I'm still back at the carby on this one Jaffa. The bearings wont affect revving performance unless they are binding, but then you'd know that by just pulling the starter cord. If the seal is shot in the lower bearing it will cause overrevving issues just like a bad diaphragm or a starter seal. You've really got to get a complete working carby and keep it as a test unit for situations like this.
Try some of the following, not necessarily in any order:
Is the poppet valve set to "C"?
How's the air filter?
Have a beer and think about it some more.
Try it without a muffler(wake the neighbours), but watch out for the shooting flames.
Try a known good working spark plug.
Have another beer and pray to the mower gods.
Does it over rev with the vacuum line to the diaphragm disconnected?/ If yes, try a diaphragm cap with the brass restictor in it.
Last edited by bigted; 11/02/14 10:43 AM.
