Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

Sign in to follow this  

Bad Coil or motor?

Recommended Posts

Got 7119 and while idling it seems like it is missing but when running it seems o.k. Uncle says the 1/2 of coil is bad and one wire isnt firing the plug. Since coil has two plug wires coming out I sorta believe him but wanted to check with you guys. I plan on starting and pulling the plug wires to see if spark also.,

Share this post

Link to post
Share on other sites
If the coil itself is bad, neither wire will fire. If one wire is grounded, or one spark plug is grounded by fouling, the other will continue firing. If one plug goes open or a wire breaks, neither plug will fire. As you can see in the picture below, the only difference is that the output coil of a single cylinder unit has one wire internally case grounded, while both ends of the coil go to plugs in the double coil.

Share this post

Link to post
Share on other sites
Rod, Are you sure that is how the KT-19's coil is configured? It doesn't make a lot of electrical "sense". I would think one side of the secondary would be grounded and the other would "Y" off to both spark plugs. Alternately, I'd think the secondary would be center tapped to ground and then each plug would share 1/2 the windings. I haven't dealt with the KT series very much. Tom(PK)

Share this post

Link to post
Share on other sites
Tom, This is the way the Onan coils and nearly every motorcycle coil that I've seen are wired. Remember that a plug is really ground with a spark gap. The only ones that I have worked on that have separate or divided coils, also have separate triggers or points. We tried to use two separate coils on a single set of points once. It ran but not smoothly. Problem is that the two coils have different resistances. Lowest resistance pulls the most current and takes the most charge. The double coils I showed above always fire the same spark through both plugs. Only the plugs themselves can make a difference.

Share this post

Link to post
Share on other sites
This topic is now closed to further replies.
Sign in to follow this  

  • Who's Online (See full list)

    • simplewrench
    • 720nut
    • kwt
    • NandoG
    • ShaunE
    • Tom45
    • Md1227
  • Today's Birthdays

    No users celebrating today
  • Recent Status Updates

    • Paul M.Murphy

      Paul M.Murphy

      Hello glad I got on this site. I hope to upload a couple of photos of my Simplicity Broadmoor 
      Model 707 Tractor. I have replaced all the belts on it and installed a new ignition switch.
      Have a mower deck which was in poor shape , repaced a couple of bushings and welded the
      deck where there was some holes. The tractor and mower deck came from a friend and the 
      mower deck metal was getting pretty thin. Some new metal was put in it and we also undercoated the underside of the deck. This was done by my friend Greg Toulman.
      I have not put the mower deck on the tractor yet, waiting for Greg to come home and give me a hand. Can you please tell me if there is a manual for the mower deck and where I could get one.
      I would also like to get some moon wheel discs as well.
      I will try and down load some photos of the tractor when my wife shows me how to. 
      I really love driving this tractor and also how well it is made compare today's tractors, especially the flexible rear end and the rollers.
      Tell the next time 
      · 9 replies
    • jbrooks

      jbrooks  »  Talntedmrgreen

      folowing  this from a link at the downloads.  I just rescued an AC 920 with the lambodini diesel. I can' t download  yet .  Where did you find the PDF copy you posted. . I would like to figure out how to adjust the injection pump. 
      I assume it's a bosche, correct
      · 0 replies
  • Adverts