I had one of these years ago. It's a good engine. On mine, I was tweaking the LSN ever leaner ("in") to get it "better" untill I noticed the high end was getting difficult to richen. What happens is that the LS needle going in too far starts blocking the fuel flow from the HS needle. To get back on track, back out both needles to get a rich run.See that you are able to get slobbering rich on the high end, and then start leaning it a little at a time, HS and LS. Lean the LS untll you get good transition, then stop. Lean the HS for good running, and you are good to go. You should always have the capability to richen the HS, if not, your LS needle is too far in.