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John Deere 212 with cast iron Kohler engine, probably 30 years old. Finally had to have the points changed an replace the ignition switch. Ran fine until warmed up and began to mow then began to miss and finally backfires killing engine--never acted this way before. If cold runs fine, warms up powers down and quits. Any suggestions.

Ignition coil...!

Doc , start with the troubleshooting charts in this forum.

I moved your thread to the Small Engine & Mower Repair Forum. :smile:

countrydoctor said:

John Deere 212 with cast iron Kohler engine, probably 30 years old. Finally had to have the points changed an replace the ignition switch. Ran fine until warmed up and began to mow then began to miss and finally backfires killing engine--never acted this way before. If cold runs fine, warms up powers down and quits. Any suggestions.

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I've got an old 14 HP cast iron Kohler side shaft engine. Also I work on a neighbor's mowers that also have them, one a 12 and the other a 16HP. When they start up cold and run fine, then start cutting out and quit when hot it's usually one of two things. 1) coil going bad. Resistance is low when cold, when metal heats up the resistance increases and thus electricity can't flow and it quits. Repeats cycle from cold to hot. 2) Could be a valve not getting enough clearance. Will run when cold, when metal heats, it expands and thus lose compression because it can't seat properly and sputters and dies, might backfire through the intake and stop. When it cools down you get valve clearance and it will start and run. The hotter it gets the less power it gets and finally quits. Check valve clearances cold and hot.