Re: maybe i need to check it with a tach?

[David Stanton]

Those Merc/Yamaha connectors are metric and the hole is bigger, but like a couple of the other guys, I’m thinkin’ your prop your prop has too much pitch, but that may not be the whole problem. Those 14s are mainly for dual motor applications. I’m running 12-1/2 and 13 inch pitch on several OMC 35s I’ve had on my three 12′ and 14′ aluminum boats with good results. Changing one inch in pitch can be like putting a car in and out of overdrive. First thing I’d do with the carb is open it up and recheck the float level setting to be sure something didn’t get bent when the bowl was put on. The gas line, pickup line, connectors, etc, can all be problematic like the guys here said, but for an immediate bog on a turn, I doubt these items are the culprit if the boat was running strong when going straight. If gas line restrictions are marginally not keeping the carb quite full enough, it should run OK on corners if you run slightly less throttle, requiring less gas.
You mentioned you adjusted the carb high speed jet to the point where it was as lean as possible but not wanting to kill – You should be adjusting for max RPM, and you can hear this – it may need to be a tad richer than just above the edge where the motor starts to falter. I find the lean and rich settings where max RPM sounds like it’s dropping and set the knob half way between these points.
Dave