YB 100 only runs with choke on

Dear all

just joined, sorry for the naivity

I have just purchased an 1989 yb100 that needs some work which that is the reason I purchased it

the guy who I got it off has had it running, as so have i

but it only runs when the choke is on, and dies when switched off.

i want to give the bike a complete overhaul, so starting from the beginning isn’t an issue.

should the throttle stop screw be full tightened

Also when I remove the bung on the side to get access to the pilot air screw, it would seem that this is also fully tightened and will not budge.

once again apologies for my naivity

any help would be great

regards

martin