I had a look for a local firm to recon the injectors only to be told some of the internals are so hard to get its just about impossible, so found some brand new from paddocks for about £25 with a surcharge .
These arrived today so fitted them straight away, reset the max fuel bolt to its original position and WHAT A DIFFERENCE!!.
They might well be chinese but now it only smokes black under heavy load- I could still back off the max fuel a bit but probably won't bother till I have run it around a bit.