I have replaced the diaphragm & spark plug and ran with the air cleaner off.
Still has the same symptoms.
I though the muffler may have been choked, as the base was covered in black soot when I got it. (I put an exhaust deflector on it)
I also tried running it with the muffler off with no change.

I am thinking I might try a know good carb and tank set up.
Would lapping valves help?

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