Dear Mikaw,
I more or less did as you have listed:
Checked switch operates as per the bike's manual and wire colours all correct. Zero resistance across switched contacts.
I then ran 12 volt through the switched wires to a headlight bulb and checked no voltage drop. To load test them.
Made up short insulated connectors of greater cross sectional area so as not to introduce added resistance.
With their bladed ends pushed into the spades on the out going female plug leaving the switch cable and thus the switch completely disconnected. So bypassed.
Took out every female connector individually from the plug body and re-tensioned them whilst doing this.
Rode 20 miles with the switch bypassed. - Same poor running problem "around town". OK cruising.
The hot wire idea is certainly worth a try, thanks, as it will eliminate a lot of the basic wiring and the switch from the situation.
It was badly missing on one cylinder when started from cold today and took a good while to pick up properly. This problem has crept in, in the last couple of days.
This will give me something to get my teeth into tomorrow when I run it with the tank off and identify which pot is playing up.
The bike in the last year has had a rebore with new pistons, the valves cut in and re-shimmed, new sliders and diaphragms in the carbs, new OEM air filter, new main and pilot jets, new inlet hoses and new hoses from the air box to the carbs, new plugs, new high tension leads, one coil replaced. The list gets longer if I turn to stuff other than the engine. I feel pretty sure the carburation is right now. Tomorrow will tell.
No one has come forward so far with a suggestion of where to try to get a new switch which is the main purpose of my posting. But glad to say the pressure is off having to replace it straight away.
It seems there is nothing too complicated about the switch and what and how it switches. So maybe I'll look at the 5 wire switch, which is widely available, as I think I can wire it up to match the original. I have heard of switches having resistors built in. Without which the engine won't start. Not too sure how that works but no sign of such complications with this one thankfully, so adapting a 5 wire one may not be a big problem.
Mikaw, thanks for your interest and concern. I have worked on and had accidents with very high current equipment so maybe I have got a bit blasé with a small low voltage bike system. I am very careful though rest assured more as I do not want to damage my trusty machine than anything. I often use low current fuse wire to make initial connections in case I have it wrong and am shorting out the power. Then put the real wiring in. Your suggestion of a cloth over the mudguard was welcome. Easy to rush on and drop a spanner causing damage.
Cheers Bob.
PS. Can you tell me where the donations page is. I can't find it in any of the drop downs on this site? I can be so blind at times.