Motoplat coils

[Lew Mayer]

Are motoplat coils interchangeable? I have a small coil on my 73 Jackpiner but I have a spare "large" coil I want to try for test purposes. I think I'm losing spark at idle at times. Any thoughts? It's not a fuel problem.

Lewis A Mayer

[Paul Danik]

Lew,
   The later coil can be exchanged with an earlier one, but not vise versa.  Has to do with a diode being in the later coils and not in the early ones.  If your unit is losing spark at low RPM you may need to have Dane check it out and maybe remagnitize the flywheel.
Paul

 

[Lew Mayer]

Which one would be the later coil, the larger coil or the smaller one?

Lewis A Mayer

[Doug Wilford]

Smaller

 

[idiotboy]

The red wire coils have a diode, the black wire coils do not.

 

[dirtbike]

I thought that the red plug wire larger coil was the later and the smaller was earlier.
The red wire coil can be used with any of these stators. The other not. Only with the earlier that have the diode in the stator.

 

[TGTech]

Lew,
The Motoplat coil thing is sort of complex, but there are some rules that can be used. First off, if the coil has a red spark plug wire, it can be used on any Motoplat magneto. There are two different "shapes" of coils with red wires, but both are interchangeable.

The two differ in size a little bit, as well as having their connecting spades in reversed order. The earlier version, has the large terminal between the small terminal and the spark plug wire. The later version, has these positions reversed.

In the early 1980's, Motoplat decided to reverse the polarity of the system, and at that point, they went back to the black spark plug wire. They left the rest of the coil the same, but because the spark plug wire was again black, like the coils prior to 1974, this has caused some confusion. If you have a coil with a black wire, but the small terminal is between the spark plug wire and the large terminal, it will also work with any Motoplat magneto.

The black wired coil that will not work, are the ones with the large terminal between the spark plug wire and the small terminal.

I hope this has been of some help. If you need more information or clarification, please give me a call at 440-988-4474.

Dane



Edited by - dandk on 06/08/2003  09:55:36 AM