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Poor Spark Point type ignition

bill_w

bill_w

Advanced Contributor
Just a general question..what is usually the major cause of a poor, yellow spark? Bad coil or condensor, or something else?

Thanks,
Bill
 
The windings inside the coils are made using " magnet wire " and the wire has a thin insulating coating on it.-----Shorting between windings reduces spark output.-----------Other causes are---- #1 points opening at the wrong time ---#2 dirt / oil on the contact surfaces---#3 wrong air gap on the heels.----------#4 bad condensers.--------#5 sheared flywheel key.---------Coils are best tested on a Merc-O-Tronic ignition analyzer or similar.--------Luckily the OMC replacement coils are cheap and plentyful.----------Just did some work on an old Martin 20 single cylinder.-----Point cleaning was all that was needed to restore proper spark.-----------They sure knew how to build / specify their coils in the late 40's early 50's
 
This is just a general question, and really not related to an OMC motor. Truthfully, it relates to a 1972 JLO 400 Snowmobile motor. It was running great, then started running on one cyl. The one cyl has a yellow spark, and is not firing when the motor is running (I can pull the plug wire off, and it makes no difference). I was just wondering what parts I should be looking at replacing first.

With all of the older OMC's I've redone, coils, points, condensors, wires and plugs are just automaticly replaced. Parts for the JLO are harder to find, so I am just trying to do the repair in some sort of logical order.
 
Thanks for the website. I'll start with the points and condensor, but first I'm going to reverse the coils, to rule them out.
 
Thanks for the advice Kim, but I'm pretty sure it's the condenser. It's for a sled, with external coils. I reversed the wiring going to the coils, so that what was No.1 is now No. 2 cyl. Still got fire on the same plug, so the coils are good. Points were cleaned and reset, only thing not worked on was the condenser. I re-soldered the lead to the one I think is bad, and got some spark from it. So, logic tells me I need a condenser.
 
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