Two 9.5s only run on top cylinder

[tt600]

I have two Johnson 9.5 and both will only run on the top cylinder. I checked compression and all four cylinders are the same. I swapped plugs, coils, set the points, etc. The plugs fire when I hold them to the frame and pull the cord. What am I missing?

 

[F_R]

Begin with a better spark test. It should jump a 1/4" sharp-pointed gap.

There are several other possibilities, but let's start with the simple stuff.

 

[tt600]

I tried swapping plugs and coils. I did not try swapping points or condensers. Would that make a difference? To me the spark looks the same in a dark garage. But how to tell?

 

[tt600]

I set the points at .02. If I set them farther or closer will it increase spark?

 

[RCO]

No reason to set the points at anything other than .020 . You most likely have bad condensers . If you have a meter that can read capacitance you can check them, otherwise just replace them they are cheap. Use a spark tester, should jump 1/4" open air gap .

 

[tt600]

Spark does seem to jump a 1/4” gap.

 

[F_R]

Well if you are sure you have 1/4" spark, time to look for something else. But I gotta tell you the "something else" on two different motors would be unusual.

Reeds??

Water getting into the cylinder?

 

[tt600]

I guess it was the plugs. Despite all four plugs making what appeared to me good spark I tried putting the top one in the bottom hole and got it to run. Which I swear I tried yesterday. So off to the hardware store for another new plug and now both cylinders are firing. I did switch the known good top condenser off the other motor to the bottom coil. Hard to believe that was it.
So I am ready for a lake test.
I tried all these plugs in a dark garage and all seemed to have the same quality of spark
I have never had this problem before. If I see good spark it will usually at least pop. Not totally dead.