I didn't have the truck running, if that matters, just joined the batteries with cables- wanted to rule out lack of cranking amps from the issue.
John not sure what you mean by choke circuit- there's a knob to pull out but that's it? I can pull the carb though as a next step.
Matt we have the same engine- the pic above is from a 450, but posted here to show the torque limiter.
82 fj40, 99 uzj100, 06 gx470
97 DR650, 05 525EXC, 01 XT225, 09 TTR125, 07 TTR90, 07 CRF50