Re: 1995 Evinrude 8HP Yachttwin Two Stroke, Both Cylinders Firing?
Couple things you can do:
1 Remove the plugs to get rid of the compression; easier to pull. One at a time, ground each plug to the block and pull the starter. The plug should spark. Test each plug and respective lead.
2 Build a simple air gap tester as in the photo so you can test both plug leads at the same time. Spark should jump a 7/16" air gap. Again, pull the plugs to get rid of the compression; easier to pull. Attach the tester screws, one to each of the plug leads, ground the unit to the block. Pull the starter and you should see the sparks alternate one lead then the other.
Good luck!
J