left cylinder running issue......carb??

I have not read this thread from the begining, which funnily enough strongly mentions left misfire/dropping out...

You have eliminated a HT loss with a pair of red neons ?

I would not put the float chamber bowls in an ultrasonic bath to safeguard the overflow tube from possibly splitting.

For your own interest( and others), track ever carb drilling/passageway with photo and description, oil can method can/has shifted some crap blockages as well as carbs submerged in redex fuel/carb strong mixture for a few days, chemical cleaner...

Once you have routed all passageways, air as well as fuel as well as mixture, you should be able to understand how the carb works in detail...

As you know some jets some with diffusure tube and holes are pressed/shrunk in place...

Take note of the comment about the brass mixture screw O RING and the possibility of a bit of it blocking the works...

I wonder what those two holes are, some progression to be made methinks...

Going into detail will help you...

after looking at it laying in the garage in disgrace I had another go today, carbs off again. All seems good, the idle mixture screws are good as are the o rings. The passage way into the carb is clear, the idle jets are clean and good and carb cleaner dribbles through them clear.
Bike starts on choke and runs on both, the down pipes before the collector both warming up.
As it warms and I drop it off choke it idles but only on the right cylinder. 
So and issue is still there!
Doing my head in this one 
as refresher. valves were set, new coils/leads/plugs and I have switched over to prove it is not caps/leads/plug etc. Compression good too on both.

Wider throttle and it runs on both cylinders.

I think somewhere there is a blocked passageway on this carb in the slowrunning circuit. Off they will come again.

Baffled!

This method has been mentioned many many many times before, and even in this thread.

I cannot afford a 50/50 redex/petrol mix even when redex is on offer in the likes of Lidl etc..

After the carbs "outside' crap has all been removed, I totally submerge the stripped carbs in a strong mix of this redex/petrol mixture in a suitable container adding clean objects to displace fluid, an economy measure, and leave for a few days, lifting out the carbs and resubmerging three times a day.

It works.

I also use the squerty oil can and oil method to make sure all drillings etc. are clear.

Messy but works for me.

To further aid economy, get some long float bowl screws to make "feet" so carbs are partially submerged and passages filled with the redex/petrol solution.

The amount of crap seem on the container floor can be quite surprising as well as the colour of the solution, "coke" like.

I also like to add a mix of 2t oil, redex and valve seat protector mixture to every tank of fuel, a tomato sauce bottle lid full X 2 for a tank full.

Works for me.

Have you sussed out where all the passages go and what function those progression holes
Do ?

Filling a fitted float bowl with the solution fluid will not fill up the "raised" drillings with the mentioned chemical cleaner.

I assume the carb throttle butterflies are "balanced" ( bench balanced using balls ).

What vacuum value is shown on the gauges ?