Hard starting - black smoke !
 

Hi dear KLRists,
Following a broken foot, I just restarted my '91 KLR 250 (21,000 km or 13,200 mi) after 18 months of inactivity.
I changed a lot of things, including the timing chain, the chain tensioner, all the gaskets, the packings, etc. I also adjusted the valves very finely, put in new oil and a new filter, etc. I also changed the fuel and cleaned the tank.
When starting (with difficulty), it sputters, doesn't idle, smokes black, and the (new) spark plug is black and wet.
I thought the choke was perhaps stuck in the open position.
Could anyone among the group's technicians give me their opinion?
Many thanks in advance. ;)