"I had that same problem with
"I had that same problem with my BF75, an earlier version of the same engine. I ended up taking my carb apart FOUR times before finding the blockage. Running carb cleaner thru it is NOT enough. The blockage is in the idle circuit, which is a seperate (winding and twisting!) carb circuit than the main one. There is a fixed, not removeable metering jet in that carb (at least in mine) that has a very tiny hole that does not respond to the usual soak and blow cleaning. I ended up cleaning it up with a 30AWG copper wire, i.e., a single strand from a multi strand copper wire.
A can of "canned air" available from Staples or RAdio Shack with the plastic straw extension affixed is a handy tool as well. This is to be used in addition to the wire, not instead of."