B&S 12.5 hp twin carb question

"The carb also has a solenoid type thingy, that has an electrical connection to it....The electrical connection pulls a little plunger that seems to shut off the gas. ..Anyone know what this is for?..."

It is to prevent "after fire" caused by accumulation of unburned fuel igniting in a hot muffler at shut down. These are relatively expensive and are not needed, didn't have them at all until fairly recently. Lean mixtures brought on the "need". Just idle the engine for a little bit before turning off.

Cleaning in solvent and checking the wiring MAY bring it back to life.

Walt Conner

Still having trouble getting this heap to run right....It seems to want the choke on to run decent. As it gets warmer, less choke, but I can't open the choke right up or it will stall.....Maybe a vacuum leak somewhere?

Also, I am not sure if it has the right spark plugs...It is a B&S twin I/C 12.5 hp......Anyone know the proper plug? It had 1 Champion RJ12C in it.........

Hello poncho62, sounds like the carb is cruddy inside. For it to need choke to run right, means it is running lean, IE clogged jet and or fuel passages. Proper way is to disassemble carb and put a kit in it, around $20-30. Ghetto method, unscrew afterfire solenoid, spray carb cleaner through now visible main jet, spray carb cleaner in and on everything you can for the carb. Dump a load of SeaFoam into the fuel. I have done this before. I am not proud of it, but I have done it. :fing02:

As for the plug, most, if not all Briggs flatheads, at least the aluminum block engines, call for the Champion RJ19LM plug.

Good Luck!

Seth K. Pyle