If you have a Stihl saw with the older style tank vent that has screws in a tube, you may want to consider continuing to use it after a rebuild instead of going to the newer style duck bill vent. The new style will not release pressure from the fuel tank, and it may build up enough pressure to overcome the popoff setting on the carb and flood the saw. This is what happened to me on an 025, flooded the saw badly when it went from cold to warm conditions. Put the old vent tube back in, no more problems. This may be carb dependent, it is happening on a Walbro, whereas the ms250 I have that uses a Zama does not have any issues with the new style vent.
This could be solved by going to a stiffer needle valve spring on the Walbro, but then it may adversely affect carb tuning, so the simple solution is probably the best.
This could be solved by going to a stiffer needle valve spring on the Walbro, but then it may adversely affect carb tuning, so the simple solution is probably the best.