Small Engines (Lawn Mowers, etc.): 12.5 Tecumseh OHV125, crankcase breather, feeder tube

Question
Tecumseh 12.5 engine Mod.# OHV125  206603A   (H)Wouldn't run unless fully choked.Backfires 1 time when first starts I replaced carb bowl kit (new preset float,valve & seat,feeder tube) Free flowing fuel to carb. carb has NO adjustments.I checked flywheel pin & all conections for aie leaks &fuel cap vent.I need valve lash settings.Runs when primed then dies. I have never seen this type carb.Thank You for any help You might have. Deane

Answer
Deane

Check the exhaust outlet if it is clogged with carbon your engine will not run good.

Crankcase breather passing oil.
Possible causes:

  1. Too much oil in crankcase.
  2. Engine speed is excessive.
  3. Oil fill cap or gasket is damaged or missing.
  4. Breather mechanism is dirty or defective.
  5. Piston ring gaps are aligned.
  6. Piston rings are worn.

Engine backfires.
Possible causes:

  1. Carburetor set too lean.
  2. Magneto is not timed correctly.
  3. Valves are sticking.