Check that the comps are ok, check that the float height in the carb is correct, check for vacuum leaks, cap and rotor is ok? let me know what you find.

Thanks, what is meant by comps?

cylinder compressions,

Yes all good, I've also been asked if it could perhaps be a sticky valve, what is your take on that?

could be, a compression test would normally pick that up because if the valve was sticking and not closing fully the compression on that cylinder would be down.

Ok let me double check

Ok compression is 1000, 1000, 600, 800. Does this indicate gasket or rings...no smoke is being burned.

The 600 is very low, this will be the problem, you need to do what is called a leak down test, this is where you have an adaptor that screws into the spark plug hole, and with that cyl at TDC you have low pressure compressed air pumped in, not to much or the piston will be forced down, then you listen in the exhaust and inlet for air hissing, if it is leaking you will hear it. Also you can do a wet comp test, this is when you add a small amount of oil into the cyl, just enough to seal the rings, then re test the comps, if they go up it will be rings in they stay about the same it will be valves.

Thank you, will do this asap and give feedback. Thank you for the prompt and accurate advice.

Your welcome and thank you for the donation, good luck with this.