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tacomac

no fire after shut down

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tacomac
the 16 h.p. twin on my allis T-816 runs and mows just fine but if I shut it off, there is no fire to the plugs untill it cools off and then it fires right up again. Anyone know why it would do that? thanks for your help Earl

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1Litre
If it has a maganatron on it it may be just that. You could have the coil tested and just replace the magnatron. The later coils have the magnatron built into the coil and that means a coil assembly anyway. I am parting out a 5216 if would like a used part.

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Al
Hi, It sounds like a coil to me. I would suspect it you were to look at the spark voltage with an oscilloscope, I would suspect you would find when it is running it is much weaker than when it is cold. If this true, you might have enough spark to run, but when you shut it off, if doesn't have enough spark to start. Usually what happens is that the primary coil is wound with varnish insulated copper wire. This is the primary of the coil. The secondary is wound of very fine wire and some coils about 10 thousand turns of very fine wire. Sometimes the wires will expand with heat and the varnish will fail due to the thermal expansion of the turns. If one layer shorts to the next layer it creates the effect of a shorted secondary loop and this absorbs much of the energy that is normally induced into the secondary coil, greatly reducing the coil output. Another thing that happens is that the secondary sometimes has turns short and the same thing happens. Another scenerio that sometimes occurs is that the high voltage that increases with each wound layer. happens when the secondary output arcs back to the lower windings of the secondary coil. This kills the high voltage output. Al Eden

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tacomac
Thanks for the information. How hard it is to get to the coil on a twin 16 vertical shaft, I think it is about a 1982 model? I'm used to working on Kohlers where the coil is visible. Earl

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