Hi AVB, MF, Tyler and Mod BigTed,
I'm really stoked by all your indepth responses. I shall take some photos today and post them up here so you all can understand which model engine and carby I'm playing with here.
The thing that makes me feel that the spark arrester is blocked is that with both carby's the symptoms are exactly the same and that makes me feel that something else bar the carby is amiss. I do feel that the carburettor requires a full fine tuning as I would expect that is the case after a full disassembly.
I'll go through it all again armed with the info many of you have provided and report back at the end of the day along with the images.
Once again I can't thank you guys enough.
Cheers,
BB.
PS. For AVB,
I used throttle body cleaner with the long tube attached to the spray can to blow through all the holes and there were a few gelled up spots which are all clean and clear now.