Small Engines (Lawn Mowers, etc.): lawn mower, jumper wire, speed jet

Question
I have a 12 hp 36 inch murray lawn mower( briggs engine), which i got from a friend. it was smoking so i put a set of rings in it & it starts & runs fine But when i go to engage the blades the engine stalls , the blades are free to spin,the governor seems to be working fine it is pulling the carburator lever back when it is getting the load from engaging the blades.do you have any ideas on what i can do to solve the problem ,it seems like it is not getting the gas but i don't know, thanks for your help... Ray

Answer
If you are sure there is nothing in the drive mechanism for the blades (blade brakes, idler pulleys, blade spindles, etc.) causing excessive load, there are a couple of things you need to check.  There could be a problem with the safety switch on the seat (if equipped).  If you bypass this switch (remove harness connector and use a jumper wire in connector) and try to engage the blades again.  If this solves the problem, you will need to either replace or adjust the seat switch.  If this has no effect, you may have a fuel issue.  If the carb is equipped with a high speed mixture adjustment, open it 1/8 of a turn at a time until the engine can maintain it's WOT rpm under load (sufficiently rich).  If there is no high speed mixture adjustment, you will need to clean the carb as it is likely the fixed high speed jet is partially blocked.  Hope this helps.