Then, I would suggest your timing is some degree of 180 out.It pulls easily with no plug. I used a new Honda tensioner and retried the old one as well. Same result
10K is nothing for these machines. My rebuild (top end) was around 30K . I'll dig up some photos, the piston looked brand new, rings were in spec, but my cam decompression mech had seized. I could have gotten away with just a new cam but threw good money at it anyway.