Trimmer “Mtd-600”: Repair Advice.

I will share how I repaired the trimmer MTD-600 (problems with ignition), maybe someone will come in handy.

At first, nothing is clear, the trimmer does not start, does not even sneeze.

  • I checked the compression (to eliminate the breakdown of mechanics in the cylinder, rings, connecting rod, etc.). the compressor shows 10 bars after a couple of jerks. this is quite enough, the cylinder-piston-rings are fine.
  • Gasoline is supplied through the carburetor. the candle is wet, and the top of the piston is wet.
  • The candle is clean; the gap is 0.6 mm. When scrolling a spark goes. an inverted candle (its thread skirt) is temporarily connected with a cylinder with a wire, and we twist the starter. everything is in order.
  • Compression is there, gasoline is there, there is a spark, and it doesn’t start up. it means there are problems with ignition (ignition angle). But the moment of ignition on trimmers/chainsaws, is not regulated on such two-stroke! Therefore we sort the trimmer. we take away the engine from a shaft with a starter. Magneto opens. a coil with two pins and two “cheeks” of the core, which at some point are closed by a magnet embedded in a flywheel for which the starter clings when scrolling. It was found that this closure (it can be seen. it is the combination of both ends of the magneto core with such well-selected magnet areas in the flywheel, the gap there is a fraction of a millimeter, while in other positions of the flywheel above the magneto remains several millimeters) upper dead center) of the piston (this point is easy to find by turning the shaft, observing the piston into the hole in which the candle is turned out). That’s breaking! Magneto should close somewhere near the “VMT”, and it closes when the piston went somewhere down! Turning the nut, pressing the flywheel to the tapered shaft. It is detected: a pin is cut off, which fits into the grooves on the shaft cone on the outside and the internal cone of the flywheel and which rigidly mates them in one position. Flywheel “cranked.” Most likely, someone with too much foolishness jerked the starter, and the flywheel came off, knocking the ignition down (American trimmer, it should be easy to start with a child, power is not needed, but tractor drivers with experience of starting a diesel engine comes across, for them this machine will be soft)
  • If there is no standard pin, then it is necessary to make it yourself: a small plate bent with the letter “U” so that it enters two slots in the flywheel with its “horns” and a curved part into a wide groove on the conic shaft. It is empirically selected for its size so that the flywheel is lowered onto the shaft and securely fixed.
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We check the closure of the magneto and “vmt” closure, tighten the flywheel nut, assemble the trimmer, start up according to the instructions.
Everything should work.