater or lesser degree hence has no effect at tickover. Inevitably that tickover speed is lower with a cold or cool engine.

Whatever others think I find this sort of thing useful as did pre- and post-war Norton and Velo owners. If you don't like it that's fine. I posted in the probably incorrect belief that others may have been interested.
 

Yes.

https://youtu.be/31FqpkF2PK0?si=paVNxG_74UdIDlgn

But not with the hand change Sunbeam, which is another bike you had to walk to the back to get it off the stand.....

https://youtu.be/nXeHqpRBJ1s?si=D8EMJa3q8tVac3QT

Re hand throttle: the Series 3 Land Rover I drove as an AA patrol in the early 1970s had one. Quite useful it was too. The Land Rover had a mechanical governor which hunted when idling in a quite pleasing manner.