200s ran but now won’t start

[Sperdue]

I have a 84 200s that ran good but now I can’t get it to start. A while back it just cut off me and wouldn’t start but I put a new plug in and fired right up first pull. Now a new plug does nothing. I have cleaned the carb and put new jets but nothing. Not sure if it’s anything but a few times trying to start it, the pull start has snatched back and nailed me in the ankle. It has spark and new plug but what should I try next? I have also put a different gas line from tank to carb.

[AMSinator]

Verify Suck-Squish-Bang-Blow.
Use KISS diagnostics.
Just because "ran good" means a little, but ......Snatching start rope back is a clue of lean fuel or firing at wrong time or blowing back through intake tract due to poor sealing, wrong ignition point &/or combination of both.

1st; You Must have a Mechanically sound engine,

Meaning all aspects,

When was last a) valve adjustment b) Leak down test c) Compression Test by competent Tech?
Valve Timing & Valve clearance are correct
Verify engine mechanical valve timing,
Verify Timing chain, Cam Gear AND tensioner operation & Quality.

2nd; Ignition, Quality of spark, connections-wiring, Ignition Timing set still.

3rd; Fuel Quality.
No contamination from other fuels such as Diesel or 2-smoke mix, water or trash in tank, supply volume quality etc.
Sample of fuel from bowl should evaporate totally when allowed to sit ibn open air and leave "No oily" residues, like diesel/2-smoke will.

AMSinator
https://www.amsoil.com/?zo=352885