[john hall]

Playing with the choke doesn't make any difference. I didn't pull the plugs back out today, last go around we could certainly tell a temp difference in them. The backfiring seems strange to me because it only happens on one of the cylinders. I'll probably pull the carb off the KT and give it a try later in the week--hopefuly that carb is in decent shape.

I've found too many weird things with this mower that are making me concerned:
a 1/4" bolt stuck in the fuse holder
fuel bowl had been reinstalled with some sort of glue (really good stuff whatever it was) but no O-ring.
The breather matl was laying on the valve spring--and was on the wrong side of the breather plate (reed valve)
2 of the engine-to-mounting plate spacers were missing.
Wiring harness was sliced and diced with an auxillary wire to solenoid just to bypass the pedal switch--why not make a jumper wire, less work.
PTO crank seal installed way crooked
The guy I got it from had paid someone to "work on the carb"

Anyway this type of work has me wondering what else weird could have been done wrong. The weird part is the machine isn't beat or banged up or no crazy modifications, just some mechanic work causing me to scratch my head.

Thanks for the ideas thus far, I'm listening to them all believe me. Checking the cylinder temps then swapping carbs are probably the 2 things next to do. After that, pull the heads to see the valves?