I have a garden tractor with a B&S 44N777-0124-E1 VTwin engine. When I bought this (second hand), it ran for about 20 minutes and then would stall. Sometimes it would take a long time to get it started. Started by changing the spark plugs (later the ignition coils) and placed inline spark testing on both cylinders - not a problem. Changed the fuel filter, made sure the fuel lines were not blocked and flushed the gas tank and then bought a new gas cap (no vapor lock). Removed carb and initally replaced with an aftermarket Nikki. Noticed that the intake manifold was warped - originally sealed with Permatex but later replaced intake manifold with new OEM. Since I have bought a new OEM Nikki carb and still had issues with surging - only seems to have worsened. I then decided to rebuild (new o-rings, gaskets, etc.) and clean my original Nikki carb - found that the o-rings on jets were loose and several ports clogged...did a deep clean with cleaner, drill bits, wire, etc. Replaced and it ran better for about 10 minutes and I was able to cut the grass until it stalled again. Continues to stall. I'm now planning on adjusting the governor (springs seem to be okay) - but will reset. Also, I plan to check gap on all 4 valves and reset back to 0.005". After that, I'm at a loss - fuel solenoid works, has gas in the bowl, don't see an vacuum leaks (with starting fluid). Wiring okay (no shorts), ignition seems okay. Any ideas? They are appreciated!
Thanks - I'm assuming you are referring to a blown head gasket? I have considered but have not seen smoke from dipstick or a lot of heavy black smoke, nor leaking of oil anywhere. Are there other ways to make sure the head gasket is okay...other than pulling the head? Thanks.
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Check oil level on dipstick & smell for gas in oil.