Problem solving

[Zander]

Getting to grips with the nitty gritty now, so decided to check carb setting, as the tick over  is a bit fast for comfort.  First check was cable routing which could be a little more natural, but it's not affecting slide position as it is.  Next check was choke slide which is well out of the way, so ok. Slide stop next - slide found to be off the stop, so unable to slow engine using that.  Finally, pilot screw. This was only 1/2 a turn out, so set it to one and a half turns out, but still not really satisfactory, so I removed carb to check for crap and blockages, and to check jet sizes, which were all as standard.
Replaced carb, but still running too fast off slide stop.
As all seems ok in the carb, I'm now wondering if I've set the ignition timing a bit out.

[JulianS]

Sounds like you need to adjust the throttle cable length to allow the slide to rest on the stop and then adjust the stop to set a suitable idling speed.

[Zander]

I've adjusted cable length as you suggest, but even with the slide sitting as low as it'll go in the carb body, with the stop wound right down, the engine is still ticking over too fast for comfort.

[trevinoz]

Is the slide too sloppy in the body and letting air around it?

[Zander]

I noticed a bit of wear on the slide, so it could be, or contribute to the problem.  I'll do a thorough check tomorrow 

[BSA_54A10]

Get a trigger pack & some bulk WD 40 or similar ( do not use pressure packs unless you need an eyebrow trim ).
With the engine running flood the manifold area with WD 40 then come back to the carb flange then finally the top of the mixing chamber.
If you get clouds of smoke then you have an air leak making the engine run lean & fast.

[Zander]

Good tip - thank you
By an amazing stroke of luck I have a brand new slide for the 376 carb, albeit a with a no.3 cutaway, so I fitted that and obtained an immediate improvement whereby the tick over can now be adjusted. Thanks to one and all for pointing me in that direction