1975 mercury 650 won't run in the water

[jakestevens]

I finally got a chance to put the 1975 mercury 650 2 stroke in the water last weekend. It wouldn't run enough to get it off the trailer. It would idle for a 10 seconds or so then choke out and die. I had replaced the trigger assembly and performed the timing and sync with the flusher (flaps), and it seemed to start and run ok, but when I put it in the water, it was like a different engine. Should I get a test tank and redo the timing and sync procedure?

 

[CharlieB]

Re: 1975 mercury 650 won't run in the water

More probable that your idle mixture is way wrong, adjust to best idle on the hose then open idle mixture screws another 1/4 turn out, readjust once on the water to best idle in gear plus 1/8 turn out, just enough that immediate WOT acceleration from idle in gear has no perceptible hesitation at all.