ORIGINAL: iron eagel
There is also a low end adjustment, this is on the throttle barrle itself with the thottle closed this adj need to be closed also (read manual). I had the same problem with my OS 46 FXI from a Nextstar and this fixed it.
I would be it is too rich at the low end.
Thanks, I will check this later. From memory, the manual says this adjustment is preset at the factory so thats why I didn't adjust it, but if you say you've had the same problem and this fixed it, it could be it. Thanks.