1995 Johnson 15hp no start

[tkers]

Hi, I have this 1995 15hp. It was on my parents' raft for years. It ran excellently. he gave it to me a few years ago. I never had issues until I broke the pull cord and it all went downhill from there. It did sit in my shed for two years. Now it won't start. I'll list all the things I have looked into. Carb kit, checked the fuel pump diaphragm, strong spark on both cylinders 7/16 on a tester, 90psi on top and 88 psi on the bottom, even pulled the flywheel and checked under there, the key is there. I'm not sure if the timing of the spark is adjustable. even with adding fuel directly into plugs, still doesn't even want to try and fire. Using a drill to turn over, my arm is getting sore. What should I look into next? Thanks
Edit

 

[racerone]

Switch plug wires ?

 

[tkers]

Yes I tried that as well. Would a plugged exhaust or something??

 

[tkers]

Switch plug wires ?

I tried tonight both spark plug wires on either plug. Still nothing, few times just a poof, that's it, not even sounding like a try to start .
Could spark timing be out?? If possible??

 

[bigtime_mcalpine]

does it attempt to start when you put a little fuel/oil mix right into cylinders?

 

[tkers]

does it attempt to start when you put a little fuel/oil mix right into cylinders?

Nope not at all

 

[racerone]

Weak spark or spark at the wrong time.

 

[tkers]

I tested and it jumps over 7/16 gap quite easily. Both plugs.
How do I adjust the spark timing? That's the only thing I can think of?