Swap carb's,
see if the problem follows to the other engine.

This is a relatively easy check.

jt

I had a simular problem on a vortech 350 It would make a loud pop intermitently sometimes like an automatic gun! but would go away and run great! I could not find the problem not in ignition or fuel so I ran it till it gave out. I was turnning about 4200 just as smooth as could be when I heard the fatal pop! On teardown their was nothing left of #5 piston The rod was twisted in two but crank was fine! It had to be a valve sticking! I took the hard way to go as I did not want to pull my heads but that's your choice! my engine had about 600 hours on it and was a 2000 model. good luck

If Its Only After Hitting A Wave, Ck The Connection Between The Engine And Harness (usually Hose Clamp To Secure It).
While Running Have Someone Give It A Twist Or Light Pull.
If It Stumbles, Realign Pins And Expand(slightly) And Secure

Checked Everthing,could Not Find Any Fuel Or Ignition Problem So I Did Comp Test,found Number 8 Cyclinder To Be Low,pulled The Head Last Night And Found A Burt Exhaust Valve.will Be Back On The Water Tomorrow!

Now you need to find out why you burnt it. Check your springs real good.

Mark