Reply To: Backfire/misfire thru carb

[Don]

OK, so you have the “OMC Turbo jet”. First, I’m pretty sure that this unit has a fairly high idle speed to make sure it pumps enough water to cool the engine. And yes, it will be tough to look inside the carb throats to ensure both butterflies are closing fully.
So, like I said before, try moving the cam roller away from the cam slightly at idle speed..
Try disconnecting the link between the two butterflies, this should ensure both are closing fully provided the roller is not touching the cam….And yes, it is possible that one of the carbs has some sort of binding issue/wear causing its butterfly to stick open slightly, but this is not that likely.
Let me know if either of these steps clears up the idle, we can go from there with the syncronization….