running[very] rich

Are you using the correct No4 Slide? After that, all things equal, I would look at weakening the mixture (Left turn) but don't go too mad with this or it will nip up. 1/8th turn at a time.

The level should be on the dimple (assuming monobloc here).

You haven't by any chance fitted a fibre washer between the float needle seat housing and the float chamber body have you? On original monoblocs* there shouldn't be one here, and that would probably give you your 5mm.

This is the rig I used and you can see there is no washer under the housing.

http://www.iansoady.org.uk/Arrow/images/floatlevel1.jpg

A little while ago Richard Negus, who is a well respected Norton chap, made exactly this mistake on a bike he was rebuilding for a certain large bearded magazine editor and the error was shown in a photo of the rebuild in the magazine. So an easy trap to fall into.

*I believe there is one on modern replicas.

Have youlifted the air slide?

John, 5 mm above the dimple is not correct. If the float is riding up that high, I may be touching the cover screw boss inside the float chamber which will not allow the needle to seat properly. As said above, NO washer under the float chamberneedle housing on original Monoblok carburettors. Only the after market modern ones have a washer.

Another thing to look for is the tickler pin. Some are longer and will stop the float and so stop the needle shutting off.

Paul

Just a thought - you do have the little spacer fitted on the float spindle? It's easy to leave this out and it can cause all sorts of problems (as I know.....)