Rough Running and popping in neutral

[xandr55]

I have a 1973 Chrysler Autoelectric 9.9 model number 95HB. It has a few issues but one new one as of today, and I cannot seem to figure out where to start troubleshooting it. When in neutral it occasionally makes a kind of pop sound accompanied by a sudden drop in RPMs and then it takes a little gentle reving to get it back up. It does this multiple times, no matter what the throttle is at. At low RPMs the pop will actually stop the motor. At first i thought that it was a broken reed, however when i put the unit in forward gear I had no such issue, and did not notice any spewing out the front of the carb, which I have heard accompanies broken reeds. Any help would be great thank you.
Xander

 

[airframer]

Re: Rough Running and popping in neutral

how do the plugs look? sounds like your getting pre-ignition

 

[xandr55]

Re: Rough Running and popping in neutral

I haven't pulled them, my boat is parked about 1 mile from the library where I have internet access. Why though would I not be getting pre-ignition in forward gear? Also what would be the next step if my plugs are fouled? I have never adjusted timing before. Also I have the seloc manual but have not found it to be super helpful. Thanks,
Xander

 

[eurolarva]

Re: Rough Running and popping in neutral

Item 22 in the figure below is the fuel mixture screw. When motor is warmed up try turning this a 1/8 to 1/4 turn counter clockwise and see if it goes away. If it does try goosing the throttle and see if it go immediately or hesitates and then goes. I think you are running your carb too lean.

 

[xandr55]

Re: Rough Running and popping in neutral

This actually was the problem, I synchronized and tuned the carburetor and it has been running beautifully since, thank you so much.... I am very glad that it was that simple, at least this time.