quite a few designs to this carb - my 'autoreturn choke " troybilt mower has a lot of moving/interacting parts that are hard to see as you take it apart, and a drawing for it is hard to locate on the internet.. Mine has less gaskets than most of the diagrams i found, from engine I have only: a paper gskt, plastic insulator, sheet gasket, carb, gskt, steel spacer, second gasket, then airbox. On reassembly, the black choke control on top of the carb has a top pin that has to sit left of the 3" choke finger (steel bar). The choke position spring looked correct too, but it popped out of the drillhole but was still hooked on the arm. It looked OK, but wasn't able to force the choke to reopen properly . Once I rehooked it in the drill hole, all was fine. Finally the govenor rod and spring were twisted around each other- they should be parallel, with the stiff rod thru the coiled portion of the spring only.

***"What will removing the kill harness from the coils and do a test run tell me?"*** That was brought up due to the fact that the ignition system here (in vee twins) is configured as 2 separate magnetos...........joined together into a single kill wire circuit, for convenience when shutting down the engine. With magnetos, you must ground one leg of the primary coil circuit in order to "kill" the spark generation. A problem or obstacle arises when you have an engine configured with multiple cylinders and multiple magnetos. The focal point in this is that in order to kill both magnetos with a single kill wire circuit, you gotta join the kill wires from each magneto together so that both mags are killed simultaneously when a command to stop the engine is issued. This "command" might come from the ignition key switch when the machine operator turns the key switch to OFF, or.......the command may be issued by one of the safety interlock switches or relays (depending on the make of machine). The problem or obstacle when simply connecting the kill wires from each magneto together in the form of a "hard wire" splice is that connecting the kill wires together will cause serious and detrimental operating effects on BOTH magnetos when the engine is running. In theory, the kill wires can be kept separated from each other by providing a separate kill wire circuit for each magneto..........and running the pair of kill wires all the way to a specially designed key switch having 2 individual kill wire terminals (1 for each mag) which remain completely separated from each other until the key switch is turned off. Now, that in itself is a bit more complex than the single wire system that is industry standard.............but it gets worse. Because in modern OPE, there is a safety interlock system, with multiple switches wherein each switch can issue the command to kill the engine spark.............each switch would have to have double circuits for the magneto kill function, or a master relay for magneto kill having 2 separate circuits would have to be employed. All this double wire stuff and special switches in various locations could conceivably add hundreds of dollars per unit built to the OEMs cost of manufacture, and that cost would be passed on to the consumer. To overcome this obstacle, Briggs overcame the problem by connecting the kill wires together with 2 diodes, so that the separate magnetos stay separated electrically from each other during normal operation (and therefore do not interfere with each other's spark making business). In this manner, the kill wire function can be controlled by the same simple type of switches now in use. Now, for why this is something to be concerned about if you own one of these Briggs engines. Occasionally, one of the diodes can become defective. If becomes defective OPEN, there may not be any noticeable difference in how the engine runs, but when trying to stop the engine, one cylinder may continue to have spark. If this is on an engine that has a fuel solenoid, you might not even notice that you have a cylinder still getting spark, because the fuel solenoid stops main jet fuel when the key is turned off, and the pilot jet fuel is not enough to keep the "live cylinder" running against the dead cylinder load. But, if one of the diodes becomes SHORTED, or any sort of continuity in both directions develops, there will be some problems in how the 2 cylinders run. Tomplum's suggestion of isolating the magnetos from their kill wires is a way to determine if there is a problem of 1 cylinder being dead. But to separate the mags from their kill wires properly, you must disconnect each wire from the magneto itself, and that means taking off the flywheel cover. If you remove the flywheel cover, put it back on before running the engine or you will overheat it because with the cover off, there is no air flow across the cylinders. You will also have to choke the engine to a stop if running with the kill wires removed. This post was edited by mownie on Wed, Apr 9, 14 at 13:21

You said you drilled it out? How big a bit did you use? Common sence would dictate to use the same size bit as the jet hole? even if you use a bit bigger would the jet adjustment screw compensate when you adjusted the mixture? I would of tried to adjust the carb. after I cleaned it, which IMO was probably the problem all a long. SUrging IMO usually is an adjustment problem and if that don't fix it dirty carb.

"It started acting funny and would only run with the choke pulled out a bit" "ran like a dream for about thirty minutes and started hunting and surging and barely idling" ========================================================== You suspect valves or the coil, but the problems you described are usually indication of a lean fuel air mixture. If the fuel tank is located above the engine, pull the fuel line off to see if a steady stream of fuel is delivered. Let the fuel run into a jar. Examine the fuel sample for signs of water. Check the hose for cracking. Clip off the ends of the hose to eliminate cracking. If fuel flow is weak, there may be small stones or grass in the fuel line. Replace the fuel filter. The fuel pump is vacuum operated and sometimes the vacuum hose is loose and vacuum pulses do not reach the fuel pump. I usually remove the fuel tank for cleaning and renew all that old hardened fuel hose. If the tank is remounted, the same inspection applies. If there are cracks in the fuel line, air can be drawn into the fuel system. Sometimes an old fuel cap does not vent and fuel is not delivered to the engine. This engine is equipped with a high speed mixture adjustment as well as the idle mixture adjustment. As you sit in the driver's seat, the high speed adjustment is located on the left side of the carburetor. The idle adjustment is located on the lower forward side of the carburetor. For high speed surging, open the main mixture adjustment about 1/8 or 1/4 turn to see what happens. You may need a service manual to follow the exact adjustment procedure.