Loncin 87cc engine

I am servicing a mower fitted with a Loncin 87cc engine. It has poor starting. Have cleaned air filter, fitted new plug etc. Cleaned carb by squirting with carb cleaner only. No needles, compressed air, no screws undone. Refitted and it stated but now revs flat out at any throttle setting other than tickover. The governor seems to be fine. Any ideas please?

Either the governor/ throttle shaft is binding, or on some carbs there are extra holes for the linkage and in some cases it is possible to connect the link on the wrong side of the throttle shaft causing the governor to open the throttle instead of closing it. Or you could have multiple linkage holes but connected to the wrong one.